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Schach, Rainer, and Manuel Hentschel. "Grundlagen für die Nutzwertanalyse für Verstärkungen aus textilbewehrtem Beton." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244049476991-75979.
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Im Rahmen des Transferprojektes sollen baubetriebliche Rahmenbedingungen und Kennwerte, die zur Beurteilung der wirtschaftlichen Anwendung des Verfahrens geeignet sind, erarbeitet werden. Untersucht werden soll die Applikation von textilbewehrtem Beton im Bereich der Sanierung und Verstärkung von großflächigen Betonbauteilen. Generell können Bauaufgaben in sehr vielen Fällen durch verschiedene Bauverfahren realisiert werden, die sich regelmäßig hinsichtlich der Kosten, der benötigten Bauzeit aber auch hinsichtlich der gelieferten Qualität und des Einflusses auf die Umwelt unterscheiden. Aus baubetrieblicher Sicht wird traditionell über den kalkulatorischen Verfahrensvergleich jenes Verfahren ermittelt, mit dem die Realisierung am wirtschaftlichsten ausgeführt werden kann. Falls qualitative Kriterien beim Verfahrensvergleich mit berücksichtigt werden sollen, stehen verschiedene Methoden zur Auswahl. Der Begriff Nutzwertanalyse wird häufig als Synonym für diese nichtmonetären Bewertungsverfahren verwendet. In diesem Sinne ist auch der Titel des Beitrages zu verstehen. Die Grundlage bilden die baubetrieblichen Rahmenbedingungen, welche im Rahmen dieses Forschungsprojektes bestimmt werden. Hierzu zählen unter anderem die Entwicklung einer Trockenmischung des zu verwendenden Betons aus der bisher verwendeten Standardrezeptur der TU Dresden und geeigneter Maschinen für die Applikation des textilbewehrten Betons.
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Vaccari, Elisa. "Meso mechanical analysis of asphalt concrete mixture response." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3299/.
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Vincent, Edward Creed. "Compressive Creep of a Lightweight, High Strength Concrete Mixture." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/30962.
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Concrete undergoes volumetric changes throughout its service life. These changes are a result of applied loads and shrinkage. Applied loads result in an instantaneous recoverable elastic deformation and a slow, time dependent, inelastic deformation called creep. Creep without moisture loss is referred to as basic creep and with moisture loss is referred to as drying creep. Shrinkage is the combination of autogeneous, drying, and carbonation shrinkage. The combination of creep, shrinkage, and elastic deformation is referred to as total strain.
The prestressed concrete beams in the Chickahominy River Bridge have been fabricated with a lightweight, high strength concrete mixture (LTHSC). Laboratory test specimens have been cast using the concrete materials and mixture proportions used in the fabrication of the bridge beams. Two standard cure and two match cure batches have been loaded for 329 and 251 days, respectively.
Prestress losses are generally calculated with the total strain predicted by the American Concrete Institute Committee 209 recommendations, ACI 209, or the European design code, CEB Model Code 90. Two additional models that have been proposed are the B3 model by Bazant and Baweja, and the GL2000 model proposed by Gardner and Lockman. The four models are analyzed to determine the most precise model for the LTHSC mixture. Only ACI 209 considered lightweight aggregates during model development. GL2000 considers aggregate stiffness in the model.
ACI 209 was the best predictor of total strain and individual time dependent deformations for the accelerated cure specimens. CEB Mode Code 90 was the best predictor of total strain for the standard cure specimens. The best overall predictor of time dependent deformations was the GL2000 model for the standard cure specimens.Master of Science
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Townsend, Bradley Donald. "Creep and Shrinkage of a High Strength Concrete Mixture." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/32743.
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In addition to immediate elastic deformations, concrete undergoes time-dependent deformations that must be considered in design. Creep is defined as the time-dependent deformation resulting from a sustained stress. Shrinkage deformation is the time-dependent strain that occurs in the absence of an applied load. The total strain of a concrete specimen is the sum of elastic, creep, and shrinkage strains.
Several test beams for the Pinnerâ s Point Bridge have been produced by Bayshore Concrete Products Corp., in Cape Charles, VA. These beams feature high strength concrete mix designs with specified 28-day compressive strengths of 55.2 MPa (8,000 psi) and 69.0 MPa (10,000 psi). These test beams were equipped with thermocouples to track interior concrete temperatures, and vibrating wire gages placed at the center of prestressing to record changes in strain.
Laboratory creep and shrinkage testing was conducted on specimens prepared with identical materials and similar mixture proportions to those used at Bayshore. The temperature profile from the test beams during steam curing was used to produce match-cured specimens for laboratory testing. Two match cure batches were produced, along with two standard cure batches. Creep specimens from each batch were placed in the creep room and loaded to 30 percent of their after-cure compressive strength. The creep room had a temperature of 23.0 ± 1.7 °C (73.4 ± 3 ºF) and relative humidity of 50 ± 4 %. Companion shrinkage specimens were also placed in the creep room. Measurements were taken on the creep and shrinkage specimens using a Whittemore gage. Four cylinders were also equipped with embedded vibrating wire gages (VWGs) so that the interior and exterior strains could be compared. The Whittemore and VWG elastic and creep strains were similar, while the VWGs recorded significantly less shrinkage.
The measured creep and shrinkage strains were compared to seven different models to determine which model was the most accurate. The models considered were ACI 209, ACI 209 modified by Huo, CEB Model Code 90, AASHTO-LRFD, Gardner GL2000, Tadros, and Bazant B3. The ACI 209 modified by Huo was most accurate in predicting time-dependent strains.Master of Science
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Edwards, Ylva. "Influence of waxes on bitumen and asphalt concrete mixture performance." Doctoral thesis, KTH, Väg- och banteknik, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-553.
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This doctoral thesis consists of a literature review, presented in two papers, and another six papers describing experimental studies of the influence of different kinds of wax and polyphosporic acid on bitumen and asphalt concrete mixture properties. The literature review should give an extensive description of the field of knowledge concerning wax in bitumen. Effects of wax in crude oil, bitumen and asphalt concrete as well as test methods for studying these effects are described. Theories behind possible mechanisms are also discussed, and commercial wax as additive to bitumen for different purposes included. The experimental parts comprise laboratory studies involving totally five 160/220 penetration base bitumens from different sources, two isolated bitumen waxes, five commercial waxes and one polyphosphoric acid. Asphalt concrete slabs, containing base or modified bitumen were prepared and tested. Binder properties were evaluated using different types of laboratory equipment, such as dynamic shear rheometer (DSR), bending beam rheometer (BBR), differential scanning calorimeter (DSC), force ductilometer, as well as equipment for determining conventional parameters like penetration, softening point, viscosity, and Fraass breaking point. Fourier Transform Infrared (FTIR) spectroscopy and Thin Layer Chromatography (TLC-FID) were used for chemical characterization. The binders were aged by means of the rolling thin film oven test (RTFOT) and pressure ageing vessel (PAV) in combination. Asphalt concrete properties were evaluated at low temperatures using the tensile strain restrained specimen test (TSRST) and creep test at -25°C. Dynamic creep testing was performed at 40°C, as well as complex modulus tests between 0 and 20°C. Binder test results indicated that the magnitude and type of effect on bitumen rheology depend on the bitumen itself, type of crystallizing fraction in the bitumen and/or type and amount of additive used. Bitumen composition was found to be of decisive importance. Adding polyethylene wax or polyphosphoric acid, especially to a non-waxy 160/220 penetration grade bitumen, showed no or positive effects on the rheological behaviour at low temperatures (decrease in stiffness) as well as medium and high temperatures (increase in complex modulus and decrease in phase angle). However, the corresponding positive effects could not be shown in dynamic creep testing (at 40°C) of asphalt concrete mixtures containing these modified binders. Adding FT-paraffin decreased the physical hardening index for all bitumens. Also polyethylene wax and montan wax showed this effect for some bitumens. Slack wax showed a large increasing effect on physical hardening, and polyphosphoric acid none or a minor negative effect. No correlation between physical hardening index (PHI) and wax content by DSC was found in this study, involving both natural bitumen wax and commercial wax. Addition of the commercial waxes used showed no or marginally positive influence on bitumen ageing properties for the bitumens and test conditions used. Comparing asphalt mixture test results to the corresponding binder test results, the effects on asphalt mixtures from adding commercial wax or polyphosphoric acid were less evident. Significant binder physical hardening by BBR could not be confirmed by TSRST.QC 20101006
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Tekin, Ahmet Veli. "Effect Of Coating Materials And Mixture Constituents On The Permeability Of Concrete." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614214/index.pdf.
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The improvement in the impermeability of concrete was studied using different methods. The main aim was to investigate impermeability improvement of concrete and to compare these methods. Two different methods were examined to investigate and compare impermeability and strength improvement of concrete by using two different sets of concrete specimens. These methods included the application of coating materials to concrete and the production of concrete using different constituent amounts and types. The first set of concrete specimens was prepared by applying two different coating materials (a coating material including both powder and liquid componentsand a coating material including only a liquid component) on reference concrete specimens separately. The second set of concrete specimens was prepared using different proportions of concrete constituents such as cement, water, steel and plastic fibers, mineral and chemical concrete admixtures. Various tests were conducted on both sets of concrete specimens in order to compare the permeability of concrete specimens. However, some of these tests v were not applied on all of the specimens because of test and material specifications. The tests were used to evaluate compressive strength, water absorption, chloride ion penetration and depth of water penetration under pressure. These test methods were carried out on concrete cube specimens and concrete cores taken from those specimens according to the relevant standards. It was found that the permeability of the concrete specimens decreased significantly when the coating material which was composed of the combination of powder and liquid components was applied on concrete specimens. However, permeability did not decrease significantly for concrete specimens coated with the coating material composed of only a liquid component. Significant improvement in the impermeability of the concrete specimens was observed when the amount of cement was increased, the water-to-cement ratio was decreased, mineral admixtures (silica fume and fly ash) and plasticizers were used. This improvement was associated with densification of the concrete microstructure and reduction in capillary pores as a result of pozzolanic reaction and due to reduction in water-to-cement ratio. Coating materials were determined to be effective for concretes with high permeability prior to coating whereas their effect was less significant for lower-initial permeability concretes. Moreover, the effect of coating materials on permeability differed depending on their chemical compositions. The effect of using steel fibers and plastic fibers for the improvement of concrete impermeability was found to be insignificant.
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Rostami, Vahid. "Development of early carbonation curing to replace steam curing for precast dry-mix concrete." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114470.
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Early carbonation curing technology was developed to replace steam curing for precast dry-mix concrete production. To facilitate carbon dioxide diffusion in concrete within 24-h after casting, presetting is necessary. It was accomplished by a short steam curing or by a controlled air curing. Carbonation was carried out after presetting at a gas pressure of 0.15 MPa and in a period of two hours. The performance of carbonated concretes was characterized by their carbon uptake, strength gain, pH values, calcium hydroxide content, permeability, sorptivity, freeze-thaw damage resistance and sulphate and acid resistance. It was found that the early carbonation curing could produce concrete with comparable strength by steam curing and lead to reduced calcium hydroxide on surface while maintaining pH higher than the corrosion threshold at the core. Carbonated concretes also exhibited improved resistance to sulphate attack, water absorption, and ion penetration. The early carbonation curing also demonstrated CO2 sequestration potential as an added value to the process. The microstructure of the cement paste subject to early carbonation was studied to understand the mechanism of early carbonation of concrete. Calcium carbonates produced by the process were integrated in calcium-silicate-hydrate while maintaining its initial silicate structure. The wetting procedure applied in subsequent hydration was essential to produce more hydration products in the carbonated zone and increase strength and durability. Both ordinary Portland cement (OPC) and Portland limestone cement (PLC) were investigated for their carbonation behaviour. PLC was found to be more CO2 reactive.La technologie de cure par carbonatation précoce a été développée pour remplacer la cure par étuvage pour la production du béton mélange-à-sec préfabriqué. Afin de faciliter la diffusion du dioxyde de carbone dans le béton dans les 24 heures après le moulage, le préréglage est nécessaire. Ceci a été accompli par une cure par étuvage de courte durée ou par une cure par air contrôlé. Après le préréglage, la carbonatation a été effectuée à une pression de gaz de 0,15 MPa et dans une période de deux heures. La performance des bétons carbonatés a été caractérisée par leur absorption de carbone, le gain de résistance, les valeurs de pH, la teneur en hydroxyde de calcium, la perméabilité, la sorptivité, la résistance au gel-dégel ainsi qu'aux sulfates et à l'acide. Il a été constaté que la cure par carbonatation précoce pourrait produire du béton avec une résistance comparable à la cure par étuvage. Aussi, il a été noté que la carbonatation précoce pourrait résulter à une réduction de l'hydroxyde de calcium sur la surface tout en permettant le pH au coeur d'être supérieure à la valeur seuil de la corrosion. Des bétons carbonatés ont également présenté une résistance améliorée aux attaques des sulfates, à l'absorption de l'eau et à la pénétration des ions. En plus, la cure par carbonatation précoce a démontré le potentiel de séquestration du CO2 comme une valeur ajoutée au processus.La microstructure de la pâte de ciment soumise à la carbonatation précoce a été étudiée afin comprendre le mécanisme de carbonatation du béton. L'hydrate silicate de calcium (HSC) dans le ciment carbonaté était fortement intégré avec les carbonates de calcium tout en conservant sa structure silicatée initiale. La procédure de mouillage appliquée à l'hydratation ultérieure a été essentielle afin de produire plus de produits d'hydratation dans la zone carbonatée et d'augmenter la résistance et la durabilité. Le ciment Portland ordinaire (CPO) et le ciment Portland au calcaire (CPC) ont été étudiés pour comprendre leur comportement lors de la carbonatation. Le CPC est en mesure d'absorber plus de dioxyde de carbone et de produire une résistance plus élevée à un âge précoce.
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Bennie, Stewart David. "Development of a performance based, integrated design/selection mixture methodology for fiber reinforced concrete airfield pavements." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1464.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2004.Thesis research directed by: Civil Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Jung, Sung Hoon. "The effects of asphalt binder oxidation on hot mix asphalt concrete mixture rheology and fatigue performance." [College Station, Tex. : Texas A&M University, 2006. http://hdl.handle.net/1969.1/ETD-TAMU-1754.
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Beck, Lisa Elanna. "Diffusivity and resistance to deterioration from freezing and thawing of binary and ternary concrete mixture blends." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/8784.
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Master of ScienceDepartment of Civil Engineering
Kyle Riding
Corrosion of reinforcing steel is one of the most common and serious causes of reinforced concrete deterioration. While corrosion is normally inhibited by a passive layer that develops around the reinforcing steel due to the high pH environment of the surrounding concrete, chlorides will break down this protective layer, leading to reinforcement corrosion. Decreasing the diffusivity of the concrete would slow the ingress of chlorides into concrete, and is one of the most economical ways to increase the concrete service life. Optimized concrete mixtures blending portland cement and supplementary cementing materials (SCMs) have become popular throughout the construction industry as a method of improving both fresh and long-term concrete properties such as workability, strength and porosity. It has been shown that use of Class F fly ash, silica fume and ground granulated blast furnace slag (GGBFS) in binary concrete mixture blends can result in a significant reduction in concrete diffusivity. This study investigates the ability of Class C fly ash and ternary concrete mixture blends to also aid in diffusivity reduction. In order to study the effect of incorporation of SCMs into concrete, mixtures containing Class C and Class F fly ash, silica fume and GGBFS were tested following the ASTM C 1556 procedures to measure the concrete’s apparent chloride diffusivity. Structure life cycles were modeled using the measured apparent chloride diffusivities with two finite-difference based life-cycle analysis software packages. To determine whether a correlation between diffusivity and deterioration due to freezing and thawing exists, samples were also tested for their ability to resist deterioration from freezing and thawing cycles using a modified ASTM C 666 Procedure B test. Results show that the use of Class C fly ash yields some service life improvements as compared to the portland cement control mixtures, while ternary mixture blends performed significantly better than the control mixture and equal to or better than the binary SCM mixtures tested. Freeze-thaw tests showed all mixtures to be equally resistant to deterioration due to freezing and thawing.
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Hailesilassie, Biruk. "Morphology Characterization of Foam Bitumen and Modeling for Low Temperature Asphalt Concrete." Doctoral thesis, KTH, Byggnadsmaterial, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-183105.
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Development of new asphalt technologies to reduce both energy consumption and CO2 production has attracted great interest in recent years. The use of foam bitumen, as one of them, is attractive due to the low investment and production cost. Formation and decay of foam bitumen is a highly dynamic temperature dependent process which makes characterization difficult. In this thesis, new experimental tools were developed and applied for characterizing the foam bitumen during the hot foaming process. One of the main goals of this study was to improve understanding and characterization of the foam bitumen formation and decay. X-ray radiography was used to study the formation and decay of foam bitumen in 2D representation. The results demonstrate that the morphology of bubble formation depends on the types of bitumen used. Moreover, theoretical investigation based on the 3D X-ray computed tomography scan dataset of bubble merging showed that the disjoining pressure increased as the gap between the bubbles in the surface layer (foam film) decreased with time and finally was ruptured. Examining the foam bitumen stream right at the nozzle revealed that foam bitumen at a very early stage contains fragmented pieces of irregular size rather resembling a liquid than foam. The result from thermogravimetric analysis demonstrated that residual water content depends on the initial water content, and was found to be between 38 wt% and 48 wt% of the initial water content of 4 wt% to 6 wt%. Moreover the influence of viscosity and surface tension on bubble shape and rise velocity of the bubbles using level-set method was implemented in finite element method. The modeling results were compared with bubble shape correlation map from literature. The results indicated that the bubble shapes are more dependent on the surface tension parameters than to the viscosity of the bitumen, whereas the bitumen viscosity is dominant for bubble rising velocity.QC 20160303
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Eixenberger, Joseph G. "Seismic Analysis of and Provisions for Dry-Stack Concrete Masonry Wall Systems with Surface Bond in Low-Rise Buildings." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6547.
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Masonry is one of the oldest forms of construction materials that is still in use today. However, construction practices in the modern age demand faster and more economical practices. Dry-stack masonry, or masonry that doesn't use mortar to bind the blocks together, is a unique system to make masonry more economical. Though several systems of dry-stack masonry have been suggested little to no data exists as most of these systems are patented. This research used dry-stacked normal weight concrete masonry units with an eccentrically placed reinforcement. The wall system is connected through a surface bond and lacks any geometric connection. Previously, research has been conducted on the wall system for its axial compressive capacity, but little information is known about its ability to withstand lateral forces such as earthquakes. Research was conducted on the wall system in order to determine the seismic parameters, including the force reduction factor, overstrength factor, and the displacement amplification factor. To determine these factors the guidelines from the Federal Emergency Management Agency (FEMA) Quantification of Building Seismic Performance Factors 2009 were followed. The guidelines are explicit that both experimental data and computer modeling are needed to quantify these parameters. Experimental data was obtained from a diagonal tension test, and an in-plane shear test. The diagonal tensions test provided preliminary values on the shear modulus and shear resistance. The in-plane shear test was of primary interest and what would be used to verify the computer model. Computer modeling of the wall system was accomplished with Vector 2. Initially the computer modeling was done to reproduce experimental data. Then, a parametric study was performed using the model to see what component of the wall most effected its capacity. This analysis showed that the surface bond was the component of the wall that most affects its capacity. Finally, the computer model was run through the FEMA Far-Field earthquake suite to gather data on the strength and ductility. Values of the force reduction factor, overstrength factor, and displacement amplification factor were determined based on the time history analysis and pushover analysis on the computer model.
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Abdul, Le Brun Laure. "Mise au point d’une méthodologie pour la formulation des bétons secs à démoulage immédiat." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS035/document.
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De nos jours, le bloc est le produit le plus vendu en préfabrication, avec un chiffre d’affaires de 418 millions d’euros en 2015 (chiffres issus de la Fédération de l’Industrie du Béton). Toutefois, ce résultat atteste d’une baisse de production constatée depuis 2012.Dans ce contexte économique difficile, les industriels cherchent à optimiser la formulation de leurs produits. Les particularités de ceux-ci (consistance sèche et teneur en air moyenne comprise entre 7 et 15 %) rendent impossible l’utilisation des outils existants.L’objectif de la thèse est alors de mettre au point une méthode de formulation adaptée aux blocs, permettant d’optimiser le rapport coûts/performances. Cela implique de diminuer le dosage en ciment, matériau le plus couteux du béton et également le plus négatif en termes d’émissions de CO2. Pour cela un squelette granulaire optimal doit être utilisé.La méthodologie de formulation mise au point se déroule ainsi en deux étapes. La première consiste à sélectionner le mélange granulaire présentant l’arrangement maximal. La deuxième détermine les volumes des autres constituants (ciment, eau efficace, air et addition) en fonction des exigences de consistance et de performances mécaniques. Les travaux ont permis d’obtenir un modèle d’empilement compressible adapté à la mise en place des mélanges granulaires secs à l’aide d’une presse vibrante et d’un moule de bloc. Celui-ci calcule la compacité des mélanges granulaires dans de telles conditions et permet de sélectionner le mélange optimal. Les travaux ont également permis de relier les propriétés aux états frais et durcis à la formulation des bétons secs. La résolution du système d’équations obtenu permet de déterminer la formulation qui optimise le rapport coûts/performances.Un outil numérique regroupant ces résultats est développé. Il nécessite de renseigner un ensemble de données (squelettes granulaires, masses volumiques réelles, coûts, etc.), ainsi que les exigences de consistance et de performances mécaniques. Il propose alors la formulation optimisant le rapport coûts/performances. Celle-ci peut ensuite être testée à échelle réduite sur des cubes car les résultats ont permis de relier les performances mécaniques des cubes et des blocsConstruction’s sector is knowing an important mutation and is confronted with unpresented stakes with major importance for next decades: population growth and needs in accommodation and infrastructures, climate change, uses of durable and natural resources, societal expectations from consumers as well as territorial’s stakeholders. Concrete precast industry is strongly enlisted to answer at these news needs, for the constructive systems proposed as well as for the production processes of concrete’s products. The stake is especially important for concrete masonry units with a production in France in 2017 of 6.7 million tons. These products are realized using press which compact concrete with vibration and pression. Blocs are made of dry cast concrete with average air content between 7 and 15%. Today, formulation methodologies are adapted to delayed demoulding products and so not made for bloc concrete.This thesis aims to develop a formulation methodology adapted to blocs and to their process, in order to optimize their performances in economic conditions. This implies disposing of robust tools able to determine optimal proportions for each constituent, considering process specifications. Especially, it is necessary to use an optimized aggregates mix.The formulation methodology developed runs through two steps. The first one consists in choosing the aggregates mix with maximal packing density. The second one determines other constituents volumes (cement, efficient water, air and addition) according to consistency and mechanical performances requirements. The compressive packing model (F.de Larrard) is adapted to dry aggregates mix casting with vibrating press in a bloc mold. Results also make it possible to connect fresh and hardened properties to the formulation of dry cast concretes. Solving the system of equations gives the formulation optimizing the ratio costs/performances
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Felipe, Alexsandro dos Santos. "Contribuição para a otimização de traços de concreto utilizados na produção de blocos estruturais /." Ilha Solteira : [s.n.], 2010. http://hdl.handle.net/11449/91466.
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Resumo: Diante do grande crescimento da alvenaria estrutural no país, muitas fábricas de blocos de concreto vieram por necessidade, buscar por otimizações do seu processo produtivo, visto que, projetos mais arrojados, acabam exigindo maiores controles de qualidade. A proposta deste estudo é melhorar a produção destes artefatos de concreto por meio de otimizações simples que reduzem o custo e garantem uma produção eficiente na fábrica. Estudar a fundo os vários parâmetros de formação de um traço de concreto seco, tais como coesão, textura, energias de adensamento e resistência à compressão axial, todos os fenômenos dependentes entre si, torna-se muito complexo se avaliado em um único trabalho. No entanto, propor um estudo que colete informações apresentadas por vários autores, facilita na otimização e criação de uma pesquisa que possa contribuir na dosagem para concretos secos, em especial, na fabricação de blocos estruturais. Neste estudo, adaptaram-se para laboratório alguns equipamentos de uso comum para confecção destes artefatos de concreto, possibilitando a correlação direta de corpos de prova cilíndricos com os blocos. Uma das adaptações é o estudo baseado na padronização da energia de compactação, proporcionada pelo equipamento para ensaios de mini-proctor, simulando assim, a máquina vibro-prensa. Outras correlações como coesão e resistência à compressão, também foram possíveis de obter no laboratório, reduzindo então, as interferências constantes no processo produtivo da fábrica, ocasião verificada em vários outros estudos. Diante do exposto, foi possível avaliar com boa segurança os resultados. O estudo foi desenvolvido em três etapas, sempre buscando a maior massa específica seca compactada da mistura de agregados, inicialmente na primeira etapa, foi utilizado somente dois agregados (areia fina e pedrisco), conforme... (Resumo completo, clicar acesso eletrônico abaixo)Abstract: Given the substantial growth of structural masonry in Brazil, many concrete block companies have seen the need to optimize their production process, since more challenging projects require greater quality control. This study proposes to improve the production of concrete artifacts by means of simple optimizations that reduce costs and ensure the company's efficient production. Studying in depth the various parameters of the formation of dry concrete trace, such as cohesion, texture, density energy and axial compressive strength, all the particularities interdependent on one another become very complex when assessed in a single study. However, proposing a study that collects the information submitted by various authors, expedites optimizing and creating a research study which may assist in improving the dosage for dried concrete, particularly in the manufacture of structural blocks. In this study, some commonly used manufacturing equipment, such as concrete artifacts, were laboratory-adapted, enabling a direct correlation of the cylindrical specimens with the blocks. One of the adjustments is the study based on the standardization of compaction energy, provided by the mini-proctor testing equipment, thus simulating the vibro press machine. Other correlations such as cohesion and compressive strength were also obtained in the laboratory, therefore reducing the constant interferences in the plant's production process, observed in many other studies. In this manner, it was possible to reliably assess the results. The study was conducted in three stages, always seeking the highest compressed dry specific mass of the mixture of aggregates. In the first stage, only two aggregates were used (fine sand and pebbles), commonly used at the plant. The second stage included adding the coarse sand and stone powder to correct the lack of resistance promoted by the high amount of fine sand from... (Complete abstract click electronic access below)
Orientador: Jefferson Sidney Camacho
Coorientador: Maria da Consolação F. de Albuquerque
Banca: Jorge Luís Akasaki
Banca: Paulo César Primo Agostinho
Mestre
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Lintz, Rosa Cristina Cecche. "Dosagem de concreto de elevado desempenho pelo processo da calda de cimento." Universidade de São Paulo, 1997. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-16122010-100814/.
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Nesta dissertação são apresentados um método de dosagem de concreto de elevado desempenho baseado na reologia da calda de cimento e os resultados de sua aplicação para alguns materiais brasileiros. O método baseia-se em dois modelos teóricos: modelo reológico que trata da viscosidade de uma suspensão de grãos polidispersados e fórmula empírica para previsão da resistência do concreto considerando a resistência da argamassa padrão. O método apresenta como vantagens a economia em mão de obra e materiais, uma vez que manipula somente caldas de cimento. Por outro lado, permite chegar a misturas de concreto auto-adensáveis quando frescos e de alta resistência quando endurecida. A aplicação do método aos materiais brasileiros é feita com algumas modificações em relação ao método original: corpos de prova de formato cúbico, cura térmica do concreto em água em ebulição, emprego de cimento Portland comum, etc. As principais conclusões resultantes desta aplicação são: precisão da fórmula de previsão da resistência do concreto, fixação do teor ótimo de superplastificante e de adição mineral, confirmação do teor ótimo de sílica ativa nos CEDs, eficácia da cura térmica em água em ebulição, eficiência do emprego de corpos de prova cúbico e diferente comportamento dos diversos materiais empregados.In this dissertation are presented a mix method for high performance concrete base don rheology of cements pastes and on results of its application to some brazilian materials. The method is based on two theoretical models: a rheological model dealing with the viscosity of a polydispersed suspension and a empirical formula that allows the prediction of compressive strenght of standard mortar. The method presents as advantage the economy of manual work and materials since just handles binding pastes. Otherwise it allows to obtain self¬-densified mistures when concrete is fresh strength when concrete is hardened. The method application to Brazilian materials is done with some changes in relation to its originality: cubic specimen, thermal curing of concrete in boiling water, use of commom Portland cement, etc. The main conclusions drawn after this application are: accuracy of the prediction of concrete strength by the extended formula, determination of the best percentage of mineral and chemical addition, ratification of the best percentage of condensed silica fume in high performance concrete mixtures, effectiveness of the thermal curing of concrete en boiling water, effectiveness in the use of cubic casting mould and different behavior for several materials applied in this research.
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NASCIMENTO, Maria Victória Leal de Almeida. "Estudo de blocos intertravados de concreto para pavimentação de resíduo do polimento do porcelanato." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/17151.
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A utilização de resíduos em materiais cimentícios, tem sido desenvolvida para melhorar a qualidade ambiental, diminuindo os resíduos gerados. O RPP é um resíduo industrial produzido em grande escala pela indústria cerâmica, ele foi utilizado nesse trabalho sendo incorporado em blocos intertravados de concreto. Os blocos intertravados de concreto foram escolhidos dentre os materiais cimentícios, por não ter sua trabalhabilidade comprometida, quando se trata de adicionar um material pulverulento, pois é produzido por vibro-compressão. Foi realizada a otimização do empacotamento dos agregados, para a produção dos blocos intertravados de concreto, através de método matemático. Também foi otimizada, através de método experimental a relação água/cimento. O traço de referência, encontrado após as otimizações, foi 1: 2,68: 2,32 (cimento: areia: pedrisco), com relação água/cimento de 0,45, atendeu as especificações da NBR 9781 (ABNT, 2013), com relação a resistência à compressão. A partir do traço de referência foi realizado o empacotamento matemático para a incorporação do RPP. O resíduo foi considerado como agregado no empacotamento, ele foi incorporado nas seguintes porcentagens: 3% de RPP, 6% de RPP, 9% de RPP, e 12% de RPP, afim de avaliar a influência do resíduo nos blocos intertravados de concreto, nas propriedades do estado endurecido. A presença do RPP, reduziu a absorção de água tendendo a trazer para o admitido pela NBR 9781 (ABNT, 2013), manteve a resistência a abrasão de acordo com as especificações da NBR 9781 (ABNT, 2013), embora tenha prejudicado a resistência a compressão, sendo promissor a sua utilização, em blocos intertravados de concreto, em situações onde não há tráfego de veículos, como em: passeios públicos, praças, parques infantis, áreas que necessitem de drenagem. O traço com a incorporação do resíduo, que de uma forma geral obteve os resultados mais satisfatórios foi o traço 2 (3% RPP), que apesar da resistência à compressão média ter sido de 14,26 MPa menor que o especificado pela norma, apresentou uma taxa de absorção média de 6,60%, e em relação a resistência à abrasão apresentou uma cavidade média de 17,50 mm.
To incorporate residues in cimentitious materials has been developed to improve the environmental quality, reducing the amount of disposed residues. The ceramic porcelain industry generates a large amount of porcelain tile polishing residue. This work proposes to incorporate this tile polishing residue in concrete interlocking blocks. The concrete interlocking blocks were chosen due to the addition of a powder material not prejudice their workability, once they are molded by vibrocompression. It was determined the best packaging by a mathematical method. The water-cement ratio was also optimized by the experimental method. The achieved reference mix proportion after all optimizations was 1:2.68:2.32 (cement: sand: gravel) with ratio water-cement ratio 0.45. The compressive strength of the reference mix proportion is according to the NBR 9781 (ABNT, 2013). In the sequence, based on this reference mix, the incorporation of the residue was also mathematically optimized. The residue was considered as an aggregate on the packaging method. The residue was incorporated at the following percentages: 3%, 6%, 9% and 12% in order to evaluate its influence on the hardened state properties of the concrete interlocking blocks. The presence of the tile polishing residue reduces the water absorption, tending to bring the values to the admitted one by the NBR 9781. The abrasion resistance was in agreement with the NBR 9781 (ABNT, 2013). However, the compressive resistance was reduced, limiting the applications of the concrete interlocking blocks with the addition of tile polishing residue where there is no vehicle traffic, as in public footpaths, parks, playgrounds or areas requiring drainage. In a general way, the most satisfactory result among the evaluated mixes incorporating tile polishing residue was to the mix 2 (3% of residue). Despite the average compressive strength was 14.26 MPa lower than the specified by the standard, this mix presented the average absorption of 6.60% and 17.50 mm as a medium cavity liner in the abrasion resistance test.
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Marchioni, Mariana Lobo. "Desenvolvimento de técnicas para caracterização de concreto seco utilizado na fabricação de peças de concreto para pavimentação intertravada." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-18072013-150832/.
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O concreto seco, também chamado de concreto sem abatimento (no-slump) é utilizado na produção de artefatos de cimento, como por exemplo em peças de concreto para pavimentação, blocos para alvenaria e tubos de concreto e ainda como camada de subbase de pavimentos com a técnica de concreto compactado a rolo. A técnica de conformar concretos com reduzido teor de umidade através de equipamentos que aplicam simultaneamente compressão e vibração é amplamente utilizada na produção de artefatos de concreto, como as peças de concreto para pavimentação intertravada. Para as peças de concreto o desafio é ainda maior, pois as especificações de resistência característica à compressão podem chegar a 50 MPa. A principal característica do concreto seco é o baixo teor de água e elevada coesão, necessitando de energia de compactação e vibração para a eliminação de vazios e o concreto assumir a forma desejada. Esta técnica permite a desfôrma imediata, que garante elevada produtividade e consequente diminuição dos custos de produção. Já a compactação permite obter componentes de concreto com menor consumo de cimento se comparados ao concreto plástico. Diferentemente de toda literatura e metodologias de dosagem encontradas para o concreto plástico, o concreto seco encontra barreiras técnicas para a aplicação de metodologias que otimizem sua dosagem, em formulações empíricas que não levam em conta de forma adequada as características dos agregados, características estas diretamente ligadas à compacidade das peças, que por sua vez tem grande influência nas características do produto final. Além disto, há poucos estudos do comportamento reológico do concreto seco, que influenciam a fluidez e coesão da do concreto e que irão determinar a produtividade e qualidade da produção. Dessa forma, neste trabalho é apresentado uma metodologia para caracterização do concreto seco nos estados fresco e endurecido que permite o desenvolvimento sistemático de formulações com maior facilidade de compactação e que também resulte na melhoria do desempenho das peças e diminuindo a necessidade de testes em escala real. O método se baseia em produzir em laboratório um corpo de prova que reproduz as condições de moldagem de uma vibroprensa, eliminando-se a variável da vibração e padronizando as condições de compressão. Nos corpos-de-prova são avaliadas características nos estados fresco e endurecido, além de aspectos do comportamento reológico do concreto, através de técnicas de reologia compressiva. Para aferir a metodologia foram utilizadas amostras de referência produzidas em uma fábrica de peças de concreto. Com a metodologia proposta, foi possível atingir 90% da resistência mecânica das peças produzidas em uma vibroprensa de alta compactação. Sendo assim esta metodologia poderá ser utilizada em estudos de dosagem de concreto seco, portanto o trabalho desenvolvido é indicado na utilização de dosagens de concreto seco, obtendo-se maior ecoeficiência, a medida que otimiza o consumo de cimento da mistura e facilita o estudo de dosagem de materiais alternativos em substituição aos agregados convencionais.The dry concrete, also known as earth moist concrete or no-slump concrete, is most used to manufacture precast concrete products, as paving blocks, masonry blocks and concrete tubes, and also in rolled compacted concrete pavement. Its most important property is the low water content, and it requires mechanical equipment for its compactation. Paving blocks are normally manufactured using vibrocompression equipment, which at the same time applies both compaction and vibration resulting in paving blocks with high durability and mechanical resistance. Even though this technique is highly used it still lacks studies on some important steps of the manufacturing process. The mix design techniques are mostly empirical and dont deeply consider the aggregate characteristics, that are connected with its compacity and, by that, the characteristics of the paving block. Also, there are only a few studies of the rheology characteristics of dry concrete, which relates with de manufacturing process and the easiness that the mix is compacted. So, the object of this study is to develop a dry concrete characterization methodology that allows the systematic development of mix designs that are easily compacted and also improves the performance of the paving blocks.
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Palnati, Mahendra. "Design, Fabrication and Analysis of a Paver Machine Push Bar Mechanism." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/6007.
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Now-a-days, the major challenge that’s being faced by the concrete industry is the cleaning of concrete handling equipment. Concrete consists of aggregates, which harden with time, and the transportation of concrete mixture within the plant is a significant problem. This will not only increase the overall maintenance cost, but will lead to loss of raw materials, affect the rate of production, and reduce the lifetime of concrete handling equipment.
The present study focuses on the design and implementation of an adaptive cleaning mechanism in the concrete industry and its importance in achieving efficient cleaning, which is tested to verify its performance in the Paver production plant. The goal of this study is to provide practical evidence about the importance of adaptive cleaning mechanisms for industrial applications.
The first chapter gives a detailed introduction about pavers and the production process, the cause of material loss that occurs during transportation of wet concrete mixture inside a paver plant, and its effect on handling equipment and work environment. The second chapter explains design and working of the paver machine push bar mechanism, which can be implemented in a hydraulic press production process of pavers. The third chapter includes analysis and results of the mechanism obtained using Solidworks and Autodesk Inventor followed by observations that are achieved based on practical application of this mechanism in a paver production plant.
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Kurimai, Igor. "Řízení mísírny betonových směsí." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217771.
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Thesis presents control of concrete mixcure technology Prefa Brno – production plant Strážnice. It deals with areas of process control system using the control system Siemens S7 – 300. The first part of thesis describes concrete mixcure technology and control system SIMATIC S7 – 300. Algorithms, used for control of concrete mixcure technology, are designed in the next part of thesis. Further it is discussed control program and connection to the system SCADA. Time frame of process is described in the finally. There are defined critical processes, which can occur in the control. In the next the thesis deals with hardware performance for different types of concrete mixcure technology. The results of introduction control system into industrial process are analysed at the end.
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Persson, Herman, and Alexandru Zamfir. "Uttorkning av betong i nyproduktion." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-97204.
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Under de senaste åren har tillverkningsprocessen av betong genomgått en förändring föratt göra materialet och processer mer miljövänliga. Detta är en följd av att betong räknasvara ett av de viktigaste byggnadsmaterialen i världen. En viktig anledning till denomfattande användningen av betong är att betong som material är fuktbeständigt, att detinte möglar och att det är väldigt formbart.Förenta nationerna nämner 17 globala mål vars uppgift är att främja hållbarhet i framtidendär mål nio anger ”Bygga upp en motståndskraftig infrastruktur, verka för eninkluderande och hållbar industrialisering och främja innovation”. Detta faktum måstenaturligtvis tas hänsyn till även vid tillverkningen av betong och dess beståndsdelar.Syftet med det här examensarbetet är att med hjälp av ett stort antal mätpunkter visa påolika styrkor och svagheter inom tre olika typer av prognostiserande beräkningsverktygav torkningstider. Målet med arbetet är att jämföra statistik av praktiska mätningar,utfärdade av Conservator AB, med varandra och med de tre vanligasteberäkningsprogrammen som används för att beräkna uttorkningstider av betong.I de undersökta byggdelarna i arbetet gav TorkaS den högsta noggrannheten och sedanföljt väldigt nära av PPB. Utöver detta uppfyller de förväntningar som borde kunna ställaspå prognostisering av uttorkningstid för betong. Studien har också visat attuttorkningstiden för betong i nyproduktion påverkas mest av uttorkningsklimatet och tjockleken på avjämningsmassan.In the recent years, the manufacturing of concrete has undergone a change to make theprocesses and the material more environmentally friendly. This is accompanied by thefact that concrete is one of the most important building materials in the world. This islargely because concrete as a material is moisture resistant, does not mold and is highlyformable.The United Nations mentions 17 global goals whose mission is to promote sustainabilityin the future whereas the ninth one states that “Build resilient infrastructure, promoteinclusive and sustainable industrialization and foster innovation”. This leads to the factthat it needs to take in consideration the manufacturing of concrete and its components.The purpose of this research is to show strengths and weaknesses in prediction tools forconcretes drying time by comparison with data from many measuring points. Besidesthat, the aim is to compare statistics of practical measurements, which were issued byConservator AB, with each other and with other three most commonly used programs inforecasting the drying time for concrete, i.e. TorkaS, BI-Dry and PPB.From the building sections that were researched, TorkaS gave the highest accuracy inforecasting the drying time and then followed very closely by PPB. In addition, BI-Drydid not meet the expected requirements on some of the building sections. Besides that, thestudy has shown that the drying time of concrete in new production is most influenced bythe drying climate and the thickness of the compound.
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Sarfin, Md Abdullah Al. "Parametric Study of Mixture Component Contributions to Compressive Strength and Impact Energy Absorption Capacity of a High Strength Cementitious Mix with no Coarse Aggregate." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7601.
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This research project has been undertaken to produce and characterize the behavior of High Strength Cementitious Mix (HSCM), which has considerably higher compressive strength compared to conventional concrete. Components of HSCM are cement, silica fume, sand, water, and high range water reducer. The material is tested for compressive strength and impact energy absorption capacity while the amount of above mentioned components are varied parametrically. The effect of these parameters are extensively studied and trends are reported. Finally, this research projects attempts to find correlations among compressive strength, compressive toughness, and impact toughness. Limitations of the experimental program are discussed and future direction for improvement and expansion of the research program is suggested.
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ALCANTARA, Paloma Santos Xavier de. "Blocos intertravados coloridos para pavimentação com incorporação de resíduos de cerâmica vermelha em prol da redução de pigmentos." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/16647.
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CAPES
Peças de concreto intertravadas para pavimentação (pavers) coloridas com pigmento de óxido de ferro (vermelho) são utilizadas em projetos de urbanização. Entretanto, esse tipo de pigmento, além de encarecer de 20 a 30% o valor das peças, prejudica as propriedades dos concretos secos moldados sob vibrocompressão. Diante disso, propõe-se incorporar resíduo de cerâmica vermelha (RCV) como matiz colorimétrica em prol da redução de pigmento em pavers coloridos, tendo em vista também a possibilidade de melhoria de suas propriedades por efeitos filler e pozolânico. A fim de investigar o efeito do pigmento e do RCV no compósito estudado, as formulações foram: (a) traço padrão pelo método de dosagem da ABCP para blocos e pavers; (b) adição de pigmento ao traço padrão (2% e 4%); (c) substituição da areia média pelo RCV no traço padrão (50%, 75% e 100%); (d) adição de RCV ao traço padrão (20%, 30%, 40% e 50%); (e) adição de pigmento (2%) e RCV concomitantemente ao traço padrão (20%, 30%, 40%, 50%, 100% e 150%). Para todos os traços (exceto aqueles das formulações de substituição), foi feita a correção do consumo de cimento em relação ao traço padrão. Resistência à compressão, absorção de água e resistência à abrasão foram avaliadas de acordo com a norma NBR 9781:2013; além disso, foi realizada uma avaliação das cores dos compósitos desenvolvidos por inspeção visual. Pastas de cimento vibroprensadas com baixa relação água-cimento (padrão, 3% pigmento, 15% RCV e 3% pigmento – 15% RCV) também foram moldadas para avaliações de cunho microestrutural, cristalográfico e de análise térmica das reações de hidratação dos sistemas. O traço padrão foi 1:2,29:1,76:0,95 (cimento:areia média:areia muita grossa:pedrisco) com relação água-materiais secos 0,80. De uma maneira geral, adições de apenas pigmento (2% e 4%) reduziram em até 73% a resistência à compressão do paver padrão cinza (sem adições). Redução nos produtos de hidratação (CH e C-S-H) foram observadas. As substituições de areia média pelo RCV também foram prejudiciais a esse sistema. Já as adições de apenas RCV, bem como as de RCV concomitantemente com pigmento foram positivas em ganhos ou manutenção de propriedades (resistência à compressão, absorção de água, resistência à abrasão e cor) em relação ao paver padrão colorido (4% de pigmento), destacando-se a formulação 2% de pigmento e 50% de RCV. Assim, a adição de RCV é uma possibilidade técnica promissora, sustentável e economicamente viável na fabricação de pavers avermelhados.
Concrete interlocking blocks colored with pigment iron oxide (red) are used in urbanization projects. However, that kind of pigment increases around 20 to 30% the value of the pavers, as well as affect the properties of the dry concrete molded by vibrocompression. Therefore, it is proposed to incorporate red ceramic waste (RCW) as colorimetric hue in order of pigment content reduction in colored pavers, considering also the possibility of improving their properties by filler and pozzolanic effect. In order to investigate the effect of pigment and RCW in the studied composite, the formulations were: (a) reference paver designed by ABCP method for blocks and pavers; (B) adding pigment to the reference paver (2% and 4%); (C) substitution of medium sand by RCW in the reference paver (50%, 75% and 100%); (D) adding RCW in the reference paver (20%, 30%, 40% and 50%); (E) addition of pigment (2%) and RCW concurrently in the reference paver (20%, 30%, 40%, 50%, 100% and 150%). For all mixtures (except those of replacement formulations), it was made the correction in cement consumption related to the reference mix proportion. Compressive strength, water absorption and abrasion resistance were measured according to the ABNT NBR 9781: 2013 standards; besides that, the color and texture of all manufactured formulations were observed by visual inspection. Cement pastes made by vibrocompression with low water-cement ratio (reference paste, 3% pigment, 15% RCW and 3% pigment RCW - 15% RCW) were also molded for microstructural, crystallographic and thermal analysis of systems hydration reactions. The reference mix proportion was 1:2.29:1.76:0.95 (cement: medium sand: thick sand: gravel) with ratio water-dry material 0.80. In general, additions of only pigment (2% and 4%) up to 73% reduced the compressive strength of the reference paver (no additions). Reduction in hydration products (C-S-H and CH) was observed. The substitution formulations of medium sand by RCW were also harmful to the systems. Additions of only RCW and RCW concomitantly with pigment were positive in gains or maintaining of properties (compressive strength, water absorption resistance and abrasion resistance) compared to the reference colored paver (4% pigment), especially the formulation of 2% pigment and 50% RCW. Thus, the addition of RCW is a promising, economic and sustainable technique in the production of red pavers.
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Magalhães, Fábio Costa. "Estudo probabilístico da resistência à compressão e da resistência à tração na flexão dos concretos utilizados na construção do dique seco do estaleiro Rio Grande, no superporto, em Rio Grande - RS." reponame:Repositório Institucional da FURG, 2009. http://repositorio.furg.br/handle/1/3444.
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Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia Oceânica, Escola de Engenharia, 2009.Submitted by Lilian M. Silva (lilianmadeirasilva@hotmail.com) on 2013-04-20T22:47:54Z No. of bitstreams: 1 Estudo probabilístico da resistência à compressão e da resistência à tração na flexão dos concretos utilizados na construção do dique seco do estaleiro Rio Grande, No Superporto, Em.pdf: 10848965 bytes, checksum: 809b5f8cbee32e8c634ff304349206bb (MD5)
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Made available in DSpace on 2013-06-04T16:19:35Z (GMT). No. of bitstreams: 1 Estudo probabilístico da resistência à compressão e da resistência à tração na flexão dos concretos utilizados na construção do dique seco do estaleiro Rio Grande, No Superporto, Em.pdf: 10848965 bytes, checksum: 809b5f8cbee32e8c634ff304349206bb (MD5) Previous issue date: 2009
A variação presente nos ensaios de aceitação do concreto, sobretudo a resistência, torna fundamental a utilização de uma grande quantidade de dados amostrais para estabelecer parâmetros de avaliação e calibração das normas técnicas. Distintos controles tecnológicos, metodologias de dosagem e características dos materiais, são alguns dos fatores que fazem com que o concreto tenha peculiaridades relacionadas à região do planeta onde o mesmo é produzido.O presente trabalho aplicou diversos métodos de controle e aceitação de estruturas de concreto aos resultados práticos oriundos do concreto lançado na execução do dique seco do Estaleiro Rio Grande em construção na cidade de Rio Grande - RS. Esta obra é uma importante fonte de informações sobre a resistência e o comportamento do concreto visto que, na mesma, foi empregado desde o início um rigoroso controle de qualidade; gerando dados raramente disponíveis em obras portuárias brasileiras. Foram utilizados como base para este trabalho dois traços de concreto; um com adição de fibras e fck= 35 MPa e outro com adição de sílica ativa e fck= 40 MPa. Foram realizadas comparações entre as estimativas de resistência das normas brasileira, européia e norte-americana de concreto. Realizadas análises estatísticas de modelos teóricos de distribuição de probabilidade destas resistências. Além disso, foram estabelecidas correlações entre as resistências à tração e à compressão do concreto. O incremento de resistência do concreto ao longo do tempo também foi estudado, tanto para compressão como para a tração. As análises apresentadas permitem atestar o atendimento dos concretos utilizados na execução do dique seco quanto aos requisitos estabelecidos pelas normas brasileiras de concreto.
Due to the variability in the results of the concrete acceptance tests, especially in the resistance tests, it is fundamental to use a large number of sample data to establish the assessment parameters and to calibrate the standard codes. Different technological controls, mixing methodologies and material characteristics are some of the factors that cause the concrete having peculiarities proper of the region where it is produced. The present work has applied different methodsof control and acceptance of concrete structures to the test results of the concreteused in the construction of the Estaleiro Rio Grande dry-dock, in the city of Rio Grande – RS. This construction site is an important source of information about the concrete resistance and behavior, because it was adopted, since the beginning of the construction, a rigorous quality control. This quality control produced a number oftest results that is seldom available in the Brazilian harbors construction sites. In this work two different concrete mixes were studied: first a fiber reinforced concrete (FRC) with fck = 35 MPa, and a second one with silica fume addition with fck = 40 MPa. The resistance assessment formulations of the Brazilian, European and North American standard codes were compared. A statistical analysis of best the probability distribution models for the resistance test results was made. Besides, it was determined a correlation between the concrete tensile and compressive resistances. The increasing of the concreteresistance with time was also studied to compression as well as to tension. The analyses performed have showed that both concrete mixes used in the construction of this dry-dock have attained the quality standards required by the Brazilian standard codes for concrete.
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Yin, Kexin. "Influence of clay fraction on the mechanical behavior of a soil-concrete interface." Thesis, Ecole centrale de Nantes, 2021. http://www.theses.fr/2021ECDN0015.
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L’interface sol-structure est un aspect important des intéractions entre le sol et la structure car elle permet d’assurer en grande partie la stabilité de la structure concernée. Le comportement mécanique de l’interface joue un rôle significatif dans le dimensionnement des structures de génie civil et dans la prédiction de leur comportement dans le temps. L’interface entre le sol et la structure est une fine couche de sol en contact avec la structure, dans laquelle des contraintes et des déformations se développent. A notre connaissance, les travaux précédents de la littérature qui caractérisent le comportement mécanique de cette interface concernent principalement des sols types tels que sable et argile ou des matériaux naturels, en contact avec des matériaux structurels tels que le béton, le bois ou l’acier. Cependant, les sols naturels sont très complexes, en partie dû aux hétérogénéités qu’ils contiennent et à leur histoire géologique, et la réponse mécanique des sols type ne permet pas toujours de représenter celles des sols naturels, ni celle de sols intermédiaires. Le comportement mécanique de sols intermédiaires entre sable et argile a été largement étudié, cependant celui de l’interface entre ces sols et un matériau structurel n’est que peu représenté, alors que la réponse de l’interface soumise à un chargement mécanique est bien différente de celui du sol seul. De plus, à l’échelle de l’ingénieur, il y a clairement un manque d’informations sur le comportement de cette interface le long d’une fondation chargée dans ces sols intermédiaires, numériquement et expérimentalement, ceci étant en partie lié aux difficultés d’instrumentations in-situ le long des foundations. L’objectif de cette thèse est de caractériser le comportement mécanique de l’interface entre le sol et la structure pour des sols intermédiaires entre le sable et l’argile. Des mélanges artificiels de sable de silice et d’argile riche en kaolinite ont été choisis pour représenter les sols intermédiaires. La thèse est d’abord composée d’une campagne expérimentale d’essais de cisaillement direct d’interface en laboratoire, afin d’identifier le rôle de la fraction massique d’argile sur le comportement mécanique d’une interface sol-béton. Une attention particulière a été apportée sur le montage expérimental et sur la préparation optimisée des échantillons de sol. Les résultats ont ensuite été utilisés dans une campagne de modélisation à l’échelle de l’ingénieur, visant à réprésenter le comportement mécanique de l’interface autour d’un pieu chargé latéralement. Une nouvelle routine MATLAB en éléments finis a été implémentée pour modéliser le comportement de cette interface par des courbes p y. La caractérisation du comportement mécanique de l’interface sol structure pour des sols à fraction massique d’argile variable a permis de mieux mettre en lumière le rôle de la microstructure de l’interface, sur la stabilité des structures de génie civilIn geotechnical engineering, the soil-structure interface is an important aspect to take into account in soil structure interactions because it relates to the stability of the supported structure. In particular, the mechanical behaviour of the interface plays a key role in the design of civil engineering structures and their analysis over time. The interface is a thin zone of soil in contact with the structure where major stresses and strains develop in. To our knowledge, previous works on the characterization of the mechanical behaviour of the soil-structure interface mainly include typical soils (sand or clay) or natural soils, in contact with variable structural materials (concrete, steel, wood). However, natural soils are very complex, partly due to geological heterogeneities, and the mechanical response of typical soils do not always represent accurately intermediate soils between sand and clay. Previous studies on the mechanical behavior of those soils are significantly represented in the literature, especially in experimental research, however it is rather poorly documented on the interface between these soils and structural materials, whereas their response to mechanical loadings is different. Moreover, at the engineering scale, there is still a lack of understanding on how this interface behave along loaded pile within soils between sand and clay, numerically, and experimentally due to instrumentation restrictions along the pile. The objective of this thesis is to characterize the mechanical behaviour of the soil-structure interface for intermediate soils between sand and clay, both by experiments at the laboratory scale and by models at the engineering scale. Artificial mixtures of silica sand and kaolinite-rich clay are chosen to represent intermediate soils in this study. For this propose, the research is organized in a first and main experimental campaign that aims to investigate the effect of the clay content, from 0% (sand) to 100% (clay) on the mechanical behavior of a soil-concrete interface by a new interface direct shear device in the laboratory. A particular attention is given to the design of the setup, and to the investigation of four sample preparations to insure an optimize sample homogeneity. A second and numerical campaign is performed to input the results from the experimental campaign, to model the mechanical response of the interface between sand-clay soils and a lateral concrete loaded pile at the engineering scale. A new subroutine of a MATLAB finite element code is implemented to perform the numerical modelling of the interface’s response via the p-y curves. The characterization of the mechanical behaviour of the soil-structure interface at different clay and sand fractions allows to enlighten the role of soil microstructure at the soil-structure interface on the stability of civil engineering structures
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Felipe, Alexsandro dos Santos [UNESP]. "Contribuição para a otimização de traços de concreto utilizados na produção de blocos estruturais." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/91466.
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felipe_as_me_ilha.pdf: 2392820 bytes, checksum: 9c6e04fef232018e3760dee715984441 (MD5)Universidade Estadual Paulista (UNESP)
Diante do grande crescimento da alvenaria estrutural no país, muitas fábricas de blocos de concreto vieram por necessidade, buscar por otimizações do seu processo produtivo, visto que, projetos mais arrojados, acabam exigindo maiores controles de qualidade. A proposta deste estudo é melhorar a produção destes artefatos de concreto por meio de otimizações simples que reduzem o custo e garantem uma produção eficiente na fábrica. Estudar a fundo os vários parâmetros de formação de um traço de concreto seco, tais como coesão, textura, energias de adensamento e resistência à compressão axial, todos os fenômenos dependentes entre si, torna-se muito complexo se avaliado em um único trabalho. No entanto, propor um estudo que colete informações apresentadas por vários autores, facilita na otimização e criação de uma pesquisa que possa contribuir na dosagem para concretos secos, em especial, na fabricação de blocos estruturais. Neste estudo, adaptaram-se para laboratório alguns equipamentos de uso comum para confecção destes artefatos de concreto, possibilitando a correlação direta de corpos de prova cilíndricos com os blocos. Uma das adaptações é o estudo baseado na padronização da energia de compactação, proporcionada pelo equipamento para ensaios de mini-proctor, simulando assim, a máquina vibro-prensa. Outras correlações como coesão e resistência à compressão, também foram possíveis de obter no laboratório, reduzindo então, as interferências constantes no processo produtivo da fábrica, ocasião verificada em vários outros estudos. Diante do exposto, foi possível avaliar com boa segurança os resultados. O estudo foi desenvolvido em três etapas, sempre buscando a maior massa específica seca compactada da mistura de agregados, inicialmente na primeira etapa, foi utilizado somente dois agregados (areia fina e pedrisco), conforme...
Given the substantial growth of structural masonry in Brazil, many concrete block companies have seen the need to optimize their production process, since more challenging projects require greater quality control. This study proposes to improve the production of concrete artifacts by means of simple optimizations that reduce costs and ensure the company’s efficient production. Studying in depth the various parameters of the formation of dry concrete trace, such as cohesion, texture, density energy and axial compressive strength, all the particularities interdependent on one another become very complex when assessed in a single study. However, proposing a study that collects the information submitted by various authors, expedites optimizing and creating a research study which may assist in improving the dosage for dried concrete, particularly in the manufacture of structural blocks. In this study, some commonly used manufacturing equipment, such as concrete artifacts, were laboratory-adapted, enabling a direct correlation of the cylindrical specimens with the blocks. One of the adjustments is the study based on the standardization of compaction energy, provided by the mini-proctor testing equipment, thus simulating the vibro press machine. Other correlations such as cohesion and compressive strength were also obtained in the laboratory, therefore reducing the constant interferences in the plant’s production process, observed in many other studies. In this manner, it was possible to reliably assess the results. The study was conducted in three stages, always seeking the highest compressed dry specific mass of the mixture of aggregates. In the first stage, only two aggregates were used (fine sand and pebbles), commonly used at the plant. The second stage included adding the coarse sand and stone powder to correct the lack of resistance promoted by the high amount of fine sand from... (Complete abstract click electronic access below)
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Moretti, José Fernando [UNESP]. "Sistema inteligente baseado nas redes neurais artificiais para dosagem do concreto." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/100325.
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moretti_jf_dr_ilha.pdf: 2346139 bytes, checksum: 4b4bfcffd24744e4627ebd26e46f3196 (MD5)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O concreto é o material estrutural mais utilizado na construção civil. Há mais de um século e meio ele vem sendo estudado e aperfeiçoado. É confeccionado utilizando-se de matérias primas regionais, com características técnicas diferentes de outras regiões. O cimento também se apresenta com diversas formulações. Quantificar adequadamente esses materiais é o objetivo do estudo da dosagem do concreto, de tal modo a se obter um concreto que atenda às necessidades estruturais exigidas. Sendo a principal delas a resistência à compressão. A dosagem do concreto é uma prática essencialmente laboratorial quando se pensa em resultados aceitáveis. Através de experimentos são idealizados ábacos e diagramas que podem fornecer a resistência do concreto endurecido com diversas combinações de matérias primas utilizadas. Não há uma formulação matemática abrangente e bem definida para um processo generalizado de dosagem. A complexidade aumenta quando se adicionam outros componentes a mais no concreto simples e tradicional. Obter a relação entre eles é um trabalho contínuo. As redes neurais vêm sendo utilizadas na solução de problemas da engenharia civil, com ênfase na aplicação da técnica da retropropagação. Ela realiza satisfatoriamente as iterações entre as diversas variáveis, num processo de treinamento e aprendizagem, e tem sido capaz de generalizar soluções aceitáveis. Nesta pesquisa de doutorado é utilizada uma rede neural feedfoward com algoritmo retropropagação para prever a resistência e o módulo de elasticidade do concreto. Os dados de entrada são quantidades de materiais utilizadas para confeccionar 1 m3 de concreto adensado, de forma semelhante a dosagem por diagramas. Será aplicada na interpretação de diagramas de dosagem. Tais diagramas são amplamente utilizados por empresas na confecção de concretos,...
Concrete is the most widely used structural material in construction, for more than a century and a half it has been studied and improved. It's prepared using regional raw materials with different technical characteristics of other regions. The cement also performs with various formulations. Adequately quantify these materials is the goal of the study of the concrete mixtures proportion, to obtain a concrete that meets the structural needs required. The main one being the compressive strength. The strength of concrete is essentially a practice laboratory when one considers acceptable results. Through experiments are idealized abacus and diagrams that can provide the strength of hardened concrete with various combinations of raw materials used. There is no mathematical formulation of comprehensive and well defined for a generalized process of mixes. The complexity increases when other components is added in the most simple and traditional concrete. Obtain the relationship between them is a work in progress. Neural networks have been used in solving engineering problems, with emphasis on applying the technique of backpropagation. It performs satisfactorily iterations between the different variables in a process of training and learning, and has been able to generalize acceptable solutions. In this work is used a feedforward neural network with backpropagation algorithm to predict the compressive strength and modulus of elasticity of the concrete. The input data are quantities of materials used to fabricate 1,0 m3 of concrete hardened, similar dosing for diagrams and abacus. Such diagrams are widely used by companies in the manufacturing of concrete, yielding good precision in the final results. They are produced on the vast experience with the same materials and are highly regional representative to provide subsidies for training neural networks. This... (Complete abstract click electronic access below)
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Bezerra, Débora Morais. "Avaliação do desempenho de catalisadores obtidos de hidrotalcitas na reforma seca do metano." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-08032017-163957/.
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Catalisadores ativos e estáveis, preparados a partir dos hidróxidos duplos lamelares (HDLs) contendo os cátions Ni2+, Zn2+, Al3+ e Zr4+(NiZn-Al, NiZn-AlZr e NiZn-Zr), foram avaliados na reação de reforma seca do metano. Os precursores foram caracterizados por difração de raios X, confirmando a formação das fases para as amostras de NiZn-Al e NiZn-AlZr. As espectroscopias no infravermelho/Raman elucidaram a ocorrência dos ânions (CO32-) e das moléculas de água na intercamada. A Fisissorção de nitrogênio ( método de BET) determinou a presença de poros e a área superficial específica. As formas das isotermas foram do tipo IV, de acordo com a IUPAC, e representa uma estrutura mesoporosa. A análise termogravimétrica foi utilizada para determinar a temperatura de calcinação dos precursores para obtenção dos catalisadores e as temperaturas utilizadas foram 550 °C, 650 °C e 750 °C. Os resultados de difração de raios X dos catalisadores apresentaram uma mistura de óxidos binários (NiO, ZnO, ZrO2 e Al2O3) e óxidos ternários (NiAl2O4 e ZnAl2O4). As fases de espinélios foram observadas nos catalisadores obtidos a 650°C (Ni/ZnAl-6 e Ni/ZnAlZr-6) e 750°C (Ni/ZnAl-7 e Ni/ZnAlZr-7). A redução a temperatura programada de hidrogênio (TPR-H2) forneceu informações sobre a redução do catalisador. Os resultados exibiram interações entre a fase ativa com as outras fases presentes no intervalo entre 350 - 800 °C, enquanto que a dessorção àtemperatura programada de CO2 (DTP-CO2) mostrou que os catalisadores possuem sítios básicos fracos. Ademais, os catalisadores foram caracterizados por fisissorção de nitrogênio, microscopia eletrônica de varredura (MEV), espectroscopia Raman e basicidade usando um indicador de Hammett. O desempenho dos catalisadores foi avaliado na reação de reforma seca do metano utilizando uma razão molar de alimentação de CH4: CO2 = 1,5:1,0; a fim de simular a composição do biogás. Os resultados mostraram uma maior conversão para o CO2 em todos os catalisadores investigados, o que pode ser atribuído ao maior teor de CH4 alimentado. Além disso, é importante ressaltar a contribuição dos sítios básicos presentes nas amostras, o que pode também contribuir para a conversão do CO2. A maior conversão de CH4 foi observada para os catalisadores tratados a 750 °C. Após as reações, foi observada a formação de carbono grafite sobre todos os catalisadores, com menor percentual para a amostra Ni/ZnAl, calcinadas a 550 °C e 650 °C, e Ni/ZnZr-7, calcinada a 750 °C. Finalmente, os catalisadores calcinados a 650 °C e 750 °C também foram ativados na temperatura de 750°C e os resultados reacionais mostraram que essa temperatura favoreceu o processo de aglomeração e, portanto, promoveu baixas conversões para o CH4 e CO2.Active and stable catalysts, prepared from the lamellar double hydroxides (HDLs) containing the cations Ni2 +, Zn2 +, Al3 + and Zr4 + (NiZn-Al, NiZn-AlZr and NiZn-Zr) were evaluated in the dry reforming reaction of methane. The precursors were characterized by X-ray diffraction method, confirming the formation of phases for NiZn-Al and NiZn-AlZr samples. Infrared / Raman spectroscopies elucidated the occurrence of anions (CO32-) and water molecules in the interlayer. Nitrogen physisorption (BET method) determined the presence of pores and the specific surface area. The shape of the isotherms were type IV, according to the IUPAC, representing a mesoporous structure. The thermogravimetric analysis was used to determine the calcination temperature of the precursors to obtain the catalysts and the temperatures used were 550 ° C, 650 ° C and 750 ° C. The X-ray diffraction results of the catalysts showed a mixture of binary oxides (NiO, ZnO, ZrO2 and Al2O3) and ternary oxides (NiAl2O4 and ZnAl2O4). The spinel phases were observed in the catalysts obtained at 650 °C (Ni/ZnAl-6 and Ni/ZnAlZr-6) and 750°C (Ni/ZnAl-7 and Ni/ZnAlZr-7) Temperature- programmed reduction with hydrogen (H2-TPR) provided information on catalyst reduction. The results showed interactions between the active phase and the other phases present in the range of 350 - 800 ° C, while temperature- programmed desorption of CO2 (CO2-TPD) showed that the catalysts have weak basic sites. In addition, the catalysts were characterized by Nitrogen physisorption, scanning electron microscopy (SEM), Raman spectroscopy and basicity using a Hammett indicator. The performance of the catalysts was evaluated in the dry reforming reaction of the methane using a CH4: CO2 molar feed ratio = 1.5: 1.0; In order to simulate the biogas composition. The results showed a higher conversion to CO2 in all the catalysts investigated, which can be attributed to the higher content of CH4 fed. In addition, it is important to restate the contribution of the basic sites present in the samples, which may also contribute to the conversion of CO2.The higher conversion of CH4 was observed for the catalysts treated at 750 ° C. After the reactions, the formation of graphite carbon was observed on all the catalysts, with a lower percentage for Ni / ZnAl samples, calcined at 550 ° C and 650 ° C, and Ni / ZnZr-7, calcined at 750 ° C. Finally, the catalysts calcined at 650 ° C and 750 ° C were also activated at the temperature of 750 ° C. and the reaction results showed that this temperature favored the agglomeration process and, therefore, promoted low conversions for CH4 and CO2.
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Černý, Jan. "Dvoušnekový mísič kontinuální." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-433469.
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This work focuses on the process of mixing particulate materials and the design of the screw mixer for this activity. The theoretical part describes the mixing and properties of particulate matter. Subsequently, individual devices serving for different types of mixing are analyzed. The practical part contains calculations of the main dimensions and the required power consumption. The choice of suitable drive, bearings and gear is followed. Finally, the analysis of the blade shaft load and the strength analysis of the mixer blade using Autodesk Inventor are performed. Part of this work is enclosed drawing documentation of equipment assembly and selected partial components.
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Skřivánek, Michal. "Návrh technologie vodopropustných betonů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-295663.
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My work describes technology design of pervious concrete. The theoretical part contains a research about this kind of concrete usually from foreign authors. In general, I focused on the composition of the PC, aggregate grading curve, behaviour of concrete in fresh state, storing and compaction of concrete. A critical part is the aggregate grading curve – it plays the main role in the final level of water permeability. Further, we will go through the real world scenarios where we can use this type of concrete and also through the associated drawbacks. A substantial part of this work is about development of water-permeability test. The practical part shows variety of recipes with a list of measured and observed characteristics (compressive strength, frost resistence and water-permeability). The conclusion includes evaluation of the results and suggestions for future development in this area.
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Ouédraogo, Nongwendé Philippe. "Contribution à la valorisation de sédiments de dragage portuaire issus de lagunage actif dans la formulation de matériaux cimentaires autoplaçants." Thesis, Ecole nationale supérieure Mines-Télécom Lille Douai, 2019. http://www.theses.fr/2019MTLD0020.
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Les sédiments de dragage constituent une ressources granulaire minérale alternative d’abondance et stratégique pour le domaine de la construction. Ce travail doctoral s’intéresse spécifiquement aux sédiments de dragage portuaire de Grand Port Maritime de Dunkerque (GPMD), issus de lagunage actif. L’objectif de la recherche est d’évaluer le potentiel de valorisation de ces sédiments sortant directement des bassins de lagunage du GPMD, (déshydratés en partie, mais faiblement humides) dans la formulation de bétons autoplaçants (BAP), sans aucun traitement additionnel avant leur incorporation dans les matériaux cimentaires (ni étuvage, ni calcination notamment).Trois sédiments GPMD ont été retenus pour l’étude, leur différence étant marquée par leurs teneurs en fines à 63 µm, respectivement de l’ordre de 34, 43 et 49%. Du fait de leur fort pourcentage en particules inférieures à 125 µm et de leur distribution granulométrique, l’intérêt de l’étude réside également dans l’évaluation de l’aptitude des sédiments à substituer les fillers minéraux naturels classiquement utilisés dans la composition de matrices cimentaires autoplaçantes.Un protocole expérimental spécifique est développé pour s’affranchir de la problématique de présence d’agglomérats de sédiments dans les matrices cimentaires.La méthodologie expérimentale globale de formulation s’articule autour de la méthode DMDA (Densified Mixture Design Algorithm) pour la composition des BAP, la méthode de l’AFREM et la méthode de la pâte équivalente. Sur l'ensemble des formulations réalisées, les performances physico-chimiques, rhéologiques, mécaniques, environnementales ainsi qu'une première approche de la durabilité vis-à-vis du gel-dégel sont étudiées. Les influences des fines de sédiments sur les performances mécaniques et la résistance au gel/dégel sont plus nuancées, les performances globales des matrices étant néanmoins avérées. D'un point de vue environnemental, les BAP développés sont classés comme matériaux inertesDredging sediments are an abundant and stand for a strategic alternative mineral granular resource in construction. This PhD work specifically focuses on the Grand Port Maritime de Dunkerque (GPMD) dredging sediments, resulting from an active lagooning. The research objective is to evaluate the potential for recovery of these sediments coming directly from the GPMD lagoon basins (partly dehydrated but poorly moist) in the formulation of self-consolidating concretes (SCC), without any additional treatment before their incorporation into the cementitious materials (without drying, nor calcination in particular).Three GPMD dredging sediments were selected for the study, their difference being their fines content at 63 μm, respectively of the order of 34, 43 and 49%. Because of their high percentage of particles smaller than 125 μm and their particle size distribution, the interest of the study also lies in the assessment of the ability of sediments to substitute the natural mineral fillers conventionally used in the composition of SCC.A specific experimental protocol is developed to overcome the problem of presence of sediment agglomerates in cementitious matrices. The overall experimental formulation methodology is based on the Densified Mixture Design Algorithm (DMDA) method for the determination of SCC compositions, the AFREM method and the equivalent paste method. On the set of formulations carried out, the physical-chemical, rheological, mechanical and environmental performances as well as a first approch of the durability with regard to freeze-thaw are studies. The influences of sediment fines on mechanical performance and freeze / thaw resistance are more nuanced, although the overall performance of the matrices is proven. From an environmental point of view, the developed SCCs are classified as inert materials
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Líšková, Jana. "Navrhování nízkoteplotních asfaltových směsí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409814.
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In this diplomatic work, the issue of low-temperature asphalts and binders for asphalt mixtures is solved. Diploma work is divided into two parts, theoretical and practical. In the theoretical part of diploma work, the purpose was to process a overview of technologies that allow the reduction of working temperature in the production and laying of asphalt mixtures. The purpose of the practical part was to comparison the functional parameters of two types of asphalt mixtures made in two variants, with the common asphalt binder and adding licomont into asphalt. Attention was given to stiffness, wheel drive tests and low temperature parameters.
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Ji, Xiaoyan. "Thermodynamic properties of humid air and their application in advanced power generation cycles." Doctoral thesis, Stockholm : Department of Chemical and Engineering and Technology, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4129.
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Amorim, Natalia Meira de Moura. "Estudo da formula??o de pr?-misturas secas para a cimenta??o de po?os em terra." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12993.
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Previous issue date: 2013-09-02Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
An economical solution for cementing oil wells is the use of pre-prepared dry mixtures containing cement and additives. The mixtures may be formulated, prepared and transported to the well where is added water to be pumped.Using this method, becomes dispensable to prepare the cement mixes containing additives in the cementing operation, reducing the possibility of error. In this way, the aim of this work is to study formulations of cement slurries containing solid additives for primary cementing of oil wells onshore for typical depths of 400, 800 and 1,200 meters. The formulations are comprised of Special Class Portland cement, mineral additions and solids chemical additives.The formulated mixtures have density of 1.67 g / cm ? (14.0 lb / gal). Their optimization were made through the analysis of the rheological parameters, fluid loss results, free water, thickening time, stability test and mechanical properties.The results showed that mixtures are in conformity the specifications for cementing oil wells onshore studied depths
Uma solu??o econ?mica para a cimenta??o de po?os de petr?leo ? o emprego de pr?- misturas secas contendo cimento e aditivos s?lidos. As misturas podem ser formuladas, preparadas e transportadas para o po?o onde ser? adicionada ?gua para bombeio. Com essa metodologia, torna-se dispens?vel a prepara??o das misturas de cimento com aditivos no ato da opera??o de cimenta??o, reduzindo a possibilidade de erro. Desta forma, o objetivo desse trabalho ? estudar formula??es de pastas de cimento contendo aditivos s?lidos para a cimenta??o prim?ria de po?os de petr?leo onshore para profundidades t?picas de 400m, 800m e 1.200 metros. As formula??es s?o constitu?das de cimento Portland Classe Especial, adi??es minerais e aditivos qu?micos s?lidos. As misturas formuladas possuem massa espec?fica de 1,67 g/cm? (14,0 lb/gal). Sua otimiza??o foi feita a partir da an?lise de resultados de reologia, comportamento de perda de fluido para a forma??o, forma??o de ?gua livre ambiente, tempo de espessamento, estabilidade da mistura e comportamento mec?nico. Os resultados mostraram que as misturas se adequam ?s especifica??es para a cimenta??o de po?os de petr?leo onshore nas profundidades estudadas
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Lessard, Jean-Martin. "Optimisation des cendres volantes et grossières de biomasse dans les bétons compactés au rouleau et dans les bétons moulés à sec." Mémoire, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/8831.
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Résumé : Depuis le début du XXe siècle, la production de bétons secs représente une industrie importante pour le développement des infrastructures en bétons compactés au rouleau notamment pour la construction de barrages, de digues, de pavages, et les bétons moulés à sec pour la pré-fabrication de blocs de maçonnerie, de briques, de pierres de pavé, etc. La durabilité de celles-ci peut être améliorée en réduisant leur consommation de ciment Portland et de granulats naturels en utilisant, respectivement, des ajouts cimentaires et des matériaux granulaires alternatifs. D’ailleurs, beaucoup de sous-produits industriels et autres ajouts cimentaires alternatifs ne respectant pas les exigences pour le béton conventionnel ont été utilisés avec succès dans ce type de béton. Les cendres de biomasse sont des sous-produits prometteurs pour les applications de bétons secs. Ces cendres sont obtenues dans une centrale de cogénération de l’industrie des pâtes et papiers suite à la combustion de leurs boues de traitement des eaux usées, de leurs boues de désencrage, et autres résidus de bois. Les cendres volantes de biomasse (CVB) ont une finesse similaire à celle du ciment et elles possèdent aussi un potentiel de réactivité pouzzolanique. Elles peuvent donc remplacer une partie du ciment utilisé dans la formulation de bétons. Les cendres grossières de biomasse (CGB) ont une granulométrie voisine de celle d’un sable fin. Elles peuvent donc être valorisées en remplaçant une partie des granulats naturels utilisés dans les formulations de bétons. Bien que les propriétés physico-chimiques et les interactions cimentaires de celles-ci soient étudiées depuis le début des années 2000, très peu d’applications commerciales ou industrielles ont été développées. Ce projet de recherche vise l’étude et l'optimisation des CVB comme ajout cimentaire alternatif et des CGB comme granulats fins alternatifs dans la production de bétons compactés au rouleau (BCR) et à la paveuse (BCP) pour des applications de pavages industriels et dans la production de bétons moulés à sec (BMS) pour des applications de préfabrication de pierres de pavé. Pour chacune de ces applications, des formulations incorporant un taux de substitution jusqu'à 30% du ciment par des cendres volantes et jusqu’à 100% du sable par des cendres grossières ont été réalisées. Ces travaux d’optimisation ont été effectués avec des bétons à rap-port eau-liant de 0,32, 0,35 et 0,37. Les propriétés à l’état frais (maniabilité et consistance), à l’état durci (résistance à la compression, à la flexion et à la traction), et de durabilités (absorption à l’eau, vides perméables et résistivité électrique) jusqu'à 91 jours ont été mesurées pour tous les mélanges de béton. Le rapport eau-liant, la teneur en pâte et les taux de remplacement optimaux ont également été combinés et optimisés afin de valoriser un maximum de cendres de biomasse, volantes et grossières, dans une seule formulation. Les résultats des mélanges de BCR fabriqués en laboratoire avec 10% et 20% de CVB et combinés à 50% de CGB ont respectivement montré des maniabilités désirées et des résistances à la flexion supérieures aux limites prescrites par les devis techniques pour une utilisation pratique de 23% et 29%. Ces deux mélanges donc ont été sélectionnés pour évaluer leur comportement in situ à l’aide de la construction d'une dalle de stockage de 792 m² par 300 mm d'épaisseur à l'aide de pratiques courantes. Des carottes ont été prélevées dans la dalle à 28 et 308 jours. La résistance à la compression des noyaux à l'âge de 308 jours a atteint 33 et 30 MPa pour les deux mélanges testés, respectivement. Les BMS fabriqués avec 5%, 10%, ou 15% CVB et 25% de CGB peuvent atteindre un indice de compaction de 99% avec un travail de compaction inférieur à celui spécifié par les fabricants de pierre de pavés. L'utilisation des CVB et CGB entraîne une faible diminution de la résistance à la compression, mais présente des valeurs de perméabilité et d’absorption à l’eau très faibles et inférieures aux exigences requises les normes (près de 5%). Ces travaux de recherche présentent un débouché potentiel à la valorisation des cendres volantes et grossières de biomasse issues de l’industrie des pâtes et papiers dans les bétons secs comme ajout cimentaires ou granulats fins. Cette approche peut offrir une contribution significative pour la réduction des émissions de gaz à effet de serre associés à la production de ce type de béton et dans les gestions des matières résiduelles de l’industrie des pâtes et papiers.Abstract : Since the early twentieth century, the production of dry concrete is an important industry for infrastructure development including the construction of dams, core dikes, and pavements using roller-compacted concrete, and precast masonry blocks, bricks, pavers using dry-cast concrete. The sustainability thereof can be improved by reducing its consumption of Portland cement and natural aggregates using cementitious supplementary cementitious materials and alternative granular materials, respectively. Moreover, many industrial by-products and other mineral additions not meeting the requirements for conventional concrete have been success-fully used in such concrete. The biomass ashes are promising supplementary materials for dry concrete applications. These ashes are produced in a cogeneration plant of the pulp and paper industry following the burn-ing of their wastewater treatment sludge, their de-inking sludge, and other wood residues. The biomass fly ash (BFA) have a similar finesse in the cement and they also have a potential poz-zolanic reactivity. They may therefore replace part of the cement used in concrete formula-tions. The biomass bottom ashes (BBA) have a particle size close to that of a fine sand. They can be use to replace a portion of the natural aggregates. Although the physicochemical proper-ties and interactions with cement have been studied since the early 2000s, very few commer-cial or industrial applications have been developed. This research project aims at studying and optimizing the BFA content as an alternative sup-plementary cementitious materials and the BBA content as an alternative fine aggregates in the production of roller-(RCC) and paver-compacted concrete (PCC) for industrial pavements and dry-cast concrete (DCC) for the manufacture of pavers. Formulations incorporating substitu-tion rates of cement up to 30% by BFA and of the sand up to 100% by BBA were evaluated for each of the mentioned applications. This optimization work was carried out with concrete water-to-binder ratio (w/b) of 0.32, 0.35 and 0.37. The fresh properties (workability and com-pactness), hardened properties (compressive strength, flexural strength and splitting-tensile strength) and transport properties (water absorption, permeable voids and electrical resistivity) up to 91 days were measured for all concrete mixtures. The optimal w/b, paste content and replacement rates were also combined and optimized in order to maximize the biomass fly and bottom ashes content, in a single formulation. The results of concrete mixtures made with 10% and 20% BFA with 50% BBA showed 23% and 29% higher flexural strength than the limits required for practical use of RCC, respective-ly. These two RCC mixtures were selected for the assessment of in situ behaviors through the construction of a storage slab of 792 m² per 300 mm thick using standard practices. Core sam-ples were cut from the slabs at age of 28 and 308 days for follow-up of the concrete behavior with time. The compressive strength of the cores at an age of 308 days reached 33 and 30 MPa for the two tested mixtures, respectively. The DCC mixtures made with 5%, 10%, or 15% BFA and 25% of BBA can reach a compact-ness index of 99% with a compaction work lower than specified by the Standards. The use of the BFA and BBA lead to small decrease of the compressive strength, however they can result in very low permeability and water absorption values lower than required by the specifications (close to 5%). This research presents a potential market for recycling biomass fly and bottom ashes from the pulp and paper industry in dry concrete as alternative supplementary cementitious materials or fine aggregates. This approach can provide a significant contribution to reduce greenhouse gas emissions associated with the production of this type of concrete and with the managements of by-products from the pulp and paper industry.
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Moretti, José Fernando. "Sistema inteligente baseado nas redes neurais artificiais para dosagem do concreto /." Ilha Solteira : [s.n.], 2010. http://hdl.handle.net/11449/100325.
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Resumo: O concreto é o material estrutural mais utilizado na construção civil. Há mais de um século e meio ele vem sendo estudado e aperfeiçoado. É confeccionado utilizando-se de matérias primas regionais, com características técnicas diferentes de outras regiões. O cimento também se apresenta com diversas formulações. Quantificar adequadamente esses materiais é o objetivo do estudo da dosagem do concreto, de tal modo a se obter um concreto que atenda às necessidades estruturais exigidas. Sendo a principal delas a resistência à compressão. A dosagem do concreto é uma prática essencialmente laboratorial quando se pensa em resultados aceitáveis. Através de experimentos são idealizados ábacos e diagramas que podem fornecer a resistência do concreto endurecido com diversas combinações de matérias primas utilizadas. Não há uma formulação matemática abrangente e bem definida para um processo generalizado de dosagem. A complexidade aumenta quando se adicionam outros componentes a mais no concreto simples e tradicional. Obter a relação entre eles é um trabalho contínuo. As redes neurais vêm sendo utilizadas na solução de problemas da engenharia civil, com ênfase na aplicação da técnica da retropropagação. Ela realiza satisfatoriamente as iterações entre as diversas variáveis, num processo de treinamento e aprendizagem, e tem sido capaz de generalizar soluções aceitáveis. Nesta pesquisa de doutorado é utilizada uma rede neural feedfoward com algoritmo retropropagação para prever a resistência e o módulo de elasticidade do concreto. Os dados de entrada são quantidades de materiais utilizadas para confeccionar 1 m3 de concreto adensado, de forma semelhante a dosagem por diagramas. Será aplicada na interpretação de diagramas de dosagem. Tais diagramas são amplamente utilizados por empresas na confecção de concretos,... (Resumo completo, clicar acesso eletrônico abaixo)Abstract: Concrete is the most widely used structural material in construction, for more than a century and a half it has been studied and improved. It's prepared using regional raw materials with different technical characteristics of other regions. The cement also performs with various formulations. Adequately quantify these materials is the goal of the study of the concrete mixtures proportion, to obtain a concrete that meets the structural needs required. The main one being the compressive strength. The strength of concrete is essentially a practice laboratory when one considers acceptable results. Through experiments are idealized abacus and diagrams that can provide the strength of hardened concrete with various combinations of raw materials used. There is no mathematical formulation of comprehensive and well defined for a generalized process of mixes. The complexity increases when other components is added in the most simple and traditional concrete. Obtain the relationship between them is a work in progress. Neural networks have been used in solving engineering problems, with emphasis on applying the technique of backpropagation. It performs satisfactorily iterations between the different variables in a process of training and learning, and has been able to generalize acceptable solutions. In this work is used a feedforward neural network with backpropagation algorithm to predict the compressive strength and modulus of elasticity of the concrete. The input data are quantities of materials used to fabricate 1,0 m3 of concrete hardened, similar dosing for diagrams and abacus. Such diagrams are widely used by companies in the manufacturing of concrete, yielding good precision in the final results. They are produced on the vast experience with the same materials and are highly regional representative to provide subsidies for training neural networks. This... (Complete abstract click electronic access below)
Orientador: Carlos Roberto Minussi
Coorientador: Jorge Luís Akasaki
Banca: Anna Diva Plasencia Lotufo
Banca: Marco Antonio Morais Alcantara
Banca: David Calhau Jorge
Banca: Cesar Fabiano Fioriti
Doutor
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Nassar, Saif. "Evaluation of the Ohio CTE Device for Low Temperature Characterization of Hot Mix Asphalt." University of Akron / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1597158023589419.
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MENESES, Antônio Davi Barbosa de. "Concreto projetado como revestimento de túneis na Ferrovia Norte-Sul: análise segundo parâmetros de durabilidade." Universidade Federal de Goiás, 2010. http://repositorio.bc.ufg.br/tede/handle/tde/1327.
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Previous issue date: 2010-09-24The present work aims to analyse the durability parameters of the shotcrete, comparing the dry and wet projection systems, of the concrete resulting from the projection in plates and from the test specimens extracted from the tunnels structures of the North-South Railway, tract 01, in Anápolis-GO. This work considers an experimental research concerning the shotcrete behavior for dry-mix and wet-mix projection systems, by using testing indicators of the main durability parameters coming from national and international specifications. So, the experimental program involves a comparative assessment among the projection systems of current use in shotcrete, considering the comparative analysis between projected plates (control) and extracted test specimens from the tunnels on what refers to meeting the requirements related to durability. Therefore, the experimental program showed as independent variables: type of projection system (whether by means of dry-mix or wet-mix shotcrete) and the extraction of test specimen (from the control plates or from the tunnels structure). For each type of projection (dry-mix and wet-mix shotcrete), three plates were cast (normally used for concrete technological control) in conditions similar to the work-site, with the test specimens extraction been carried out according to pre-established ages. Eight test specimens were extracted from the just-builts tunnels generating thus samples to the durability associated tests, such as: capillary water absorption, immersion water absorption, concrete electric resistivity, water penetration under pressure, penetrability of chloride ions and concrete compressive strenght. Test specimens extracted from the tunnels and the from the plates were also submitted to testings of compressive strenght and mix-proportion reconstruction. The concrete extracted from tunnels showed worse results comparing to the parameters expected from the projected concrete requirements for road and rail tunnels, and it also demonstrated results which were inferior to the ones obtained from the plates. From a general assessment view, we could verify losses of durability properties of the shotcrete extracted from tunnels in reference to the projected plates.
O presente trabalho tem como objetivo analisar os parâmetros de durabilidade do concreto projetado, comparando os sistemas de projeção via seca e via úmida, dos concretos resultantes da projeção em placas e dos testemunhos extraídos das estruturas dos túneis da Ferrovia Norte-Sul, trecho 01, em Anápolis-GO. Este trabalho contempla um estudo experimental de análise do comportamento de concretos projetados por via seca e úmida, através de ensaios indicadores dos principais parâmetros de durabilidade, constantes das especificações nacionais e internacionais. O programa experimental envolve, portanto, a avaliação entre os sistemas de projeção de uso corrente em concreto projetado, considerando a análise comparativa entre as placas projetadas (de controle) e os testemunhos extraídos dos túneis, no que se refere ao atendimento aos requisitos relativos à durabilidade. Para tanto, o programa experimental teve como variáveis independentes: tipo de sistema de projeção (se por via seca ou por via úmida) e a extração dos corpos-de-prova de concreto (da placa ou do túnel). Para cada tipo de projeção (via seca e via úmida) foram moldadas três placas (normalmente utilizadas para os fins de controle tecnológico do concreto) em condições similares às da obra, tendo-se em seguida, nas idades preestabelecidas, executado-se a extração de corpos-de-prova. Foram também extraídos oito testemunhos dos túneis executados, gerando, assim, corpos-de-prova submetidos aos ensaios balizadores dos parâmetros de durabilidade adotados neste estudo, a saber: absorção de água por capilaridade, absorção por imersão e fervura, resistividade elétrica, penetração de água sob pressão, penetrabilidade de íons cloreto e resistência à compressão axial. Contribuíram também para a caracterização do material os corpos-de-prova extraídos dos túneis e das placas, que foram submetidos a ensaios de resistência à compressão axial e de reconstituição de traço. Os concretos extraídos dos túneis mostraram resultados abaixo dos parâmetros para os resultados esperados dos requisitos de concreto projetado para os túneis rodo-ferroviários, e ainda com resultados inferiores aos resultados obtidos das placas. Numa avaliação geral, constatou-se perdas de propriedades de durabilidade do concreto projetado extraídos dos túneis em referência aos das placas projetadas.
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Marinelli, Pietro. "QRA for LNG storage tanks: a comparison of different technological solutions." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Nell'elaborato è stato proposto un confronto in termini di rischio tra sei differenti soluzioni tecnologiche applicate alla zona di stoccaggio di impianti per la gestione di gas naturale liquefatto (LNG).
Si sono analizzate zone serbatoti con diverse tipologie di serbatoi tra cui single, double e full containment e differenti dimensioni e materiale del bacino di contenimento esterno. Sono state prese in considerazione anche le le tubazioni connesse ai serbatoi.
Per svolgere il confronto si è scelto di sviluppare un'analisi di rischio.
Come linee guida per l'analisi si è scelto di seguire le "Guidelines for Chemical Process Quantitative Risk Analysis", CCPS.
La metodologia prevede una prima fase di definizione del sistema e di identificazione dei pericoli, per passare poi all'analisi delle conseguenze con relativa stima delle frequenze di accadimento dei guasti che danno origine ai rilasci di materiale pericoloso.
Una delle fasi più importanti nell'analisi di rischio è senza dubbio la definizione degli scenari che possono generarsi in seguito all'innesco di un rilascio di sostanza pericolosa.
Dopo un'attenta valutazione e valendomi del supporto tecnico di esperti del settore, sono state individuate prima le tipologie di rilascio (rottura di serbatoi e/o piping) e in seguito gli scenari incidentali principali (pool fire, flash fire, jet fire e vapor cloud explosion).
Per il calcolo delle conseguenze e del rischio (espresso come frequenza annua di morte) è stato utilizzato Phast Risk 6.7, software in grado di calcolare intensità dell'effetto e probabilità di morte attorno alla sorgente di rilascio di materiale pericoloso.
Le frequenze di guasto dei componenti (serbatoti, piping, valvole, flange e connessioni strumentali) sono state estratte a partire dall'analisi di alcuni database.
I risultati trovati sono molto interessanti e mettono in luce l'importanza delle proprietà del materiale e delle dimensioni del bacino di contenimento esterno.
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Elalaoui, Oussama. "Optimisation de la formulation et de la tenue aux hautes températures d’un béton à base d’époxyde." Thesis, Cergy-Pontoise, 2012. http://www.theses.fr/2012CERG0577.
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La durabilité des matériaux employés en génie civil est remise en question par le vieillissement physico-chimique de ces matériaux pouvant engendrer des dégradations significatives qui peuvent mettre en péril la stabilité des structures du génie civil. Pour pallier à certains inconvénients des bétons hydrauliques, l'utilisation des matériaux composites à l'instar des bétons de résine, qui possèdent des qualités remarquables par rapport aux matériaux de construction conventionnels, s'avère très intéressant.À l'heure actuelle, les freins majeurs quant aux développements des bétons résines sont d'une part le coût de la résine dont le taux varie, selon l'application industrielle, de 5% à 25% et d'autre part leurs comportements aux températures élevées et au feu puisque les liants dans ces bétons sont des substances organiques qui résistent beaucoup moins à la chaleur que les matières inorganiques. L'objectif de l'étude est de favoriser le développement des bétons résines par la diminution du taux de la résine en optimisant les constituants du béton et l'amélioration de leurs ténues aux températures élevées par l'ajout des additions tout en assurant des performances mécaniques raisonnables. L'optimisation de la formulation du béton est menée sur deux étapes ; la première vise à optimiser le squelette granulaire (sable 0/4 et Gravier 4/10, silico-calcaires) expérimentalement en confrontant les résultats à ceux issus du modèle d'empilement compressible. La deuxième étape vise à optimiser la fraction massique du liant époxydique (6%, 9%, 13% et 16%) sur la base des essais de caractérisation mécaniques et physiques. Le deuxième objectif de l'étude a était menée par l'ajout des ignifugeants appartenant à deux familles différentes c'est-à-dire les hydroxydes de métal et les produits phosphorés inorganiques. Les propriétés physiques, thermiques et mécaniques des bétons additionnées et témoins, avant et après exposition à un cycle de chauffage-refroidissement de la température ambiante à une température de consigne de 100°C, 150°C, 200°C, 225°C et 250 °C avec une vitesse de montée fixée à 0.5°C/min, ont été évaluées par les techniques de caractérisation usuelles en plus des essais d'analyses chimiques et thermiques.Cette étude aboutit à la formulation d'un béton optimal en terme de composition et à évaluer l'effet de l'addition des ignifugeants surtout sur les propriétés thermiques et mécaniques.Mots clés : béton de résine, optimisation, température élevée, ignifugeants, propriétés mécaniques, propriétés physiques, propriétés thermiquesThe material used in civil engineering applications must be re-evaluated because of their physicochemical ageing which can generate significant damages and hence put the stability of civil engineering structures in danger.The replacement of the hydraulic concrete by composite materials as the polymer concrete which offer higher properties compared to conventional construction materials seems to be very interesting. At the present time, the major restrain for the development of polymer concrete are on one hand the cost of the polymer whose ratio varies according to the industrial applications between 5% and 25%, and on the other hand their behaviour when exposed to high temperatures or fire since the resin acting as binder in these polymer concretes are organic substances which are more sensitive to heat than the inorganic matters as cement.The aim of this study was to help the development of polymer concrete by optimizing the formulation and improving their behaviour when exposed the high temperatures by incorporating additions while keeping acceptable mechanical performances.The optimisation of the formulation is done in two steps; the first step consists of optimising the aggregates content (Natural River sands 0/4 mm and crushed gravels 4/10 mm). Experimental results are compared to those given by means Compressible Packing Model. The second step consists of optimizing the amount of polymer (6%, 9%, 13% et 16%) based on mechanical and physical tests.The second aim of this work was fulfilled by the incorporation of two flame retardants belonging to metal hydroxide and phosphorous components types. Physical, thermal and mechanical properties of concretes with or without flame retardant, before and after heating-cooling cycle from ambient temperature to exposure temperature of 100°C, 150°C, 200°C, 225°C et 250 °C with a rate of 0.5°C/min, are evaluated by common characterisation tests besides chemical and thermal ones. This study has leading to obtaining an optimum polymer concrete and evaluates the effect of flame retardant particularly on the thermal and mechanical properties.Keywords: polymer concrete, optimization, high temperatures, flame retardant, mechanical properties, physical properties, thermal properties
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Júnior, Renê Honório. "Dry joint between precast concrete elements." Master's thesis, 2016. http://hdl.handle.net/10362/20162.
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Lin, Yi-Yu, and 林奕妤. "Interlocking Effecton Performance of Porous Asphalt Concrete Mixture." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/73103602638963861417.
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Muras, Andrew J. "Prediction of Asphalt Mixture Compactability from Mixture, Asphalt, and Aggregate Properties." 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-05-7802.
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The underlying purpose of any pavement is to provide a safe, smooth and reliable surface for the intended users. In the case of hot mix asphalt (HMA) pavements, this includes producing a surface that is resistant to the principal HMA distress types: permanent deformation (or rutting) and fatigue damage (or cracking). To protect better against these distress types, there have recently been changes in HMA mixture design practice. These changes have had the positive effect of producing more damage resistant mixtures but have also had the effect of producing mixtures that require more compaction effort to obtain required densities. It is important to understand what properties of an HMA mixture contribute to their compactability. This study presents analysis of the correlation between HMA mixture properties and laboratory compaction parameters for the purpose of predicting compactability.
Mixture property data were measured for a variety of mixtures; these mixtures were compacted in the laboratory and compaction parameters were collected. A statistical analysis was implemented to correlate the mixture data to the compaction data for the purpose of predicting compactability. The resulting model performs well at predicting compactability for mixtures that are similar to the ones used to make the model, and it reveals some mixture properties that influence compaction. The analysis showed that the binder content in an HMA mixture and the slope of the aggregate gradation curve are important in determining the compactability of a mixture.
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Lin, Feng-Yih, and 林豐益. "Mixture proportion and quality of high performance concrete (HPC)." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/48208459801076856972.
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Lu, Su-Hsiu, and 呂夙修. "Application of Applied AI models in concrete mixture proportion." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/04998395925296353336.
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碩士國立交通大學
土木工程學系
99
Concrete is one of most utilized construction materials in civil and infrastructural engineering. Concrete is a highly sensitive material to the issues in production process, such as proportioning, mixing, pouring, curing, etc. Among those factors, propositioning is the most important aspect. However, concrete mix, designed based on conventional methods, are not guaranteed to satisfy the required aim. Meanwhile, if the concrete specimen test does not pass, it results in not only wasting cost, but also loss of time. Recently, computer-aided design of concrete mix proportioning is a feasible approach with the aspect of reducing the resource costs and increasing construction efficiency. Based on cost optimization approach, there are, currently, many schemes of computer-aided concrete mix proportioning design. However, cost is not the only aim for concrete mix design. This work attempts to employ K-Means algorithm to analyze the pre-collected database to design concrete mix proposition based on the predefined requirements and provide a diversity of design to satisfy requirements of engineering. In addition, ANN model can generate solutions, if K-Means algorithm cannot find solutions in database. Simulation results reveal that the system is feasible and practicable in concrete mix design.
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Liane, Shye-Sheng, and 梁協勝. "Large Size Aggregate In Asphalt Concrete To Evaluate Properties Asphalt Mixture." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/81912436433082492920.
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Chang, Chien-Lung, and 張乾龍. "The Study of Mixture and Fundamental Mechanics Properties of Heavy Concrete." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/74969345036205964117.
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碩士朝陽大學
營建工程系碩士班
88
Most of heavyweight concrete structures are designed for radiation protection, which constituent contains metal aggregate that is used to increase the unit weight of concrete and to absorb radiation. Once crack takes place in heavyweight concrete structures, not only the strength of the cracked structure has to be re-evaluated, but the crisis of radiation leakage will lead to be a crisis. In consequence, it is signficant to figure out the process how the crack is being developed, and that will be useful for detection, assessment and retrofitting for crack structure. This research attempts to investigate the mechanical properties and toughness of heavyweight concrete, and to inspect the mechanical behavior while the crack is propagating. The pre-cracked beam specimens and dye technique is used for crack analysis, which can reveal the development of real crack while the load is being applied. Thus, the strength of cracked specimens can be evaluated through those cracked sections. According to the results obtained from the test, the unit weight of heavyweight concrete increases with the increase of metallic aggregate inclusions, and the air content appears growing with the increase of iron ore content. The elastic modulus of heavyweight concrete also appears growing with the increase of iron ore content. On the other hand, it turns out that the velocity decreases with the increase of iron ore content. Fracture toughness of heavyweight concrete appears a little lower than normal concrete. From the dyed crack section, the crack depth of heavy concrete shows shorter in the middle portion than the outers, which is similar to that of normal concrete. The crack depth appears growing with the decrease of residual load capacity.
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Chen, Hung-Shing, and 陳泓炘. "Research on the mixture proportion of Low cement High Performence Concrete." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/21876393986466438432.
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碩士國立中興大學
土木工程研究所
83
In accordance with the conventional concrete mix design ,a high cement conten is an important factor required in the production of high strength concrete . However ,the test results of concrete made with the dry-mix ∕steam-injection procedure indicate that concrete made with a low cement content ( 250 kg/m^3 ) exhibits a high strength in an order of 60 MPa comparable to those of high strength concretes made with the wet mix procedure . It is therefore , envisioned that the conventional wet mix method may be improved to make high strength concrete with a low cement content . The proposed research will be carried out in two phases involving a theoretical study and an experimental test . In the first phase , the Kennedy material constitution law and the surface area method will be examined to optimize the mix design . In the second phase , different admixtures such as superplasticizers , water reducing agents and supplemental cementitious materials will be recorded , of which the data will be carefully studied to develop an effective mix technique . The objective of the proposed project is to conduct a feasibility study on minimizing the cement content in manufacturing high performence concrete . In order to provide useful reference for maintainable research and applied development , it is appropriate to figure out a mix proportion -ing method for high performence concrete with a low cement content through analyzing he test results .
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陳振欣. "Effect of monomer mixture on the properties of Polymer Impregnated Concrete." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/65279360447777822542.
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碩士國立海洋大學
材料工程研究所
87
MMA was used as monomer with different initiators and crosslinking agents in the polymerization process case. Mechanical properties and durability of polymer impregnated concrete have been investigated. Test results shows that：complete polymerization was observed in the concrete specimens whenever AIBN was used as initiator in the polymerized process at ambient condition and compresive strength ,elastic modulus and splitting-tensile strength of modified concrete were much better than those of normal concrete .In addition , durability improvement of modified concrete was verified by conducting chloride ion diffusion test and carbonation test .
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LI，CHUN-LUNG and 李俊龍. "Discussion on Mixture Proportioning Design and Performance of Green Pozzolanic Concrete." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/00418070730906623562.
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碩士中華大學
土木工程學系碩士班
102
Global warming and climate change cause frequent flooding, draught and typhoon disasters. Cause of the sustainable development of humans, energy conservation and carbon reduction are environmental protection priorities at the moment. Cement is the primary material emitting carbon dioxide. In response to the idea of environmental protection, this paper takes Pozzolanic “green” concrete production as the main development direction, to achieve the target of reducing cement content and carbon dioxide emissions, as well as producing strong concrete that has excellent performance. The research produces and analyzes 61 mixture proportions of green Pozzolanic concrete, using Pozzolanic material to replace a portion of cement and/or filler sand. The Pozzolanic material is locally-made slag and fly ash. The mixture proportioning design includes concrete test series of 3 different categories: the first is test series with Pozzolanic material content of 0%, 30% and 50%; the second is a green mixture proportioning which reaches 3000psi with a target strength requirement of 28 days; the third discusses the property change of Pozzolan in different proportional combinations. The research discusses compressive strength, cement strength efficiency, strength development rate, carbon footprint and so on. The concrete test cylinders’ compressive strength with a 28-day age has been able to reach 6122psi, and the one with a 56-day age has reached 7255psi; while the cement strength efficiency has been able to reach 28.8 psi/kg in its 28-day age, and 37psi/kg in its 56-day age. It is calculated that the designed green mixture proportioning which substitutes 50% of cement by slag has a 114kg/1m3carbon emission; however the traditional one has 327kg/1m3. The research results show that the green mixture proportioning has been able to reduce carbon emission by 65% at most. The final optimal green mixture proportioning design is provided as reference for relevant civil engineering units, and makes a contribution to carbon reduction application of concrete materials. Keywords: Pozzolan, carbon footprint, green mixture proportioning, green concrete
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Yi-Ying-Lan and 藍亦熒. "Jamming analysis of a binary dry granular mixture in a two-dimensional rotating hopper." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/87156232033604837705.
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碩士國立成功大學
土木工程學系
104
The purpose of the study is on the influence of mixed ratio of binary dry granular mixture on the jamming probability in a rotating 2D hopper. The 2D rotating hopper is self-constructed, with adjustable hopper slope and hopper opening. The elliptical grains with different aspect ratios are equally constructed. Both the hopper passage and elliptical grains are made of Plexiglass. The parameters in the experiment are the aspect ratio of the elliptical grains, the experimental slope θ, the other parameters such as grain material, rotating speed, amount of grains, the number of the experiment done, the arrangement of the grains etc. When the aspect ratio increases, the jamming probability increases corresponding, because the grains are relatively thin, therefore the contact points between the grains are increased. When the aspect ratio increases, it will increase the range of the arch numbers, because the higher aspect ratio of the grains is easier to occurs grains deflection phenomenon.