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1
Vaičienė, Marija. "Influence of the active additives on the structure and properties of expanded-clay lightweight concrete." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120119_143017-08407.
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Two active mineral additives were selected in the investigation described in the dissertation: unground catalyst from the reactor of catalytic oil cracking (CAT) and unburned mullite wool (MW). The possibilities to utilise these raw materials in the production of the expanded-clay lightweight concrete are not analysed yet. Main topic of the research: influence of the active mineral additives (CAT and MW) on the main characteristics of the expanded-clay lightweight concrete.<br>Disertacijoje aprašytuose tyrimuose buvo pasirinkti du aktyvūs mineraliniai priedai: nemaltas katalizatorius iš katalitinio naftos krekingo reaktoriaus (KAT) ir nedegta mulitinė vata (MV). Galimybės šias atliekas naudoti keramzitbetonio gamyboje iki šiol netirtos. Pagrindinė tyrimo tematika – aktyviųjų mineralinių priedų (KAT ir MV) įtaka pagrindinėms keramzitbetonio charakteristikoms.
2
Van, Rooyen Algurnon Steve. "Structural lightweight aerated concrete." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80106.
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Thesis (MScEng)--Stellenbosch University, 2013.<br>Cellular concrete is a type of lightweight concrete that consists only of cement, water and
sand with 20 per cent air by volume or more air entrained into the concrete. The two
methods used for air entrainment in cellular concrete are (1) the use of an air entraining
agent (AEA), and (2) the use of pre-formed foam. If pre-formed foam is used to entrain air
into the concrete the concrete is named foamed concrete and if an AEA is used the concrete
is termed aerated concrete. Depending on the type of application, structural or nonstructural,
cellular concrete can be designed to have a density in the range of range of 400
to 1800 kg/m3. Non-structural applications of cellular concrete include void and trench filling,
thermal and acoustic insulation. Structural applications of cellular concrete include pre-cast
units such as concrete bricks, partitions, roof slabs etc. Due to the high levels of air in
cellular concrete it is challenging to produce compressive strengths that are sufficient to
classify the concrete as structurally useful when non-autoclaving curing conditions are used.
The autoclaving process combines high temperature and pressure in the forming process,
which causes higher strength and reduced shrinkage. This process is also limited to
prefabricated units. Non-autoclave curing conditions include moist curing, dry curing,
wrapping the concrete in plastic, etc. However, now that the world is moving in an energy
efficient direction, ways to exclude energy-intensive autoclaving are sought. It has for
instance been found that the utilisation of high volumes of fly-ash in cellular concrete leads
to higher strengths which make it possible to classify the concrete as structurally useful.
Now, that there is renewed interest in the structural applications of the concrete a design
methodology using an arbitrary air entraining agent needs to be found. The research
reported in this thesis therefore attempts to find such a methodology and to produce aerated
concrete with a given density and strength that can be classified as structurally useful.
For the mix design methodology, the following factors are investigated: water demand of the
mix, water demand of the mix constituents, and the amount of AEA needed to produce
aerated concrete with a certain density. The water demand of the mix depends on the mix
constituents and therefore a method is proposed to calculate the water demand of the mix
constituents based on the ASTM flow turn table. Due to the complex nature of air
entrainment in concrete, the amount of air entrained into the concrete mix is not known
beforehand, and a trial and error method therefore had to be developed. The trial mixes
were conducted in a small bakery mixer. From the trial mixes estimated dosages of AEA
were found and concrete mixes were designed based on these mixes. The factors that influence the mix design and strength of aerated concrete include
filler/cement ratio (f/c), fly-ash/cement ratio (a/c) and design target density. Additional factors
that influence the strength of aerated concrete are specimen size and shape, curing, and
concrete age. It was found that the sand type and f/c ratio influence the water demand of the
concrete mix. Sand type and f/c ratio also influence compressive strength, with higher
strength for a finer sand type and lower f/c ratios. However, the concrete density is the factor
that influences the strength the most.
3
Nguyen, Le Hung. "Béton de structure à propriétés d'isolation thermique améliorées : approche expérimentale et modélisation numérique." Phd thesis, Université de Cergy Pontoise, 2013. http://tel.archives-ouvertes.fr/tel-00931711.
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Dans un bâtiment, les déperditions thermiques proviennent de diverses parties opaques (mur, toit et plancher) qui peuvent contenir du béton. Il est donc intéressant d'envisager des formulations de béton de structure avec des propriétés d'isolation thermique améliorées. L'utilisation de granulats légers, qui possèdent de bonnes propriétés thermiques grâce à leur structure poreuse, peut être une solution pour améliorer la capacité d'isolation des éléments en béton. Cette technique d'isolation répartie peut permettre d'éviter des dispositifs constructifs lourds tout en répondant aux exigences de la RT 2012. La présente étude a pour objectif d'optimiser le couple performance mécanique - capacité isolante des bétons de granulats légers. Elle repose sur une double approche expérimentale et numérique.Les bétons de granulats légers ciblés ont une masse volumique inférieure à 1500 kg/m3 et une résistance en compression supérieure à 25 MPa. L'influence de la nature des granulats légers, du taux de substitution du sable alluvionnaire par du sable léger, du rapport E/C et de l'ajout de fumée de silice sur les performances mécaniques et thermiques des bétons est étudiée afin de proposer des formulations adéquates pour une large gamme d'usage structurel. Le module d'Young, la résistance en compression, la conductivité thermique et la diffusivité sont mesurées sur 25 formulations de bétons de granulats légers. Le comportement thermique de ces différents bétons en fonction de facteurs climatiques, comme la température et le degré d'humidité est aussi examiné afin d'optimiser leurs propriétés d'isolation thermique. L'ensemble des résultats expérimentaux permet une meilleure compréhension de la relation entre la formulation des bétons de granulats légers et leur rapport performance mécanique / pouvoir isolant. En s'appuyant sur certaines mesures expérimentales, des modélisations numériques reposant sur des techniques d'homogénéisation permettent d'identifier des propriétés thermiques (conductivité thermique, chaleur spécifique) et mécaniques (module d'Young, résistance à la rupture) des granulats légers (gravillons et sables) difficilement mesurables expérimentalement. Connaissant les propriétés thermiques et mécaniques des différents constituants, des modélisations prédictives des comportements macroscopiques des bétons légers sont développées à partir de schémas d'homogénéisation pour des matériaux multi-phases polydisperses. Les outils développés sont comparés et validés par confrontation aux mesures expérimentales pour les différentes familles de bétons de granulats légers étudiés. Ils permettront par la suite d'alléger les coûts et délais des campagnes expérimentales de mise au point des formulations. La modélisation, sur une année, des transferts thermiques à travers une enveloppe de bâtiment en béton de granulats légers permet de quantifier l'amélioration des performances thermiques des bétons de granulats légers par rapport à un béton classique.
4
Assunção, José Wilson. "Concreto Leve Autoadensável: avaliação da influência da argila expandida no processo de dosagem e nas propriedades do concreto." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/102/102131/tde-01072016-115653/.
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Esta tese aborda as influências do agregado leve na dosagem, características físicas e mecânicas de concreto autoadensável (CAA) quando na fração de graúdo da mistura, substitui-se parte do volume absoluto da brita de basalto (máx 19 mm) pelo volume equivalente de argila expandida brasileira (máx 12,7 mm). O fato de conhecer as implicações na reologia do CAA, provocadas pelo uso conjunto de agregados com características físicas distintas e, apresentar este tipo de concreto como uma alternativa promissora para uso na indústria da pré-fabricação em concreto, justificam esta pesquisa. A substituição da brita de basalto pela argila expandida (AE-1506), em teores de volume absoluto, foi de 20%, 40%, 60%, 80% e 100%. Como resultados, produziram-se concretos autoadensáveis com consumo de aglomerantes (cimento Portland CP V-ARI e sílica ativa) da ordem de 510 kg/m³, que atenderam aos limites de autoadensabilidade propostos pela norma NBR 15823-1 (2010). Na condição endurecida, apresentaram massa específica seca de 2.358,3 a 1.720,7 kg/m³, resistência à compressão (fc28) de 60 a 43 MPa, módulo de elasticidade (Esc) de 23 a 34 GPa e eficiência estrutural (FEE) de 22 a 29 MPa.dm³.kg-1, sem sinais visíveis de frente de carbonatação. Obteve-se concreto leve autoadensável (CLAA) a partir de misturas com fração de graúdo foi composta por 60% de argila expandida e 40% de brita de basalto, que atingiram massa específica seca de 1.986 kg/m³, resistência a compressão (fc28) de 51,3 MPa e condutividade térmica () de 1,07 a 1,53 W/m.K. Constatou-se que a argila expandida interfere significativamente nas características dos concretos exigindo, na comparação com CAA confeccionado com 100% de brita de basalto, maior teor de argamassa e relação volume de água/volume de finos mais elevado.<br>This thesis discusses aspects related to the influence of lightweight aggregate in the mix design, physical and mechanical properties of the self-compacting concrete (SCC) when replacing part of the absolute volume of basalt crushed stone (máx19 mm) with a lightweight aggregate equivalent absolute volume Brazilian expanded clay (máx 12,7 mm). Understanding interference on the rheology of the SCC caused by the use of aggregates with different physical properties and recommend this type of concrete as a promising alternative for the pre-fabricated concrete industry, justify this research. The replacement of basalt crushed stone for lightweight aggregate (AE-1506), in equivalent absolute volume, was 20%, 40%, 60%, 80% and 100%. As a result, self-compacting concrete was produced with consumption of binders (cement Portland CP V-ARI and silica fume) of about 510 kg / m³, appropriate for self- compactibility limits established by the ABNT NBR 15823-1 (2010) standard. In the hardened condition, the dry density value ranged from 2.358,3 to 1.720,7 kg/m³, compressive strength (fc28) ranged from 60 to 43 MPa, elasticity modulus (Esc) ranged from 23 to 34 GPa, and efficiency structural (FES) ranged from 22 to 29 MPa.dm³.kg-1, with no visible signs of carbonation. The self-compacting lightweight expanded clay concrete (SCLC) was obtained from mixtures which its absolute volume fraction of aggregate coarse was composed by 60% of expanded clay and 40% of basalt crushed stone, with dry density of 1986 kg/m³, compressive strength (fc28) of 51.3 MPa and thermal conductivity () varied from 1,07 to 1,53 W/m.K. It was found that the expanded clay significantly interferes in the properties of concretes demanding in comparison with SCC made with 100% basalt crushed stone, mortar content and ratio higher volume of water/volume of higher fines.
5
Arasteh, A. R. "Structural applications of lightweight aggregate foamed concrete." Thesis, University of Westminster, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382269.
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Aly, Atif M. A. H. "Effect of confinement on structural behaviour of axially loaded lightweight concrete columns." Thesis, University of Sheffield, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334784.
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Novotná, Aneta. "Možnosti využití rozptýlené výztuže pro lehké konstrukční betony." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226093.
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Master´s thesis deals with some problems associated with utilisation of lightweight concrete from the porous aggregates in the load – carrying structures. The thesis focuses on the possibilities of the increase of the cement composites toughness using dispersed reinforcement. Lightweight concretes were reinforced with a combination of different lengths of polypropylene fibers Forta Ferro. There were used polypropylene fibers of three lengths 19, 38, 54 mm. The thesis is divided into theoretical, experimental and static part.
8
Asik, Mesut. "Structural Lightweight Concrete With Natural Perlite Aggregate And Perlite Powder." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607728/index.pdf.
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Structural lightweight aggregate concrete is an important and versatile material,
which offers a range of technical, economic and environmental-enhancing and
preserving advantages and is designed to become a dominant material in the new
millennium. For structural application of lightweight concrete, the density is often
more important than the strength. A decreased density for the same strength level
reduces the self-weight, foundation size and construction costs. Structural
lightweight aggregate concrete generally used to reduce dead weight of structure as
well as to reduce the risk of earthquake damages to a structure because the
earthquake forces that will influence the civil engineering structures are proportional
to the mass of those structures.
In this study, structural lightweight aggregate concrete was designed with the use of
natural perlite aggregate that will provide an advantage of reducing dead weight of
structure and to obtain a more economical structural lightweight concrete by the use
of perlite powder as a replacement of the cement. Six mixes were produced with
different cement content and with or without perlite powder. Six mixes divided into
two groups according to their cement content. First group had a cement content of
300 kg/m3 and second group had cement content of 500 kg/m3<br>also the water/cement
ratios of groups were 0.49 and 0.35 respectively. Moreover, each group had three
sub-mixes with 0%, 20% and 35% of perlite powder as cement replacement.
According to results of experimental study, it was concluded that natural perlite
aggregate can be used in the production of structural lightweight aggregate concrete.
Based on the strength and density results of experimental work, it is possible to
produce lightweight concrete with 20 MPa-40 MPa cylindrical compressive strength
by using natural perlite aggregate. Also, the use of perlite powder, which will
provide economy, can reduce dead weight further and increase performance.
9
Cross, Benjamin Thomas. "Structural Performance of High Strength Lightweight Concrete Pretensioned Bridge Girders." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/26190.
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The use of high compressive strengths in prestressed bridge girders can lower costs by allowing for longer spans, increased girder spacing, and smaller cross-sections. If high strength lightweight concrete (HSLWC) is used, these advantages are further enhanced due to the corresponding reduction in self-weight. Additional benefits can then be realized in the form of more traffic lanes, increased load capacity, smaller substructures, reduced crane capacity requirements, and lower shipping costs.
Despite the possible economic savings, HSLWC has been used infrequently in prestressed bridge girder applications across the nation. While recent research has been performed to extend the applicability of current bridge design specifications to normal weight concretes with strengths as high as 18 ksi, little
has been done by comparison with regards to HSLWC. The purpose of the research in this report was to assess whether current bridge design specifications for transfer length, development length, prestress loss, camber, and flexural capacity are satisfactory for use with fully-bonded, pretensioned flexural members consisting of HSLWC and to make recommendations for improvements where necessary.
Twelve high strength pretensioned beams of variable unit weight (eight lightweight beams and
four normal weight beams) and strand size (eight beams with 0.5-in. strand and four beams with 0.6-in. strand) were cast at the Thomas M. Murray Structural Engineering Laboratory at Virginia Tech. These beams were allowed to sit for a period of several months after fabrication while measurements were taken regarding transfer length, prestress loss, and camber. After this period, the beams were load tested to collect development length data, flexural data, and further data related to prestress loss. In
addition to the laboratory cast beams, prestress loss and camber data from six full-size bridge beams (five lightweight beams and one normal weight beam) cast as part of a separate project at Virginia Tech was examined. Analysis of the results for all beams shows that with a few caveats, the current AASHTO LRFD Specifications and other design methods examined regarding the topics under consideration are satisfactory for use in the design of HSLWC pretensioned bridge girders with properties similar to those of the beams studied.<br>Ph. D.
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El, Zareef Mohamed [Verfasser]. "Conceptual and Structural Design of Buildings made of Lightweight and Infra-Lightweight Concrete / Mohamed El Zareef." Aachen : Shaker, 2010. http://d-nb.info/1120864259/34.
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Zareef, Mohamed el [Verfasser]. "Conceptual and Structural Design of Buildings made of Lightweight and Infra-Lightweight Concrete / Mohamed El Zareef." Aachen : Shaker, 2010. http://nbn-resolving.de/urn:nbn:de:101:1-201612041611.
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Wu, Lixian. "Engineering and durability properties of high performance structural lightweight aggregate concrete." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265612.
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Sampaio, Zodinio Laurisa Monteiro. "Low cement structural lightweight concrete with optimized multiple waste mix design." PROGRAMA DE P?S-GRADUA??O EM CI?NCIA E ENGENHARIA DE MATERIAIS, 2017. https://repositorio.ufrn.br/jspui/handle/123456789/24353.
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Previous issue date: 2017-04-25<br>The high-energy demand involved in the construction industry and the increasing consumption of concrete made this material an ideal option for the recycling of by-products from various industries such as: porcelain polishing residue (PPR); tire rubber residue (TRR) and limestone residue (LSR). These residues often lack a treatment that contributes to the degradation of the environment. In this sense, the use of by-products that increases the volume of the concrete without damaging significantly its properties, can be a viable option in the production of low-cost and sustainable low-weight concrete (LWC). The main objective of this work was to analyze the mechanical and thermal behavior of structural lightweight concrete (SLWC) with low cement consumption, produced with expanded clay (EC) in replacement of the aggregate and with the addition of PPR, TRR and LSR to replace the small aggregate. For this purpose, a 2? factorial design was used for the choice of SLWC with the best performance in terms of consistency, mechanical properties and density. Subsequently, reductions of 10, 20 and 30% of cement were performed on SLWC that presented better combination of properties and waste consumption and were characterized by mechanical tests. The best SLWC mix resulting from the combination of mechanical properties and cement consumption was characterized by permeability, flexural strength, TG/DTA, XRF, SEM, thermal capacity, thermal conductivity and thermal diffusivity. The results showed that residues contents around 21% presented better combination of properties. By maintaining the amount of residue at optimum levels it was possible to produce a SLWC with good rheological, mechanical and thermal properties with minimum cement consumption.<br>A alta demanda energ?tica envolvida na ind?stria da constru??o civil e o crescente consumo do concreto, fez com que o concreto se tornasse a op??o ideal para a reciclagem de subprodutos de v?rias industrias tais como: res?duo de polimento de porcelanato PPR; res?duo de borracha de pneu (TRR) e res?duo de pedra calc?ria (LSR). Esses res?duos frequentemente carecem de um tratamento adequando o que acaba contribuindo para a degrada??o do meio ambiente. Nesse sentido, o uso de subprodutos que ir?o aumentar o volume do concreto sem prejudicar muito as propriedades, pode ser uma op??o bastante vi?vel na produ??o de Concretos leves (CL) de baixo custo e sustent?veis. O objetivo geral desse trabalho foi analisar o comportamento mec?nico e t?rmico de concretos leves estruturais (CLE) de baixo teor de cimento produzidos com argila expandida (AE) em substitui??o ao agregado gra?do e com adi??o de PPR, TRR e LSR em substitui??o a parte do agregado mi?do. Para tal foi usado inicialmente um planejamento fatorial 2? para a escolha dos CLE com melhor desempenho em termos de consist?ncia, propriedades mec?nicas e massa espec?fica real. Posteriormente foram realizadas redu??es de 10, 20 e 30% de cimento nos CLE que apresentaram melhores desempenhos e caracterizados atrav?s de ensaios mec?nicos. O melhor tra?o resultante da combina??o de propriedades mec?nicas com o consumo de cimento foi caracterizado mediante ensaios de: permeabilidade; resist?ncia ? flex?o; TG/DTA; FRX; MEV; capacidade t?rmica; condutividade t?rmica e difusividade t?rmica. Por fim. Os resultados mostraram que teores de res?duos em torno de 21% apresentaram melhor combina??o de propriedades. Mantendo os teores de res?duos em n?veis ?timos foi poss?vel produzir um CLE com boas propriedades reol?gicas, mec?nicas e t?rmicas com um consumo m?nimo de cimento.
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Thomason, James Charles. "Development of high performance structural lightweight Portland cement concrete a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=0&did=2000396271&SrchMode=1&sid=2&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1277495413&clientId=28564.
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Saevarsdottir, Thorbjoerg. "The structural, serviceability and durability performance of variable density concrete panels." Thesis, University of Canterbury. Civil Engineering, 2008. http://hdl.handle.net/10092/1237.
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Conventional concrete is a poor insulating material but has good thermal mass, while lightweight concrete provides good insulation at the price of thermal mass. Precast concrete wall systems have not been widely used in residential homes due to poor thermal and acoustic performance, despite being high quality products that are easy to construct. The variable density concrete panel was designed to combine good thermal storage, insulation and high quality precast concrete. It is produced from a single concrete mix which is vibrated to get a lightweight top layer and a normal/heavyweight bottom layer. The lightweight layer is the wall exterior, having low thermal conductivity providing good thermal insulation while the normal/heavyweight layer is the dense wall interior, having high specific heat to provide good thermal mass and sufficient strength for construction handling and to withstand service loads. The intention of this research was to estimate the hardened performance; that is the structural, serviceability and durability performance of the variable density concrete panel. Further developments to the mix design were made where the fresh properties were measured and thermal performance estimated on hardened specimens. Most of the major technical concerns were proved not being as severe as first thought, making the production of variable density concrete panels promising. To ensure that the variable density concrete would stratify, the concrete mix had to have defined fresh properties. Defined rheological ranges gave a good indication of the stratification potential, but the degree of stratification was also found to be dependent on the intensity and time of vibration. Slump flow had to be within a certain range to achieve good stratification but this alone did not guarantee stratification. Variable density concrete was found to have adequate strength capacity both in axial compression and in tension for likely service loads but the strength required to withstand handling loads at early ages was not assessed. The strength of the variable density concrete was found to be affected by several factors such as; degree of stratification, relative strength and thickness of the layers, curing environment and amount of defects. As the stratification of the concrete increased the thermal insulation improved whereas the strength decreased. Warping was found not to significantly affect the serviceability of panels despite differential shrinkage within the element. The amount of warping was mainly related to the degree of stratification. Warping decreased with better stratification as more stress and strain was relieved in the lightweight layer. The lightweight concrete was significantly weaker as well as being less stiff than the structural concrete and therefore creeps to follow the structural concrete. The thermal properties aimed for were generally not reached, but these mixes were not designed to optimise the thermal performance and were tested before the concrete was fully dried. This increased thermal conductivity and therefore reduced the measured R-values. Stratified concrete had good absorption resistance, poor permeability properties and was highly porous. If the concrete was over-vibrated it tended to have a rough surface finish that would require a coating. Delamination of the panels was not assessed in this research but is a likely mode of failure.
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Dan-Jumbo, F. G. "Material and structural properties of a novel Aer-Tech material." Thesis, Coventry University, 2015. http://curve.coventry.ac.uk/open/items/699ca3a1-deec-4549-b907-0e06bcdad83f/1.
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This study critically investigates the material and structural behaviour of Aer-Tech material. Aer- Tech material is composed of 10% by volume of foam mechanically entrapped in a plastic mortar. The research study showed that the density of the material mix controls all other properties such as fresh state properties, mechanical properties, functional properties and acoustic properties. Appreciably, the research had confirmed that Aer-Tech material despite being classified as a light weight material had given high compressive strength of about 33.91N/mm2. The compressive strength characteristics of Aer-Tech material make the material a potential cost effective construction material, comparable to conventional concrete. The material also showed through this study that it is a structural effective material with its singly reinforced beam giving ultimate moment of about 38.7KN. In addition, the Aer-Tech material is seen as a very good ductile material since, the singly reinforced beam in tension showed visible signs of diagonal vertical cracks long before impending rapture. Consequently, the SEM test and the neural network model predictions, carried out had showed how billions of closely tight air cells are evenly distributed within the Aer-Tech void system as well as the close prediction of NN model for compressive strength and density are same with the experimental results of compressive strength and density. The result shows that the Aer-Tech NN-model can simulate inputs data and predicts their corresponding output data.
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Maheswaran, S. "The effect of creep and shrinkage on lightweight reinforced concrete slabs restrained by steel edge beams." Thesis, University of Hertfordshire, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373777.
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Inwood, Michael. "Review of the New Zealand Standard for Concrete Structures (NZS 3101) for High Strength and Lightweight Concrete Exposed to Fire." University of Canterbury. Civil Engineering, 1999. http://hdl.handle.net/10092/8276.
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This report describes the thermal properties, strength, and elastic modulus of lightweight, normal, and high strength concrete at elevated temperatures.
Section 6 (Design for Fire Resistance) of the New Zealand standard for concrete structure (NZS3101, 1995) provides recommended values and minimum requirements for concrete at elevated temperatures. These values will be reviewed with respect to overseas standards and experimental data to find their applicability to lightweight and high strength concretes.
A series of tests were performed on 1m x 1m lightweight and high strength concrete specimens to determine their insulation fire resistance. The specimens were produced in three thicknesses; 60, 130, and 175mm. This follows the method of earlier tests by Wade et al. (1991) and Wade (1992) on New Zealand aggregate concretes.
It was determined that the strength reduction curve given by NZS3101 over-predicts the strength of high strength concrete at elevated temperatures, though the values for elastic modulus and insulation fire resistance can be applied to high strength concrete.
The insulation fire resistance, strength, and elastic modulus values given by NZS3101 were found to also apply to lightweight concrete.
The report recommends a change to the elastic modulus curve given in NZS3101. The purpose of this is to give consistency between the strength and elastic modulus curves, which do not currently reach zero at the same temperature.
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Borja, Edilberto Vitorino de. "Efeito da adi??o de argila expandida e adi??es minerais na formula??o de concretos estruturais leves autoadens?veis." Universidade Federal do Rio Grande do Norte, 2011. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15567.
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Previous issue date: 2011-02-10<br>The search for alternative materials with lower density, reduction in heat transfer and
propagation of noise associated with the ease of handling and application in concrete
structures, represents an enormous challenge in the formulation and knowledge of
the performance of self-compacting lightweight concrete, which has technology little
known nationally, and appears on the international scene as an innovative material
and alternative to conventional concrete. Based on these, this study set out to study
self-compacting lightweight concrete made with two distinct grades of expanded clay
associated with the addition of plasticizing/superplasticizers additives and mineral
additions of metakaolin and bagasse ash of sugar cane. There is also an object of
study, evaluation of pozzolanic activity of mineral admixtures and their influence on
the durability characteristics of concrete. The rheological, physical, mechanical and
microstructural analysis in this study served as basis in the classification of concretes
autoadens?veis, targeting the national technical requirements for their classification
in the category autoadens?vel and lightweight structural. The inclusion of mineral
admixtures (metakaolin and bagasse ash of sugar cane), partial replacement of
cement, pozzolanic activity and demonstrated maintenance of mechanical properties
through the filler effect, a reduction of up to 76% of the nitrogen gas permeability in
blend with 20% bagasse ash. All concretes had rheology (cohesion and consistency)
suitable for self-adensability as well as strength and density inherent structural
lightweight concrete without presenting phenomena of segregation and exudation<br>A busca por materiais alternativos de menor massa espec?fica, redu??o na
transfer?ncia de calor e propaga??o do barulho, associado ? facilidade de manuseio
e aplica??o em estruturas de concreto armado, representa grande desafio na
formula??o e conhecimento do desempenho de concretos estruturais leves
autoadens?veis, que tem tecnologia pouco difundida em n?vel nacional, e surge no
cen?rio internacional como um material inovador e alternativo ao concreto
convencional. Frente ao exposto, este trabalho se prop?s a estudar concretos
estruturais leves autoadens?veis elaborados com duas gradua??es distintas de
argila expandida associados ? inclus?o de aditivos plastificantes/superplastificantes
e adi??es minerais de metacaulim e cinza de biomassa de cana-de-a??car. Tem-se
ainda como objeto do estudo, a avalia??o da atividade pozol?nica das adi??es
minerais e sua influ?ncia nas caracter?sticas de durabilidade dos concretos. As
propriedades reol?gicas, f?sicas, mec?nicas e microestruturais, analisadas neste
estudo, serviram como fundamenta??o na qualifica??o dos concretos leves
autoadens?veis, visando ?s exig?ncias t?cnicas nacionais para sua classifica??o no
quesito autoadens?vel e estrutural leve. A inclus?o das adi??es minerais
(metacaulim e cinza de biomassa de cana-de-a??car), em substitui??o parcial do
cimento, demonstrou atividade pozol?nica e manuten??o das propriedades
mec?nicas atrav?s do efeito filler, apresentando redu??o de at? 76% da
permeabilidade a g?s nitrog?nio na mistura com 20% de cinza de biomassa. Todos
os concretos dosados apresentaram reologia (coes?o e consist?ncia) adequada
para autoadensabilidade, bem como resist?ncia e massa espec?fica inerentes aos
concretos estruturais leves, sem apresentar fen?menos de segrega??o e exsuda??o
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Mamede, Fabiana Cristina. "Utilização de pré-moldados em edifícios de alvenaria estrutural." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-06062006-162432/.
Full textAbstract:
Elementos pré-moldados são uma opção para aumentar a racionalização no processo construtivo em alvenaria estrutural. Eles associam-se a particularidades desse processo com relação à rapidez de execução, rígido controle de qualidade, coordenação modular e alto nível organizacional da produção. Este trabalho pesquisou os pré-moldados freqüentemente utilizados em edifícios de alvenaria estrutural, tais como: blocos, escadas, contramarcos, vergas e peças de ajuste dimensional. Os pré-moldados foram analisados em seus aspectos estruturais, dimensionais e geométricos, respeitando-se as características que os tornam viáveis no aspecto construtivo, como a facilidade de produção, de manuseio e de transporte. Considerou-se, sempre, a coordenação modular e a compatibilização dimensional entre os componentes e subsistemas. Quando necessário, foram apresentados roteiro e exemplo de projeto, assim como quadros comparativos de vantagens e desvantagens<br>Precast concrete elements are a good option to improving the rationalization in structural masonry building process. They are related to the following features of this process: reduction of building times consumption, strict quality control, modular coordination and high level of manufacturing organization. This work deals with precast concrete elements commonly used in structural masonry buildings, such as: blocks, stairs, windows frames, lintels and pieces for dimensional adjustment. Structural, dimensional and geometrical characteristcs of precast concrete elements are analysed, considering the viability of production, transporting and handling the pieces. Modular coordination and the dimensional compatibility are always taken in account. Guidelines, design examples and comparative tables with pros and cons are inserted when convenient
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Olejníček, Pavel. "Strojírenská hala." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-410069.
Full textAbstract:
The diploma thesis deals with a new building of a single-storey production object, which is made as a precast concrete frame with a lightweight cladding. Part of the new building is also facilities for employees and its administrative staff, which is also based on precast concrete frame divided into two floors. Cladding is made as masonry with ventilated facade. The internal division of buildings is made by plasterboard partitions. The project is located in the industrial zone Košíkov near Velká Bíteš.
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Gelbrich, Sandra. "Funktionsintegrative Leichtbaustrukturen für Tragwerke im Bauwesen." Doctoral thesis, Universitätsbibliothek Chemnitz, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-215103.
Full textAbstract:
In den letzten Jahren gewinnt der Leichtbau im Bauwesen im Zuge der Ressourceneinsparung wieder stärker an Bedeutung, denn ohne eine deutliche Steigerung der Effizienz ist zukunfts-fähiges Bauen und Wohnen nur schwer zu bewerkstelligen. Optimiertes Bauen, im Sinne der Errichtung und Unterhaltung von Bauwerken mit geringem Einsatz an Material, Energie und Fläche über den gesamten Lebenszyklus eines Gebäudes hinweg, bedarf des Leichtbaus in punkto Material, Struktur und Technologie. In der vorliegenden Arbeit wird ein wissenschaftlicher Überblick zum aktuellen Stand der eigenen Forschungen in Bezug auf funktionsintegrativen Leichtbau im Bauwesen gegeben sowie erweiterte Methoden und Ansätze abgeleitet, die eine Konzeption, Bemessung und Erprobung von neuartigen Hochleistungs-Tragstrukturen in Leichtbauweise gestatten. Dabei steht die Entwicklung leistungs-starker und zugleich multifunktionaler Werkstoffkombinatio-nen und belastungsgerecht dimensionierter Strukturkomponenten unter dem Aspekt der Gewichtsminimalität in Material und Konstruktion im Fokus. Ein breit gefächertes Eigen-schaftsprofil für \"maßgeschneiderte\" Leichtbauanwendungen besitzen textilverstärkte Ver-bundbauteile, denn sowohl die Fadenarchitektur als auch die Matrix können in weiten Berei-chen variiert und an die im Bauwesen vorliegenden komplexen Anforderungen angepasst werden. In der vorliegenden Arbeit werden hierzu vor allem Methoden und Lösungen anhand von Beispielen zu: multifunktionalen Faser-Kunststoff-Verbunden (FKV), funktionsintegrier-ten faserverstärkten mineralischen Tragelemente und Verbundstrukturen in textilbewehrter Beton-GFK-Hybridbauweise betrachtet. Von zentraler Bedeutung ist dabei die Schaffung von materialtechnischen, konstruktiven und technologischen Grundlagen entlang der gesamten Wertschöpfungskette – von der Leichtbauidee über Demonstrator und Referenzobjekt bis hin zur technologischen Umsetzung zur Überführung der Forschungsergebnisse in die Praxis<br>In the last few years, lightweight construction in the building sector has gained more and more importance in the course of resource saving. Without a significant increase in efficiency, future-oriented construction and resource-conserving living is difficult to achieve. Optimized building, in the sense of the erection and maintenance of buildings with little use of material, energy and surface over the entire life time cycle of a building, requires lightweight design in terms of material, structure and technology. In this thesis, a scientific overview of the current state of research on function-integrative light-weight construction in architecture is presented. Furthermore, advanced methods and research approaches were developed and applied, that allows the design, dimensioning and testing of novel high-performance supporting structures in lightweight design. The focus is on the development of high-performance, multi-functional material combinations and load-adapted structural elements, under the aspect of weight minimization in material and construction. Textile-reinforced composites have a broad range of material properties for optimized \"tailor-made\" lightweight design applications, since the thread architecture as well as the matrix can be varied within wide ranges and can adapted to the complex requirements in the building industry. Within the scope of this thesis, methods and solutions are examined in the field of: multifunc-tional fiber-reinforced plastics (FRP), function-integrated fiber-reinforced composites with mineral matrix (TRC) and textile-reinforced hybrid composites (BetoTexG: combination of TRC and FRP). In this connection the creation of material, structural and technological foundations along the entire value chain is of central importance: From the lightweight design idea to the demonstrator and reference object, to the technological implementation for the transfer of the research results into practice
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Reto, Saba Alexandra Melissa, and Carbajal Renzo Saúl Sanabria. "Propuesta de uso de concreto liviano estructural con Perlita de Poliestireno Expandido (PPE) para mejorar la respuesta sísmica de un sistema de albañilería confinada en Lima, Perú." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2021. http://hdl.handle.net/10757/656494.
Full textAbstract:
Hoy en día existen diversas estructuras en la que se ha dado la aplicación del concreto liviano estructural, por lo que empresas contratistas apuestan por agregados livianos para fabricar concreto liviano de alta resistencia y que cumpla con sus requisitos de diseño. Estos estudios comenzaron a principios de la década de 1980, con óptimos resultados en 1992. Como resultado de todos estos aportes, la información de diseño se ha convertido al alcance de muchos profesionales, y ha permitido que el concreto liviano sea utilizado en alta resistencia y alta durabilidad (Hoff 1992). Es por ello mismo, que nuestra investigación propone el uso de un concreto liviano estructural con perlita de poliestireno expandido en un sistema de albañilería confinada.
Este estudio comprende la elaboración del diseño de un concreto liviano estructural; en primer lugar, se investigó un rango apropiado de perlita ya que según Thanon y Jihad (2016) señalan que para obtener óptimos resultados en resistencia a compresión la dosificación de perlita debe variar entre un intervalo de 13-23% ,y es por ello mismo que se escoge trabajar con un porcentaje de 16 % de perlita de poliestireno expandido, pero para términos de comprobación en las propiedades térmicas, también se diseñó con 26% y 36% de perlita; en segundo lugar, para proceder a realizar el diseño del concreto se diseña en base a los requisitos mínimos que establece ACI 318 y con referencias en ACI 211R, la cual interviene en ciertos parámetros para obtener las características de un concreto liviano estructural.<br>Today there are various structures in which there has been the application of lightweight structural concrete, so contractor companies are committed to lightweight aggregates to manufacture lightweight, high strength concrete that meets its design requirements. These studies conducted in the early 1980s, with optimal results in 1992. As a result of all these contributions, design information has become available to many professionals, and has allowed light concrete to be used for new applications and novelties where high strength and high durability are desirable (Hoff 1992). That is why our research proposes the use of a lightweight structural concrete with expanded polystyrene bead in a confined masonry system for single-family homes.
This study includes the development of the design of a lightweight structural concrete; First, a range of bead was investigated since according to Thanon and Jihad (2016) it was pointed out that to obtain optimum results in compressive strength the dosage of perlite must vary between a range of 13-23%, and that is why same that it is chosen to work with a percentage of 16% expanded polystyrene perlite, but for terms of checking the thermal properties, it is also designed with 26% and 36% perlite; secondly, to proceed with the design of the concrete, it is designed based on the minimum requirements established by ACI 318 and with references in ACI 211R, the quality of intervention in specific parameters to obtain the characteristics of a lightweight structural concrete.<br>Tesis
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Gelbrich, Sandra. "Funktionsintegrative Leichtbaustrukturen für Tragwerke im Bauwesen." Doctoral thesis, Universitätsverlag der Technischen Universität Chemnitz, 2016. https://monarch.qucosa.de/id/qucosa%3A20605.
Full textAbstract:
In den letzten Jahren gewinnt der Leichtbau im Bauwesen im Zuge der Ressourceneinsparung wieder stärker an Bedeutung, denn ohne eine deutliche Steigerung der Effizienz ist zukunfts-fähiges Bauen und Wohnen nur schwer zu bewerkstelligen. Optimiertes Bauen, im Sinne der Errichtung und Unterhaltung von Bauwerken mit geringem Einsatz an Material, Energie und Fläche über den gesamten Lebenszyklus eines Gebäudes hinweg, bedarf des Leichtbaus in punkto Material, Struktur und Technologie.
In der vorliegenden Arbeit wird ein wissenschaftlicher Überblick zum aktuellen Stand der eigenen Forschungen in Bezug auf funktionsintegrativen Leichtbau im Bauwesen gegeben sowie erweiterte Methoden und Ansätze abgeleitet, die eine Konzeption, Bemessung und Erprobung von neuartigen Hochleistungs-Tragstrukturen in Leichtbauweise gestatten. Dabei steht die Entwicklung leistungs-starker und zugleich multifunktionaler Werkstoffkombinatio-nen und belastungsgerecht dimensionierter Strukturkomponenten unter dem Aspekt der Gewichtsminimalität in Material und Konstruktion im Fokus. Ein breit gefächertes Eigen-schaftsprofil für \"maßgeschneiderte\" Leichtbauanwendungen besitzen textilverstärkte Ver-bundbauteile, denn sowohl die Fadenarchitektur als auch die Matrix können in weiten Berei-chen variiert und an die im Bauwesen vorliegenden komplexen Anforderungen angepasst werden. In der vorliegenden Arbeit werden hierzu vor allem Methoden und Lösungen anhand von Beispielen zu: multifunktionalen Faser-Kunststoff-Verbunden (FKV), funktionsintegrier-ten faserverstärkten mineralischen Tragelemente und Verbundstrukturen in textilbewehrter Beton-GFK-Hybridbauweise betrachtet. Von zentraler Bedeutung ist dabei die Schaffung von materialtechnischen, konstruktiven und technologischen Grundlagen entlang der gesamten Wertschöpfungskette – von der Leichtbauidee über Demonstrator und Referenzobjekt bis hin zur technologischen Umsetzung zur Überführung der Forschungsergebnisse in die Praxis.<br>In the last few years, lightweight construction in the building sector has gained more and more importance in the course of resource saving. Without a significant increase in efficiency, future-oriented construction and resource-conserving living is difficult to achieve. Optimized building, in the sense of the erection and maintenance of buildings with little use of material, energy and surface over the entire life time cycle of a building, requires lightweight design in terms of material, structure and technology.
In this thesis, a scientific overview of the current state of research on function-integrative light-weight construction in architecture is presented. Furthermore, advanced methods and research approaches were developed and applied, that allows the design, dimensioning and testing of novel high-performance supporting structures in lightweight design. The focus is on the development of high-performance, multi-functional material combinations and load-adapted structural elements, under the aspect of weight minimization in material and construction. Textile-reinforced composites have a broad range of material properties for optimized \"tailor-made\" lightweight design applications, since the thread architecture as well as the matrix can be varied within wide ranges and can adapted to the complex requirements in the building industry.
Within the scope of this thesis, methods and solutions are examined in the field of: multifunc-tional fiber-reinforced plastics (FRP), function-integrated fiber-reinforced composites with mineral matrix (TRC) and textile-reinforced hybrid composites (BetoTexG: combination of TRC and FRP). In this connection the creation of material, structural and technological foundations along the entire value chain is of central importance: From the lightweight design idea to the demonstrator and reference object, to the technological implementation for the transfer of the research results into practice.
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Tajra, Feras [Verfasser], Dietmar [Akademischer Betreuer] Stephan, Dietmar [Gutachter] Stephan, Frank U. [Gutachter] Vogdt, and Karl-Christian [Gutachter] Thienel. "Study on the production of core-shell structured lightweight aggregate by cold-bonding agglomeration process and its utilization in concrete / Feras Tajra ; Gutachter: Dietmar Stephan, Frank U. Vogdt, Karl-Christian Thienel ; Betreuer: Dietmar Stephan." Berlin : Technische Universität Berlin, 2020. http://d-nb.info/1206245581/34.
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Kasza, Radomír. "Stavebně technologický projekt Pavilonu farmacie na VFU v Brně." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-227057.
Full textAbstract:
This master´s thesis solves the construction technological project of Pharmacy Pavilon II at the Veterinary University in Brno. It consists of parts of the project site equipment, technical reports, schedule of the main building, the control and test plan, design, an inventory of machines, financial plan of organization development, a register of environmental aspects, technological regulations and the plan for securing material resources.
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Lia, Dirk, and 賴坤毅. "Economy Assessment for Steel-structure Buildings Using Lightweight Aggregate Concrete." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/11358399014807486730.
Full textAbstract:
碩士<br>國立中興大學<br>土木工程學系<br>91<br>There is no previous case in lightweight aggregate burned from reservoir sediment all over the world. But in Taiwan one factory has successfully developed this technology recently. This technology can change the sediment into resource. The purpose of this project is to assess the economy of the steel structure built using the lightweight aggregate concrete (LWAC). The assessment is aimed at one aspect which is the construction cost. In the aspect of construction cost, three simulated buildings of 7, 20 and 60 floors were analyzed and one real building of 26 floors was used to verify the analysis. The analyzed results in the aspect of construction cost indicate that although the cost of the LWAC is 50% higher than NWAC, the high-rise building made by LWAC can be cheaper than that made by NWAC after some turning-point floor. But the turning points will be influenced by the total dead load. In the structure system used in this project, the turning point will be at 42nd floor if the total dead load is 370kg/cm2, 26th floor if the total dead load is 700kg/cm2 and 13th floor if the total dead load is 1000kg/cm2. In addition, the analyzed results also show that the turning point will be affected by different structure systems.
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Tsyr, Wang Shin, and 王心慈. "Seismic Design and Economics of Lightweight Aggregate Concrete in Building and Bridge Structure." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/43756360855373328158.
Full textAbstract:
碩士<br>國立臺灣科技大學<br>營建工程技術學系<br>81<br>Lightweight concrete has been used for many years in the main
structures of buildings and bridges in many developed
countries but not in Taiwan. Due to the ability of reducing
the earthquke forces and the shortage of natural aggregates
in Taiwan, the lightweight concrete has held public attention
on its development . Since the previous studies had
reported the manufacture, mechancial proporties and member
performance of the lightweight concrete, this study is
focussing on the practical difference between the
lightweight and the normalweight concrete and the economic
utility. The study includes two categories - bridges and
highrise buildings for both the normal and lightweight
concrete. Through the dynamic analysis and seismic design, it
is found in the light weight concrete bridge that the more
economy is gained for the case of the longer span and the
greater ratio of dead load. It is also found that the
lightweight concrete bridge deck with steel girder is most
promising for the reason of economy. In highrise building, a
22 floors reinforced concrete buildings was studied. If the
whole structure is degigned with the lightweight concrete, the
design earthquake force could be reduced about 19%, and the
quantity of reinforcements could be reduced 15%. The
greater economic utility could be achieve if the unit price
of light weight material is lower than twice of the
natural normal material.
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Piyamaikongdech, Ake. "Ductile lightweight concrete for lightweight structural application." 2007. http://hdl.handle.net/10106/908.
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Tanner, Jennifer Elaine. "Design provisions for autoclaved aerated concrete (AAC) structural systems." 2003. http://wwwlib.umi.com/cr/utexas/fullcit?p3116203.
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Li, Tai-Wei, and 李岱蔚. "Comparison of the performance of bridge structures constructed by lightweight concrete and normal-weight concrete." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/91048526390359525479.
Full textAbstract:
碩士<br>國立中興大學<br>土木工程學系所<br>102<br>The primary goal of this study is to research when the bridge foundations subject vertical vibration, the account settlement of bridge structures and when the bridge subject?seismic excitation, comparison of the lateral force and acceleration by lightweight concrete and normal-weight concrete. Bridge structures analysis use the two-degree-of freedom system with an equivalent stiffness and damping ratio. The settlement on the bridge is produced by the vertical vibration. The vertical vibration consider the sources include generate vibrations in nearby structures and vibration caused by train. In cases the vibration produce bridge settlement was very low. The lateral force on the bridge is produced by the seismic excitation. The analysis method is used response spectrum and time history. In cases the seismic excitation produce bridge lateral force and acceleration on the lightweight concrete bridge is not sure more than normal-weight concrete bridge.Keywords：soil-pile interaction；settlement；lightweight concrete
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wei, wu jiun, and 吳雋瑋. "An Experimental Study on the Mixed Proportion Design of Lightweight Structural Concrete." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/24235048263989201475.
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碩士<br>中華大學<br>營建管理研究所<br>95<br>The sludge causes the water pollution and storage reduction of a reservoir, threatening its functionality and operational life span. Also, due to the fact that sand is heavily used in construction, its supply is diminishing. Thus, it might be a good idea to make sludge into lightweight aggregate. This new concept will not only recycle the sludge but also make it one of the valuable natural resources. Furthermore, it can increase the water storage capacity of a reservoir and expand the sources of construction aggregate materials.
In Taiwan, the production and application of lightweight aggregate is still in the initial stage. Ensuring the stability in quality and reducing cost by quality controlled formulas is an essential issue for the lightweight aggregate industry.
The research first select, from literature reviews as well as past experimental results, some factors which are influential to lightweight concrete for structural applications, including water content, water-binder ratio (W/B), and unit weight of lightweight aggregate. Then, by using Design Of Experiment (DOE) and Analysis of Variance (ANOVA), the research discusses the degree which those controlled factors and their interaction would influence quality characteristics, such as compressive strength, ultrasonic wave, and electric resistance, at different ages and whether they satisfy the requirements of ACI Code.
Considering the average and variance, the research finds the optimal mixed proportion design by combining ages and quality characteristics by using Type III Signal to Noise Ratio of Taguchi Method. The obtained results are: unit weight of lightweight aggregate at 0.378g/cm3; water consumption at 160kg/m3; water-binder ratio at 0.28.
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Zareef, Mohamed el [Verfasser]. "Conceptual and structural design of buildings made of lightweight and infra-lightweight concrete / vorgelegt von Mohamed Ahmed Mohamed El Zareef." 2010. http://d-nb.info/100391991X/34.
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Marques, Paula Cristina Martins Pina. "Design of fibrous structures for civil engineering applications." Master's thesis, 2009. http://hdl.handle.net/1822/9743.
Full textAbstract:
Dissertação de mestrado em Design e Marketing<br>Os recentes desenvolvimentos, ocorridos na tecnologia das fibras e nas estruturas
fibrosas, permitiram produzir materiais fibrosos avançados para inúmeras aplicações
não convencionais. O uso de materiais fibrosos como material de reforço de matrizes
cimentícias é uma das aplicações que na última década tem sofrido vários
desenvolvimentos. Devido à ausência de uma adequada resistência à tracção, os
elementos de betão necessitam de reforço, de forma a maximizar a sua capacidade de
fazer face às solicitações mecânicas. Um dos materiais mais utilizados para reforço do
betão, é o aço, sendo por isso actualmente o mais aceite como forma de reforço. No
entanto, devido à corrosão, fadiga e aos efeitos nefastos da presença de agentes
agressivos, a rotura das estruturas de betão reforçadas com aço, é uma consequência
inevitável. De forma a ultrapassar os problemas associados às estruturas de betão
reforçadas com aço, nomeadamente o da corrosão, e simultaneamente melhorar e
aumentar o tempo de vida útil das estruturas e a sua durabilidade, uma nova
abordagem ao reforço do betão tem sido alvo de desenvolvimentos – Textile
Reinforced Concrete (TRC) – betão reforçado com estruturas fibrosas. Assim, o TRC é
um material de construção inovador no qual os materiais fibrosos são utilizados para
reforçar matrizes cimentícias de forma a eliminar o problema da corrosão do aço e a
fornecer a resistência à tracção adequada ao elemento de betão.
Neste contexto o principal objectivo deste trabalho é o desenvolvimento de estruturas
fibrosas, nomeadamente estruturas fibrosas orientadas direccionalmente (EFOD) para
aplicações na construção civil enquanto material de reforço de elementos leves de
betão, substituindo o aço e ultrapassando a sua principal desvantagem – a corrosão.
Foram desenvolvidas dez estruturas EFOD variando o reforço no sentido transversal e
longitudinal. Lajes de betão auto-compactável foram reforçadas com as EFOD e
ensaios de flexão foram realizados de forma a avaliar o seu desempenho mecânico e
identificar a influência da massa linear (tex) e densidade estrutural dos reforços
(mechas de fibras/cm) em estruturas abertas 0/900. O comportamento mecânico das
lajes reforçadas com as estruturas fibrosas foi comparado com o comportamento
mecânico de lajes reforçadas com aço e com lajes sem reforço. Os resultados indicam
que as EFOD melhoram o comportamento mecânico do betão à flexão. A massa linear
e a densidade estrutural das mechas mostram ter uma influência significativa no
comportamento mecânico do betão tendo sido possível estabelecer correlações
interessantes entre estes factores e o desempenho mecânico no que se refere à
absorção de energia em ensaio de flexão.<br>As a synergy of fibre and fibrous structures technology developments, nowadays it is
possible to produce advanced fibrous materials for many non-conventional
applications. The use of fibrous materials as reinforcement materials of cementitious
matrices is one of its many applications that have gain new developments over the last
years. Due to its inherent low tensile strength, concrete requires reinforcement in
applications where significant tensile stresses will be realized in order to maximize its
load-carrying capability. Currently the most widely accepted form of reinforcement is
welded-wire mesh (WWM) of steel. However, due to steel corrosion, fatigue and other
degradation agents, failure of those reinforced concrete structures is an unavoidable
consequence. Thus, the development of alternative materials to steel in concrete
reinforcement has been a priority in the last decades. In order to overcome the
problems associated to the steel reinforced concrete, namely corrosion and
simultaneously improve the serviceability and performance durability of steel
reinforced concrete structures a new approach to concrete reinforcement has been
developed in the last years - Textile Reinforced Concrete (TRC). Thus, TRC is an
innovative construction material where fibrous structures are used to reinforce
cementitious matrices in order to eliminate the corrosion of steel reinforcement,
providing adequate tensile strength to the concrete reinforced element.
In this context the main objective of the present work consisted in the development of
fibrous structures, namely directionally oriented fibrous structures (DOFS) for civil
construction as reinforcement material for lightweight concrete elements, replacing
steel and overcoming it main drawback – corrosion. It was developed and produced
ten different DOFS varying the transversal and longitudinal reinforcement. Selfcompacting
concrete slabs were reinforced with the DOFS and bending tests were
carried out in order to evaluate their mechanical behaviour and identify the influence
of linear density (tex) and structural density of the reinforcements (rovings/cm) in
open 0/900 structures. The mechanical behaviour of the reinforced concrete slabs
were compared to that mechanical behaviour of steel reinforced concrete and also
with slabs without any reinforcement. The results show that DOFS improve the
bending mechanical behaviour. Either linear density or roving structural density has
shown to have a significant influence on the reinforced concrete element energy
absorption capacity in a different way and depending on the percentage of fibre.
Correlations between these tow factors and energy absorption under bending test have been established.
35
Torre, Véronique da Silva Ramos da. "Avaliação experimental da utilização de conectores indentados em elementos mistos de aço e betão leve." Master's thesis, 2015. http://hdl.handle.net/1822/40622.
Full textAbstract:
Dissertação de mestrado integrado em Engenharia Civil<br>Este trabalho procura avaliar o comportamento de conectores do tipo Crestbond quando
inseridos em lajes maciças de betão leve. O conector Crestbond possui saliências e
reentrâncias trapezoidais que proporcionam resistência ao corte longitudinal e previnem
a separação transversal entre o perfil metálico e a laje de betão (efeito uplift).
O estudo realizado é de índole essencialmente experimental. Para tal, são realizados
ensaios de tipo push-out, conforme os procedimentos descritos na norma (NP EN 1994-
1-1) e a montagem já utilizada em ensaios anteriormente realizados na Universidade do
Minho. Apresenta-se e discutem-se os resultados obtidos nos ensaios realizados.
Neste projeto utilizam-se dois tipos de betão. A composição dos betões difere
essencialmente no tipo de argila expandida utilizada, tendo-se escolhido a Leca M e a
Leca HD. Como resultado, obteve-se um betão leve com fcm aproximadamente igual a
15 MPa e um outro betão leve com fcm de aproximadamente 30 MPa.
No total, foram ensaiados 6 provetes, 4 deles com um betão de resistência à compressão
fcm = 30 MPa onde se utilizou argila expandida do tipo Leca HD e armaduras com
diâmetros de 6 e de 10 mm. Os restantes 2 provetes foram realizados com um betão leve
de resistência à compressão fcm = 15 MPa, onde se utilizou uma mistura de argila
expandida dos tipos Leca M e Leca HD e armadura com diâmetro de 6 e de 10 mm.
Nos ensaios realizados, avalia-se o comportamento da conexão, a sua capacidade de
carga , a sua ductilidade e os modos de rutura associados.
Os resultados obtidos são comparados com outros resultados obtidos anteriormente com
betão de massa volúmica normal.<br>This study evaluates the behavior of the Crestbond connector when inserted into
lightweight concrete (LWC) solid slabs. The Crestbond connector presents a trapezoidal
indented shape that provides resistance to slip and prevents the uplift effect between the
steel profile and the concrete slab.
The work conducted is essentially experimental. Push-out tests are carried out according
to the procedures described in the standard NP EN 1994-1-1 and the setup already used
in tests previously carried out at the University of Minho. The results obtained in the
tests are presented and discussed.
The specimens tested are fabricated with two types of lightweight concrete. The
concrete mixtures differ essentially on the type of expanded clay used, having been
chosen the Leca M and Leca HD. As a result, there was obtained a lightweight concrete
with compressive strength fcm approximately equal to 15 MPa (Type 1) and another
lightweight concrete with compressive strength fcm of about 30 MPa (Type 2).
A total of 6 samples were tested, two of them with LWC of Type 1 (fcm = 15 MPa) in
which a mixture of expanded clay of types Leca HD and Leca M was used and
reinforcement bars with diameters of 6 and 10 mm. The other four specimens were
fabricated with LWC of Type 2 (fcm = 30 MPa), produced with expanded clay of type
Leca HD and reinforcement bars with a diameters of 6 and 10 mm.
The push-out tests were performed in order to evaluate the connection behavior, its load
carrying capacity, the ductility and the associated failure modes.
The results obtained in the tests are compared with other results previously obtained in
push-out tests performed in specimens with normal density concrete.