Dissertations / Theses on the topic 'Modified concrete'
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1
Gowripalan, N. "Reinforcement of concrete elements with modified polymers." Thesis, University of Leeds, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378032.
2
Konduru, Sathish Kumar Raju. "Performance evaluations of latex-modified and silica fume modified concrete overlays for bridge decks." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10559.
Abstract:
Thesis (M.S.)--West Virginia University, 2009.Title from document title page. Document formatted into pages; contains xv, 235 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 212-216).
3
Watson, David William. "Monitoring moisture movement within modified concretes." Thesis, Heriot-Watt University, 1997. http://hdl.handle.net/10399/641.
4
Oommen, Dony Cherian. "Carbon fiber reinforced latex modified concrete for bridge deck overlays." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4760.
Abstract:
Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains x, 103 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 84-87).
5
Buchanan, Patricia Michelle. "Shrinkage of Latex-Modified and Microsilica Concrete Overlay Mixtures." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/33102.
Abstract:
Highway bridge decks are often overlaid to extend service life by reducing the rate of chloride ion ingress and the rate of corrosion of reinforcing steel in the sound chloride-contaminated concrete that is left in-place. Bridge deck overlays in Virginia are usually either latex-modified concrete or microsilica concrete, and both types of overlay are considered equivalent in terms of performance. However, the latex-modified concrete overlays are more expensive to construct than the microsilica concrete overlays. Thus, it is important to determine if these overlays do perform equivalently to ensure that short-term savings do not lead to higher long-term costs.
Shrinkage is one of the overlay performance parameters. Shrinkage is a three-dimensional deformation of concrete that results in an overall reduction in volume. Total shrinkage may be measured under either restrained or unrestrained conditions.
This research examines the shrinkage performances of Virginia Department of Transportation-approved latex-modified and microsilica concrete overlay mixtures and was conducted on both field-sampled and laboratory-fabricated restrained and unrestrained specimens. Based on crack and delamination surveys of sampled bridge decks and laboratory test results, a shrinkage performance-based specification for the Virginia Department of Transportation was developed.
There was no significant difference between the unrestrained shrinkage values of latex-modified and microsilica concrete overlay mixtures for the specified time periods. Restrained microsilica concrete specimens generally cracked earlier and more frequently than restrained latex-modified concrete specimens. However, the bridge deck crack and delamination surveys show that construction conditions and quality and traffic type and frequency may have a greater effect on cracking than the overlay material.Master of Science
6
Gilleece, Peter R. V. "An investigation of chloride penetration into modified concretes." Thesis, Queen's University Belfast, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247346.
7
Lone, Ashfaq Hussain. "Engineering and durability properties of concrete modified by redispersible polymer powder." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420813.
8
MUELLER, ANGELA MARIE. "CONNECTION BETWEEN SIMPLE SPAN PRECAST CONCRETE GIRDERS MADE CONTINUOUS-MODIFIED CONNECTIONS." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1021907161.
9
Nguyen, Tom P. "MITIGATING MOISTURE SUSCEPTIBILITY IN HOT-MIX ASPHALT CONCRETE." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/467.
Abstract:
Moisture damage in asphalt pavement has always been a problem for drivers, bicyclists, and pedestrians. The primary objective of this study is to evaluate moisture susceptibility of Hot-Mix Asphalt (HMA) and to investigate mitigation techniques using different antistripping agents. Three types of antistripping agents were used in this research investigation. Two of which are chemical based and the other is hydrated lime. The two types of liquid antistripping agents used in this study include Arr Maz CC LOF-6500 and Arr Maz CC XL-9000. These two liquid antistripping agents were tested at 0.25%, 0.50%, and 0.75%. Hydrated Lime was tested at 1.0%, 1.5%, and 2.0%. The binder used in this study is Asphalt Performance Grade (PG) 64-16 provided by Oxnard Refinery. The crushed stone aggregate used in this study was provided by Cal Portland. This study follows the guidelines of standardized AASHTO, ASTM, and SuperPave mix design for all preparation and test procedures. A total of 120 4-inch by 2.83-inch core specimens with void ratios between 6 to 8 percent were created to test for moisture susceptibility in accordance with the Modified Lottman Test, which tested for Indirect Tensile Strength and Immersion Compression Test, which tested for Compression Strength and Elasticity. During the test, half of these specimens were placed in a hot water bath for 24 hours to condition the sample to represent field performance and the other half were unconditioned. Based on the results, the best liquid antistripping agent is XL-9000 at 0.50% and hydrated lime is most efficient at a dosage rate of 1.5%. The best performing antistripping additive for the value is hydrated lime at 1.5%.
10
Eltayeb, Yousif Mazin Fadl Elhag. "Non-linear bond modelling for reinforced concrete : a newly-modified bond model." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608831.
11
Rossignolo, João Adriano. ""Concreto leve de alto desempenho modificado com SB para pré-fabricados esbeltos - dosagem, produção, propriedades e microestrutura"." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-25102005-104002/.
Abstract:
Esta tese aborda a aplicação da tecnologia dos concretos leves de alto desempenho (CLAD) para a produção de elementos construtivos esbeltos pré-fabricados, tais como painéis estruturais e de vedação e peças para cobertura, apresentando um concreto com propriedades especiais em função da utilização conjunta de látex de estireno butadieno (SB), sílica ativa, superplastificante acelerador e agregados leves nacionais, denominado concreto leve de alto desempenho modificado com SB. Desenvolveu-se um amplo programa experimental para a análise dos concretos, tendo como objetivos o estudo dos processos de dosagem e produção, caracterização das propriedades dos concretos nos estados fresco e endurecido, análise da ductilidade de elementos construtivos esbeltos pré-fabricados submetidos à flexão, assim como a obtenção de informações microestruturais sobre a matriz de cimento e a zona de transição entre o agregado e a matriz de cimento. Os resultados do programa experimental demonstraram que os concretos leves de alto desempenho modificados com SB são extremamente adequados à produção de elementos pré-fabricados esbeltos, devido essencialmente à redução da massa específica e ao excelente desempenho das propriedades relacionadas à resistência mecânica e durabilidade. Nos estudos microestruturais, observou-se que a utilização de sílica ativa e de SB promoveram a diminuição da quantidade e do diâmetro dos poros capilares e da quantidade de hidróxido de cálcio (CH) na matriz de cimento, assim como reduziram a espessura da zona de transição agregado-matriz. Observou-se, também, que os concretos com agregados leves nacionais apresentaram valores da espessura da zona de transição agregado-matriz inferiores aos observados para os concretos com agregados tradicionais.This dissertation deals with the application of the high performance lightweight aggregate concrete (HPLWAC) for the production of thin precast components, such as structural and insulation panels and elements for covering. A concrete with special properties was presented, once the use of styrene-butadiene latex (SBR), silica fume, accelerating superplastificizer and Brazilian lightweight aggregates, named SBR-modified high performance lightweight aggregate concrete. Our main goals in the experimental program were the study of concrete dosage and production, the characterization of concretes properties, the thin precast components analysis, as well as the microstructural study about both cement paste and the interfacial transition zone (ITZ) between aggregate and cement paste. The main results show that the SBR-modified HPLWAC are extremely appropriate to the production of thin precast components, due essentially to the density reduction and to the high performance of mechanical and durability properties. Besides this, it was viewed that the silica fume and SBR use promote the decrease of the amount and diameter of the capillary pores, as well as the amount of calcium hydroxide (CH) in the cement paste. Additionally, they reduce the thickness of the interfacial transition zone between aggregate and cement paste. It was also observed that the concretes with Brazilian lightweight aggregate presented lower values of the interfacial transition zone thickness than the ones observed for the concretes with traditional aggregates (basalt).
12
Ofori-Abebresse, Edward Kwame. "Fatigue resistance of hot-mix asphalt concrete (HMAC) mixtures using the calibrated mechanistic with surface energy (CMSE) measurements approach." Thesis, Texas A&M University, 2006. http://hdl.handle.net/1969.1/4136.
Abstract:
Fatigue cracking is one of the fundamental distresses that occur in the life of a Hot Mix Asphalt Concrete (HMAC) pavement. This load induced distress leads to structural collapse of the entire pavement ultimately and can only be remedied by rehabilitation. There is the need, therefore, for a total understanding of the phenomenon to be able to counter its occurrence. The fatigue resistance of hot mix asphalt concrete (HMAC) has been estimated using approaches ranging from empirical methods to mechanistic-empirical methods to purely mechanistic methods. A continuum mechanics based approach called the Calibrated Mechanistic with Surface Energy (CMSE) measurements was developed at Texas A&M University and recommended after comparison with other approaches in predicting fatigue lives of two Texas HMAC mixtures. The CMSE approach which includes fundamental material properties such as fracture, aging, healing, and anisotropy has been shown to effectively model the parameters that affect the performance of HMAC pavements exposed to repetitive traffic loads. Polymer modified asphalt (PMA) improves pavement performance by providing additional resistance to the primary distresses in flexible pavements, including permanent deformation or rutting, thermal cracking, and fatigue cracking. In this research, the CMSE approach was utilized to estimate the fatigue resistance of HMAC fabricated with asphalts modified with Styrene-butadiene-Styrene (SBS) co-block polymer. These HMAC mixtures were fabricated from materials used on three different road sections in Texas and one test pavement in Minnesota. The CMSE approach was validated as an effective approach for estimating the fatigue resistance of HMAC mixtures with PMA. The effect of oxidative aging on the fatigue resistance of the HMAC mixtures was also verified. Oxidative aging of the mixtures resulted in a corresponding decrease in mixture fatigue resistance. In addition, for two HMAC mixtures with the same binder content and aggregate gradation, the mixture with the softer of the two Performance Grade (PG) binders exhibited greater fatigue resistance. The use of the Utility Theory revealed the possible effects of aggregate geometric properties on the HMAC mixture properties and consequently on their fatigue resistance.
13
Othman, Ayman Mahmoud. "Mechanical performance and fatigue crack growth behavior of polymer-modified asphalt concrete mixtures." Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1058531669.
14
Meneguini, Eduardo Cesar Antonelli. "Avaliação de concreto asfáltico com incorporação de pó de borracha reciclada de pneus, tratada superficialmente com hidróxido de sódio comercial." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/258506.
Abstract:
Orientador: Vladimir Antonio PaulonTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-19T19:32:15Z (GMT). No. of bitstreams: 1 Meneguini_EduardoCesarAntonelli_D.pdf: 4162044 bytes, checksum: 987787614d2ef9437a3937a43815bde9 (MD5) Previous issue date: 2011
Resumo: O principal objetivo deste trabalho é a determinação das principais propriedades do asfalto borracha e das propriedades mecânicas de um concreto asfáltico, tendo, como adição, o uso de borracha moída de pneus usados, tratada com solução de hidróxido de sódio comercial. Obtivemos, com o tratamento superficial da borracha de pneus usados, melhor interface entre a borracha e asfalto, assim como com o concreto asfáltico e a borracha, alcançando sensível aumento da durabilidade do asfalto-borracha. Realizamos, primeiramente, ensaios para caracterizar o asfalto-borracha tratado de acordo com as Normas vigentes, ensaios de durabilidade e, em seguida, ensaios mecânicos do concreto asfáltico. A recuperação elástica do asfalto-borracha utilizando pó de borracha tratada com hidróxido de sódio aumentou em 10% quando comparados com asfalto-borracha sem tratamento. Os resultados demonstraram melhora da estabilidade à estocagem em 42% nos ensaios realizados. Os ensaios de envelhecimento demonstraram que o tratamento do pó de borracha com hidróxido de sódio aumentou sensivelmente sua durabilidade. O ensaio de variação de massa, após o ensaio de envelhecimento, demonstrou que a perda de massa dos corpos de prova utilizando pó de borracha tratada com hidróxido de sódio foi 111% melhor quando comparados com os corpos de prova utilizando pó de borracha sem tratamento. Concluímos que há grande aplicabilidade deste asfalto-borracha na construção civil
Abstract: The main objective of this study is to determine the main properties of the asphalt-rubber and the mechanical properties of an asphalt concrete, with the addition of ground rubber from second-hand tires, treated with a sodium hydroxide commercial solution. We obtained, with the superficial treatment of rubber from second-hand tires, a better interface between the rubber and the asphalt, as well as with the asphalt concrete and the rubber, achieving significant increase in the durability of the asphalt-rubber. We undertake tests to characterize the treated asphalt-rubber according to current standards, durability tests, and then mechanical tests of the asphalt concrete. The elastic recovery of the rubber asphalt with rubber powder treated with sodium hydroxide increased by 10% compared to the untreated rubber asphalt. The results showed an improved stability to storage in 42% in the tests. The aging tests showed that the treatment of the rubber powder with sodium hydroxide significantly increased their durability. The mass change test after the aging test showed that the mass loss of the specimens with rubber powder treated with sodium hydroxide was 111% better when compared to the specimens with rubber powder without treatment. We conclude that there is great use of this rubber asphalt in the construction industry
Doutorado
Saneamento e Ambiente
Doutor em Engenharia Civil
15
Assmann, Alexander [Verfasser], and Hans-Wolf [Akademischer Betreuer] Reinhardt. "Physical properties of concrete modified with superabsorbent polymers / Alexander Assmann. Betreuer: Hans-Wolf Reinhardt." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2013. http://d-nb.info/1036640698/34.
16
Katzer, Jacek. "Special waste fine aggregate concrete modified by silica fume and dispersed reinforcement : doctoral dissertation." Rozprawa doktorska, [s.n.], 1999. http://dlibra.tu.koszalin.pl/Content/1220.
17
Chemlali, Alexander, and Rickard Norberg. "Shear cracks in reinforced concrete in serviceability limit state." Thesis, KTH, Betongbyggnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-169591.
Abstract:
Shear cracks are formed when high oblique tensile stresses, e.g. in thin webs, exceed the tensile strength. A known example of this phenomenon is the extensive shear cracks that were found on the box-girder bridges Gröndal and Alvik, which were mainly caused by insufficient amount of shear reinforcement. In order to avoid this incident (inadequate amount of shear reinforcement), the reinforcement stress is often being assumed as a ultimate limit load in order to fulfill requirements regarding crack control in the service-ability limit state (SLS). This method has led to a overestimation of the reinforcement amount in bridge-design. The aim of this master thesis is therefor to study the shear crack phenomenon and investigate if the amount of shear reinforcement in bridges can be reduced. The first part of this thesis studies the shear cracking behavior in concrete in a plane stress state, while the second part focus how design standards as well as manuals treats shear cracks. Shear cracking in the reinforced concrete panels has been studied with non-linear finite element analysis and compared to experimental testings performed by the University of Toronto. Three different loading conditions for the panels has been analyzed: pureshear, compression or tension combined with shear. The panels are to represent parts of a web in a box-girder bridge that are subjected to in-plane stresses. The non-linear finite element analysis was performed in the FE-program Atena where mainly the crack propagation and crack pattern were studied. The material model in Atena is a smeared crack model with either fixed or rotated crack direction. The panel analysis, in SLS, gave various results. For loading conditions pure shear and tension/shear, the response of the FE-analysis gave a similar result regarding crack pattern but differed in size of crack width. For compression/shear, only micro-cracks developed and did not reflect the result from the real panel tests. This may be the consequence of a too stiff FE-model and the fact that, in the real tests, some cracks occurred due to out-of-plane bending. With methods described in Eurocode 2 and the Swedish handbook for EC2, a shear crack calculation model was created in order to determine the reinforcement stress and crack width. As a reference for the shear crack calculations, a wing structure (1 m strip) has been used which is part of a railway bridge located in Abisko. These calculations were done in order to investigate if the amount of shear reinforcement could be reduced and at the same time fulfill crack control demands in SLS. The bridge department at Tyréns AB concluded, according to a truss model, that the wing section should be reinforced with a amount of 14.1 cm2/m2 while our model showed that the crack width demand could be fulfilled with a equivalent amount of 9.82 cm2/m2, i.e. a reduction around 30%.
18
Najim, Khalid Battal. "Determination and enhancement of mechanical and thermo-physical behaviour of crumb rubber-modified structural concrete." Thesis, University of Nottingham, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.587844.
Abstract:
This study aims are to i) understand and improve the bonding characteristics between crumb rubber and cement paste, and ii) scale-up the use of the material from lab to full-sized reinforced sections. Firstly a parametric investigation was conducted to determine the effect of crumb rubber replacement on the fresh, mechanical and thermo-physical properties of Plain Rubberised Concrete (PRC) and Self-compacting Rubberised Concrete (SCRC) at different w/c ratios. Secondly, the relative effects of different pre-coating/ treating methodologies were evaluated in terms of ITZ porosity, interfacial bonding, and mix air entrapment. These micro structural characteristics were compared to the resultant macro- scale mechanical and dynamic properties in order to evaluate the effectiveness of each treatment method. Thirdly, the large-scale serviceability of steel-reinforced PRC and SCRC was experimentally measured and assessed in terms of mechanical structural behaviour, steel reinforcement bond-slip strength, and material durability including chloride ion diffusion and water penetration. It was found that although crumb rubber incorporation decreases the workability/flowability, compactible mixes could be achieved even with zero-slump. Mortar pre-coating was found to be the most effective surface treatment method in improving both the mechanical behaviour and toughness of PRC and SCRC. It caused an elongation in the micro-crack path length at the rubber/ cement interface due to roughening of the surface morphology, leading to increased fracture energy dissipation! stress relaxation. Crumb rubber incorporation led to unusual thermo-physical properties as thermal conductivity decreased whilst volumetric heat capacity increased, with a pronounced moisture-dependency caused by air entrapment. Consequently, the concrete elements were found to store more heat energy, whilst increasing their resistance to heat exchange with the ambient environment. Interestingly, incorporating crumb rubber offers a significant reduction in interior air temperature fluctuations, which is important in terms of building thermal efficiency and comfort. It was found that both PRC and SCRC could be promising structural materials, with preference to SRCR, to be used for casting indoor-use structural members, especially for domestic buildings.
19
Rahman, Md Mahbubur. "Durability of nano-modified fly ash concrete to external sulfate attack under different environmental conditions." Canadian Society for Civil Engineering (CSCE), 2014. http://hdl.handle.net/1993/24055.
Abstract:
There are still research gaps regarding the effects of key parameters such as water-to-cementitious materials ratio (w/cm), type of binder and pore structure characteristics on the response of concrete to special forms of sulfate attack: physical salt attack (PSA) and thaumasite sulfate attack (TSA). Hence, this study aims at developing an innovative type of concrete: nano-modified fly ash concrete, incorporating various dosages of nano-silica (NS) or nano-alumina (NA) and fly ash, and explores its efficiency in resisting various forms of sulfate attack.
20
Abouelleil, Alaaeldin. "Interaction domain in non-prestressed circular concrete bridge piers using simplified modified compression field theory." Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/18996.
Abstract:
Master of ScienceDepartment of Civil Engineering
Hayder Rasheed
The importance of the analysis of circular columns to accurately predict their ultimate confined capacity under shear-flexure-axial force interaction domain is recognized in light of the extreme load event imposed by the current AASHTO LRFD specification. In this study, various procedures for computing the shear strength are reviewed. Then, the current procedure adopted by AASHTO LRFD 2014, based on the simplified modified compression field theory, is evaluated for non-presetressed circular concrete bridge piers. This evaluation is benchmarked against experimental data available in the literature and against Response 2000 freeware program that depicts interaction diagrams based on AASHTO 1999 requirements. Differences in results are discussed and future improvements are proposed. A new approach is presented to improve the accuracy of AASHTO LRFD calculations. The main parameters that control the cross section shear strength are discussed based on the experimental results and comparisons.
21
Penny, Julie Elizabeth. "An evaluation of heated reclaimed asphalt pavement (RAP) material and wax modified asphalt for use in recycled hot mix asphalt (HMA)." Worcester, Mass. : Worcester Polytechnic Institute, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-010807-113145/.
22
Bozkurt, Emrah Tanoğlu Metin. "Mechanical and thermal properties of non-crimp glass fiber reinforced composites with silicate nanoparticule modified epoxy matrix/." [s.l.]: [s.n.], 2006. http://library.iyte.edu.tr/tezler/master/makinamuh/T000517.pdf.
Abstract:
Thesis (Master)--İzmir Institute of Technology, İzmir, 2006Keywords: polymer composites, Nanoparticles, glass fiber, mechanical properties, thermal properties. Includes bibliographical references (leaves 75-79).
23
Çelik, Osman Nuri. "The engineering properties and fatigue behaviour of asphaltic concrete made with waste shredded tyre rubber modified binders." Thesis, University of Leeds, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271237.
24
Asam, Kalyan Reddy. "Laboratory evaluation of the effect of superpave gradations and polymer modified asphalts on pavement performance." Ohio : Ohio University, 2001. http://www.ohiolink.edu/etd/view.cgi?ohiou1173466416.
25
Su, Haolin. "Properties of concrete with recycled aggregates as coarse aggregate and as-received/surface-modified rubber particles as fine aggregate." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6003/.
Abstract:
This research demonstrates that rubber particle size affects concrete workability and water permeability to a greater extent than fresh density and strength. Concrete with rubber particles of larger size tends to have a higher workability and fresh density than that with smaller particle sizes. However, rubber aggregates with smaller or continuously graded particle sizes are shown to have higher strengths and water permeability resistance. Influence of recycled aggregate and rubber aggregate as part substitutions for natural aggregates on concrete compressive strength was investigated and four equations were proposed to predict compressive strength of the designed concrete. Besides, it is experimentally shown that silane coupling agent (SCA) has a positive effect on reducing the loss of strength of rubber concrete, especially when concrete is weak. This effect becomes more significant with the increase of mass fraction of SCA solution. Experiment results also show a better performance of concrete with SCA-treated rubber than with as-received or sodium hydroxide solution (NaOH)-treated rubber. A brief cost analysis suggests that this approach of surface modification is economically viable. Referring to a provided fatigue load spectrum and fatigue failure mechanism, this method is potentially to be used for rubber concrete in high-cycle fatigue condition.
26
De, Leon John Taani. "Effects of Surface Treatments on National Bridge Inventory Condition Ratings for Concrete Bridge Decks in Utah." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/6736.
Abstract:
Although the application of surface treatments on bridge decks is expected to positively impact bridge deck condition, the effectiveness of specific surface treatments on extending bridge deck life has not yet been quantified on Utah bridge decks. Therefore, the objectives of this research were to develop and analyze deterioration curves for bare concrete bridge decks and decks with specific treatments commonly used in Utah. The scope of this study was determined by the types and extent of electronically available data, including selected static inventory information; maintenance, rehabilitation, and reconstruction histories; and National Bridge Inventory (NBI) condition ratings for the bridge decks. Bridge deck selection criteria and analysis procedures were developed to enable evaluation of the effects of surface treatments on bridge decks in Utah. Characteristics of a typical bridge were defined, and a list of typical bridges was produced to minimize potentially confounding effects of atypical bridge characteristics in comparisons of deterioration curves for monolithic concrete decks, decks with a bituminous overlay, decks with an epoxy overlay, and decks with a latex-modified concrete overlay. Climatic differences were taken into account by grouping bridges not only by overlay type, but also by Utah Department of Transportation region, which was used in this research as a general surrogate for latitude. Individual bridge deck deterioration curves were then combined to generate average deterioration curves aligned by deck construction time and average deterioration curves aligned by deck treatment time. To at least partially account for the potentially different effects of different treatment times, the bridge groups involving overlays were divided into two treatment time categories, early and late, for analysis. The average deterioration curves aligned by deck construction time suggest that certain treatments applied at certain times can achieve average NBI ratings greater than those for monolithic concrete during selected years of bridge deck life. The average deterioration curves aligned by deck treatment time suggest that certain treatments applied at certain times can achieve improvements in NBI ratings that correspond to apparent increases in bridge deck service life. Primarily because the NBI rating system is based mainly on visual inspection, the full benefits of early applications of surface treatments are not apparent in the results of this research. Supplemental perspectives may be gained about the performance of specific surface treatments by evaluating bridge deck deterioration in terms of delamination, half-cell potential, and chloride concentration, for example, which are direct measures of the deterioration process typically experienced by concrete bridge decks in Utah.
27
Weyers, Megan. "Optimised mix composition and structural behaviour of Ultra-High-Performance Fibre Reinforced Concrete." Diss., University of Pretoria, 2020. http://hdl.handle.net/2263/73097.
Abstract:
The overall objective of this study was to develop an optimised Ultra-High-Performance Concrete (UHPC) matrix based on the modified Andreasen and Andersen optimum particle packing model by using available South African materials. The focus of this study was to determine the optimum combined fibre and superplasticiser content for UHPC by using a response surface design.
The UHPC was appropriately designed, produced and tested. Various changes in mechanical properties resulting from different combinations of steel fibre and superplasticiser contents was investigated. The flowability, density and mechanical properties of the designed UHPC were measured and analysed. Both the fibre and superplasticiser content play a significant role in the flowability of the fresh concrete. The addition of fibres significantly improved the strength of the concrete. The results show that the superplasticiser content can be increased if a more workable mix is required without decreasing the strength significantly. The statistical analysis of the response surface methodology confirms that the designed models can be used to navigate the design space defined by the Central Composite Design. The optimum combined fibre and superplasticiser content depend on the required mechanical properties and cost. Using the modified Andreasen and Andersen particle packing model and surface response design methodology, it is possible to efficiently produce a dense Ultra-High-Performance Fibre Reinforced Concrete (UHPFRC) with a relatively low binder amount, low fibre content and good workability.
The effect of heat curing on the mechanical properties was investigated. It was concluded that heat curing is not recommended when considering the long-term strength development. The estimated strength development of concrete obtained by using the fib Model Code 2010 (2013) does not incorporate the detrimental effect of high curing temperatures on long-term strength and therefore overestimate the long-term strengths. The strength estimates for both early and long-term ages can be improved by considering this effect in the strength development functions obtained from fib Model Code 2010 (2013).
The effect of specimen size on the compressive and flexural tensile strength of UHPFRC members were established. It was found that the specimen size has a significant effect on the measured cube compressive strength. Smaller beam specimens showed higher ductility compared to those of the larger beam specimens. The crack width decreased as the beam’s depth decreased. A lower variability was experienced in the beams with limited depth (< 45 mm). Further testing is required to determine whether a span-to-depth ratio of 10 would yield optimum results.
The utilisation of by-products, such as undensified silica fume and fly ash, as cement replacement materials makes UHPFRC sustainable, leading to a reduced life-cycle cost. The calculated Embodied Energy per unit strength (EE/unit strength) and Embodied Carbon per unit strength (EC/unit strength) values for the UHPFRC mixture yield lower values compared to that of the 30 MPa concrete mixture, indicating that UHPFRC can be used to reduce the environmental footprint of the concrete industry.
The inverse analysis method used was successful in providing an improved simplified stress-strain response for the UHPFRC. The analysis provided valuable information into the stress-strain, load-deflection and moment-curvature responses of the UHPFRC. Standard material test results were used to theoretically calculate moment-curvature responses and were then compared to the experimental results obtained.
The study demonstrated that it is possible to efficiently produce a dense and workable UHPFRC with relatively low binder amount and low fibre content. This can result in more cost-effective UHPFRC, thus improving the practical application thereof.Dissertation (MEng)--University of Pretoria, 2020.
Civil Engineering
MEng (Structural engineering)
Unrestricted
28
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.
Abstract:
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
29
Lin, Y. "Optimum design for sustainable 'green' overlays : controlling flexural failure." Thesis, Coventry University, 2014. http://curve.coventry.ac.uk/open/items/b5ba73e5-9cb8-4a0b-ac99-c53b3c3e54ed/1.
Abstract:
The target of the ‘Green Overlays’ research was a cost effective, minimal disruption, sustainable and environmentally friendly alternative to the wholesale demolition, removal and complete reconstruction of the existing structural concrete pavement. The important problem of flexural resistance for strengthening concrete pavements with structural overlays has been scrutinised. A new mix design method for steel fibre reinforced, roller compacted, polymer modified, bonded concrete overlay has been proposed. The mixes developed were characterized of high flexural strength and high bond strength with the old concrete substrate. ‘Placeability’ and ‘compactability’ of the mix were two dominant issues during laboratory investigation. An innovative approach for establishing the relationship between Stress and Crack Face Opening Displacement for steel fibre reinforced concrete beams under flexure was developed. In addition, a new and simple method for calculating the interfacial Strain Energy Release Rate of both, a two-dimensional specimen and a three-dimensional model of the overlay pavement system were developed. This method can be readily and easily used by practicing engineers. Finally, a new test specimen and its loading configuration for measuring interfacial fracture toughness for concrete overlay pavements were established. The interfacial fracture toughness of a composite concrete beam, consisted of steel fibre-reinforced roller compacted polymer modified concrete bonded on conventional concrete and undergoing flexure, was assessed. In summary, this thesis presents four key findings: A new mix design method for steel fibre-reinforced roller compacted polymer modified concrete bonded on conventional concrete. A new method for establishing the fibre bridging law by an inverse analysis approach. A new, simplified method for calculating strain energy release rate at the interface of a composite beam. A new, innovative technique for calculating strain energy release rate at the interface of an overlaid pavement. The thesis contains a plethora of graphs, data-tables, examples and formulae, suitable for future researchers.
30
Shafiei, Kasra [Verfasser], Bernd [Akademischer Betreuer] Hillemeier, Dietmar [Akademischer Betreuer] Stephan, Bernd [Gutachter] Hillemeier, Dietmar [Gutachter] Stephan, and Alexander [Gutachter] Taffe. "Study of the mortar and concrete properties with the use of raw clay minerals and modified calcareous fly ash / Kasra Shafiei ; Gutachter: Bernd Hillemeier, Dietmar Stephan, Alexander Taffe ; Bernd Hillemeier, Dietmar Stephan." Berlin : Technische Universität Berlin, 2017. http://d-nb.info/1156183235/34.
31
Keil, Allessandra, and Michael Raupach. "Polymermodifizierte Feinbetone - Untersuchungen zum Feuchtetransport." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-77927.
Abstract:
Untersuchungen zur Dauerhaftigkeit von ARGlasbewehrung im Textilbeton haben gezeigt, dass durch die Alkalität des Betons in Verbindung mit Feuchtigkeit eine Glaskorrosion hervorgerufen wird, die im Laufe der Zeit zu Festigkeitsverlusten des Glases führt. Eine Möglichkeit, die durch die Glaskorrosion verursachten Festigkeitsverluste zu reduzieren, stellt die Polymermodifikation des Betons dar. Durch die Polymerzugabe wird die Wasseraufnahme der Feinbetonmatrix reduziert, dadurch sinkt der Gehalt an gelösten Alkalien im Bereich der Bewehrung. Um den Einfluss verschiedener Feinbetonmatrices auf die Dauerhaftigkeit von Textilbeton beurteilen zu können, sind u. a. zeit- und tiefenabhängige Informationen zur Feuchteverteilung erforderlich, die durch den Einsatz der NMR-Technik gewonnen werden. Der nachfolgende Artikel beschreibt den Feuchtetransport in einer speziell für den Textilbeton entwickelten Feinbetonmatrix sowie den Einfluss verschiedener Modifikationsstoffe auf das Wasseraufnahmeverhalten des BetonsDurability tests of textile reinforced concrete revealed a loss of strength of the AR-glass reinforcement due to glass corrosion effected by the alkalinity and moisture content of the concrete. In order to reduce this strength loss of AR-glass in cementitious matrices, polymers can be used for concrete modification. The aim of the polymer addition is to reduce the amount of capillary water absorption of the matrix, which reduces the amount of free alkalies closed to the reinforcement. In order to evaluate the effect of the concrete matrix on the durability of TRC, it is necessary to determine the moisture content as functions of time and depth. This data can be obtained by the use of nuclear magnetic resonance (NMR) technique. This paper deals with the moisture transport in a finegrained concrete matrix especially developed for the use in TRC as well as the influence of polymer addition on the water absorption properties of the concrete matrix
32
Bilal, Mustafa. "Relationships Between Felt Intensity And Recorded Ground Motion Parameters For Turkey." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615426/index.pdf.
Abstract:
Earthquakes are among natural disasters with significant damage potentialhowever it is possible to reduce the losses by taking several remedies. Reduction of seismic losses starts with identifying and estimating the expected damage to some accuracy. Since both the design styles and the construction defects exhibit mostly local properties all over the world, damage estimations should be performed at regional levels. Another important issue in disaster mitigation is to determine a robust measure of ground motion intensity parameters. As of now, well-built correlations between shaking intensity and instrumental ground motion parameters are not yet studied in detail for Turkish data. In the first part of this thesis, regional empirical Damage Probability Matrices (DPMs) are formed for Turkey. As the input data, the detailed damage database of the 17 August 1999 Kocaeli earthquake (Mw=7.4) is used. The damage probability matrices are derived for Sakarya, Bolu and Kocaeli, for both reinforced concrete and masonry buildings. Results are compared with previous similar studies and the differences are discussed. After validation with future data, these DPMs can be used in the calculation of earthquake insurance premiums. In the second part of this thesis, two relationships between the felt-intensity and peak ground motion parameters are generated using linear least-squares regression technique. The first one correlates Modified Mercalli Intensity (MMI) to Peak Ground Acceleration (PGA) whereas the latter one does the same for Peak Ground Velocity (PGV). Old damage reports and isoseismal maps are employed for deriving 92 data pairs of MMI, PGA and PGV used in the regression analyses. These local relationships can be used in the future for ShakeMap applications in rapid response and disaster management activities.
33
Macháň, Ladislav. "Využití elektrických vlastností kompozitních materiálů s modifikovanou cementovou matricí." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-234526.
Abstract:
The dissertation thesis is focused on practical use of composite material with modified cement matrix. Especially the area of electrical behavior of composite materials in use has been examined, for strain sensing material. The experimental part solves the problematics of corrosion of carbon and metallic materials in alkaline environment of the cement matrix. The physical design of the sensor and its fabrication using functional composite cement material have been described here. The thesis has also discussed defining the influence of temperature change and humidity change on the change of electrical parameters of integrated sensors. An important part of the thesis is the area of evaluating a series of measurements of electrical parameters under dynamic loading. The thesis analyzes designed measurement method in detail, being suitable to determine electrical properties of cement composite materials including the construction of a monitoring system that enables practical application of sensors in complex structures.
34
Cervantes, Abarca Betsy Pierina, and Meza Liz Katherine Villa. "Análisis comparativo del concreto lanzado con cemento tipo IP y tipo HE en el revestimiento de túneles de la mina Orcopampa – Arequipa." Bachelor's thesis, Universidad Ricardo Palma, 2015. http://cybertesis.urp.edu.pe/handle/urp/1262.
Abstract:
Se viene buscando optimizar la elaboración del concreto lanzado, pero en el proceso se deja de lado el control de calidad por lo cual es indispensable comparar la influencia de un componente primario como el cemento tipo IP y HE.
La presente tesis tiene por objetivo realizar el estudio comparativo de concreto lanzado con cemento portland puzolanico tipo IP vs tipo HE en el revestimiento del túnel de la mina Orcopampa–Arequipa.
Nos ha impulsado a investigar la necesidad de obtener la relevancia en el desempeño y las implicancias del cemento para shotcrete desde una visión técnica, a través de ensayos de campo y laboratorio.
Considerando el enfoque técnico al determinar las diferencias entre el concreto lanzado con cemento Tipo IP y Tipo HE desde el análisis de resistencia a tenacidad y resistencia a la compresión. Realizando un tipo de Investigación básica, cuantitativa, descriptivo, aplicada, de campo con un diseño experimental, según el estudio es cuasi experimental, prospectivo por la cronología de observación, transversal según el número de mediciones, descriptiva, comparativa y explicativa.
Los resultados estadísticos nos demuestran que si existen diferencias significativas de 62 % entre los resultados de la resistencia a la compresión del concreto lanzado cemento Tipo HE sobre el concreto lanzado con cemento Tipo IP en su totalidad de edades ensayadas.
En el análisis estadístico de los ensayos de tenacidad se observa que el cemento Tipo HE tiene una mejor capacidad para absorber energía ya que tiene la característica de desarrollar resistencias a edades tempranas.
It has sought to optimize the development of the shotcrete, but in the process neglects quality control so it is essential to compare the influence of a primary component such as cement type IP and HE.
This thesis aims to conduct a comparative study of shotcrete with IP pozzolanic Portland cement type HE vs kind in the lining of the tunnel Arequipa Orcopampa mine.
It has prompted us to investigate the need for relevance in the performance and the implications of cement shotcrete from a technical view, through field and laboratory tests.
Whereas the technical approach to determine the differences between the shotcrete cement type HE type IP and from the analysis of toughness and resistance to compression. He made a type of Basic, quantitative, descriptive research, applied field with an experimental design, the study is quasi-experimental, prospective timeline for observation cross as the number of measurements, descriptive, comparative and explanatory.
The statistical results show that if there are significant differences between the results 62% of the compressive strength of cement Type HE shotcrete shotcrete on cement type IP fully tested age.
In the statistical analysis of toughness tests it shows that the cement type HE has a better ability to absorb energy and which has the characteristic of developing resistance at early ages.
35
Rohaya, Abdul Malek. "Assessment of Chloride Induced Corrosion and Impressed Current Cathodic Protection Conditions in Repaired Reinforced Concrete." Kyoto University, 2018. http://hdl.handle.net/2433/231995.
36
Eskandarsefat, Shahin <1983>. "Innovative Modified Stone Mastic Asphalt Concretes Containing Composite Poly-functional Fibres for Eco-friendly Paving Applications." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amsdottorato.unibo.it/8811/1/Shahin%20Eskandarsefat%20Thesis%20-%20Final.pdf.
Abstract:
In the present research, a complete study was carried out investigating the effectiveness of novel cellulose-based poly-functional fibres in enhancing the mechanical and performance properties of a virgin and 25% RAP containing Stone Mastic Asphalt (SMA). Therefore, there could be a significant economic advantage and a well-balanced solution between eco sustainability and technology in using RAP in SMA, if it could be used without sacrificing the excellent performance of SMA mixtures. The fibres modification was carried out by adding mineral (glass) fibre, a type of Plastomeric polymer and/or powdered tire rubber. The mix of mineral fibres and rubber with polymeric component was supposed to perform similarly to the regular bitumen modifiers improving the dynamic/mechanical performance of the bituminous binders. The fibrous component contributes to further improving the rheological and thixotropic behaviour of the bituminous mastic. The test program included numerous tests in both binder and mixture-scale in addition to primary microscopic analysis providing a wide range of data to achieve a complete understanding of fibre interaction with binder and its performance in asphalt mixtures. For this purpose, four different cellulose-based fibres (with and without powdered crumb inside), a 50/70 penetration graded neat bitumen, and a 10/40-70 SBS PmB were used to produce the bituminous compounds and mixtures to be investigated through the experimental works. Overall, the results indicate the possibility of modifying asphalt mixtures via modified fibres and the superiority of rubberized fibres in comparison to those of non-rubberized. However, the rubberized mixtures needed enough digestion and interaction temperature and time. In addition, it has been found that while the substitution of 25% virgin materials with RAP could enhance some of the dynamic mechanical properties of SMA, the low-temperature thermal cracking sensitivity increased for all the tested RAP containing mixtures with different fibres rather than the type of modification.
37
Tangvijitsakul, Pattarasai. "Methoxy Poly (Ethylene Glycol) Methacrylate- Based Copolymers on the Applications of Concrete Admixtures, Mesoporous Materials, and Rheology Modifiers." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1442440564.
38
Bruxel, Daiana Frank. "ESTUDO DO COMPORTAMENTO VISCOELÁSTICO DE CONCRETOS ASFÁLTICOS CONVENCIONAIS E MODIFICADOS ATRAVÉS DE ENSAIOS DE LABORATÓRIO E DE ANÁLISE DE DESEMPENHO." Universidade Federal de Santa Maria, 2015. http://repositorio.ufsm.br/handle/1/7901.
Abstract:
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorRoad transport is of great importance for many countries, in Brazil it can be even more extreme, by excessive movement of cargo through this modal. We know that the maintenance costs of roads are high, forcing researchers to find always new alternatives to improve the use of materials, reduce energy consumption, speed up restoration interventions, among others. The goal of this study is to evaluate the behavior of conventional asphalt mixtures of polymers and modified for resistance and deformability. For this study, we used a crushed mineral aggregate skeleton of volcanic origin with framed particle size in the range of C DNIT, coming from the quarry of Santo Antonio da Patrulha RS. 4 types of asphalt binders were used, the CAP 50/70, the TLA CAP, the CAP 60/85 and the TLA FLEX, and the latter two are modified polymers. Compression was done according to Superpave methodology. Tests were carried out to check the mechanical behavior (test Tensile Strength for Diametral Compression (RT) assay Resilience Module (MR) and Dynamic Module test Uniaxial) and later held one performance analysis of mixtures studied by AASHTOWare software. From these investigations it was possible to verify the behavior of the mixtures studied for their resistance, deformability and especially as its durability. It can be said that the choice of the mixture to be used will depend on its applicability. The tests showed that mixtures with TLA Flex achieved the best results, a fact that was confirmed by performance analysis that demonstrated the mixture of TLA Flex with a thickness of 18 cm coating meets all requirements evaluated.
O transporte rodoviário é de grande importância para muitos países, no Brasil isso pode ser ainda mais extremo, pelo excesso de movimentação das cargas através deste modal. Sabe-se que os custos de manutenção das rodovias são elevados, forçando os pesquisadores a encontrar sempre novas alternativas para melhorar o aproveitamento dos materiais, diminuir o consumo de energia, agilizar as intervenções de restauração, entre outros. O objetivo do presente trabalho é avaliar o comportamento de misturas asfálticas convencionais e modificadas por polímeros quanto à resistência e deformabilidade. Para este estudo foi utilizado um esqueleto mineral agregado britado de origem vulcânica com granulometria enquadrada na Faixa C do DNIT, advindos da pedreira de Santo Antônio da Patrulha, RS. Foram utilizados 4 tipos de ligantes asfálticos, o CAP 50/70, o CAP TLA, o CAP 60/85 e o TLA FLEX. A dosagem e compactação foram feitas segundo a metodologia SUPERPAVE. Foram realizados ensaios para verificação do comportamento mecânico (ensaio de Resistência à Tração por Compressão Diametral (RT), ensaio de Módulo de Resiliência (MR) e ensaio de Módulo Dinâmico Uniaxial) e posteriormente realizada uma análise desempenho das misturas estudadas através do software AASHTOWare. A partir destas investigações foi possível verificar o comportamento das misturas estudadas quanto a sua resistência, deformabilidade e principalmente quanto ao seu desempenho. Pode-se afirmar que a escolha da mistura a ser utilizada dependerá do cumprimento de uma série de quesitos de projeto. Os ensaios evidenciaram que as misturas com TLA Flex obtiveram os melhores resultados, fato este que foi confirmado através da análise de desempenho que comprovou que esta mistura, com espessura de 18 cm de revestimento cumpre com todos os requisitos de projeto.
39
Yeh, Chun-Ko, and 葉峻閣. "A Modified Underwater Self-Compacting Concrete." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/36170526012628891231.
Abstract:
碩士國立交通大學
土木工程學系
98
There are many concrete structures are constructed under water, such as footings, piers, and slurry walls. In the past, rich mix design concrete were used to obtain a low slump, and high viscosity. The engineers are concerned about the mortar dispersion after the concrete is placed in water or the water was mixed with concrete which yields a higher w/c. If the concrete used in underwater condition can have the self-compacting ability, a much better quality of concrete can be expected. This study focused on the non-dispersion, less setting time, higher strength, and self-compacting concrete. Various admixtures were tried and the test results showed that the initial setting time can be 3-4 hours less and final setting time 4-5 hours less. The anti-washout tests were also performed. The concrete placed in water showed a compressive strength at 28 days of 6000 psi. The shrinkage was also measured. Thus a new underwater self-compacting concrete was developed to guarantee the quality, safety, and economy. Key words: underwater self-compacting concrete, anti-washout, tremie
40
Chen, shnin huang, and 陳世晃. "The study of modified asphlt concrete standard." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/70996986575689063492.
Abstract:
碩士國立中央大學
土木工程學系
85
ABSTRACTkeyword: visbreaking , toughness , SMA , SEMRecently , many roads have already made use of modified asphalt in Taiwan .Up to now ,there are no standards of modified asphalt in Taiwan ,and we usually use ASTM or JIS .Therefore it is urgent to establish the standards suitable for Taiwan. The research focuses on the interrelation between toughness and tenacity of SMA used in Europe. Besides, we also research the bond effect between asphalt and polymer before and after visbreaking.The result of Rheology show that the asphalt cement of non- visbreaking have performs better than it of visbreaking , In addition , the asphalt cement of non-visbreaking have more chain entanglement and crosslink form FE-SEM(Field Emission Scanning Electron Microscope ) test. In a word , the asphalt cement of non-visbreaking is a better base asphalt .Form the result of research , the more polymer additive , the higher ability of deformation resistant of asphalt cement it shows. For the modified asphalt concrete, the mechanic property of asphalt cement would not reflect on the asphalt concrete .According to toughness test of the research , the toughness value at 10.8cm deformation has high degree positive relation with performance test. We can see that 10.8cm is very closed to the effective deformation of asphalt cement assumed by us. Stonic Mastic Asphalt really can be used in Taiwan to improve the rutting at high temperature, and consequently to improve the gradation and aggregate is another important problem. At last ,we refer to JIS , ASTM and the result of this research and elementary criterion draft for posterior research .
41
Yu-WenTseng and 曾榆雯. "Performance Evaluation of Modified and ReclaimedAsphalt Concrete." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/up57y3.
42
Sujjavanich, Suvimol. "Early age performance of latex-modified concrete bridge deck overlays." Thesis, 1996. http://hdl.handle.net/1957/33993.
Abstract:
Environmental factors and physical properties of latex modified concrete (LMC)
are hypothesized to contribute to early age cracking in bridge deck overlays. Cracking
permits the ingress of moisture and aggressive solutions into the substrate and may
contribute to other subsequent distresses. Understanding the material properties and
mechanisms involved is necessary to minimize these distresses.
This research consisted of a two part study: first, the development of LMC
strength and fracture properties at ages ranging from 5 hours to 28 days was studied, and
secondly, the effects of the environment on LMC distresses were modelled.
Environmental conditions: temperature, solar energy, and wind speed were determined
from weather records. A fracture mechanics based model, the Fictitious Crack Model
(FCM), incorporating finite element analyses and superposition techniques was employed
with material properties from the first part of study on LMC performance. Different
bilinear strain softening diagrams were used to predict fracture performance at different
ages. The predictions agreed well with the test data. The impacts of temperature
differentials on crack development were studied. The shrinkage effect was also indirectly
incorporated through the temperature analysis.
The material properties study indicated significant changes in strength, deformability
and fracture properties, particularly during the early age. The developments differ slightly from
conventional concrete. Test results indicated a significant improvement in reducing and
bridging microcracks, especially in the prepeak-load region. Fracture toughness and
deformability increased significantly with time. Fracture energy varied from 2.3 to 133.1 N/m,
depending on age, and to some degree, on notch depth ratio.
In the second stage, the FCM provided a reasonable prediction for crack initiation
and propagation when only temperature effects are of concern. Age, surface conditions
and structural restraint strongly affect crack resistance of the overlays. Only slight effects
were observed from the overlay thickness in the study range (51-76 mm). Shallow preexisting
cracks possibly reduce the crack resistance of the overlay about 30 percent. A
prolonged moist cure for 48 hours after placing is suggested to reduce the risk of
cracking. With available environmental information, it is possible to develop guidelines for
appropriate environmental conditions for LMC bridge deck construction to minimize the
risk of early age cracking.Graduation date: 1997
43
WANG, LIEN-PING, and 王連斌. "Research of Regeneration Modified Dense Graded Concrete Asphalt." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/96211140506736759301.
Abstract:
碩士高苑科技大學
土木工程研究所
104
There is close relationship between road works and the materials that asphalt concrete after processing is one of them. Asphalt concrete after processing can be reused after design and processing. The performance of reused asphalt concrete after processing is not worse than the performance of the fresh concrete, and the reused asphalt concrete after processing is in accordance with the needs of environmental sustainability. The eliminating materials of highway is better than general eliminating materials for the high standard on modified asphalt and aggregates. In this study, highway eliminating materials is used. Because of its bitumen eliminating material containing a polymer composition, the viscosity of bitumen recovered by conventional techniques can not be accurately determined. Hence, the fresh asphalt modified Ⅲ is simulated aging by thin film oven aging test to imitate the actual aging of the asphalt materials. A modified type Ⅲ fresh asphalt were formulated to target viscosity 5000Poise which was mixed by regenerated catalyst and regeneration of asphalt 15000Poise concrete (Recycled asphalt concrete) which was mixed by different viscosity of AC-20. There are 40% of recycled asphalt concrete modified in eliminating materials (Reclaimed asphalt Pavement, RAP ). We set the same grading curve conditions after Marshall test and get the optimal oil content. Stable value, indirect tension strength retention, flooding exfoliation, resilient modulus static creep and rutting were tested next. In order to compare the performance of the mechanical properties of RAC, we mixed the AC-20 and modified asphalt type Ⅲ full of fresh asphalt to get the mechanical properties. The mechanical properties of modified asphalt type Ⅲ in adding 40% eliminating materials are better than eliminating AC-20 in this study.
44
Badr, A., and Ashraf F. Ashour. "Modified ACI Drop-Weight Impact Test for Concrete." 2009. http://hdl.handle.net/10454/3631.
Abstract:
ACI Committee 544's repeated drop-weight impact test for concrete is often criticized for large variations within the results. This paper identifies the sources of these large variations and accordingly suggests modifications to the ACI test. The proposed modifications were evaluated and compared to the current ACI test by conducting impact resistance tests on 40 specimens from two batches of polypropylene fiber-reinforced concrete (PPFRC). The results obtained from both methods were statistically analyzed and compared. The variations in the results were investigated within the same batch and between different batches of concrete.
The impact resistance of PPFRC specimens tested with the current ACI test exhibited large coefficients of variation (COV) of 58.6% and 50.2% for the first-crack and the ultimate impact resistance, respectively. The corresponding COV for PPFRC specimens tested according to the modified technique were 39.4% and 35.2%, indicating that the reliability of the results was significantly improved.
It has been shown that, using the current ACI test, the minimum number of replications needed per each concrete mixture to obtain an error below 10% was 41 compared to 20 specimens for the modified test. Although such a large number of specimens is not good enough for practical and economical reasons, the reduction presents a good step on the development of a standard impact test.
45
Chih-HongLi and 李志鴻. "Engineering Properties of Recycled Modified Asphalt Concrete (RMAC)." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/29ecz2.
Abstract:
碩士國立成功大學
土木工程學系
104
There are few domestic studies of Reclaimed Modified Asphalt Pavement (RMAP) now. In this study, AC-20 and AC-10 were respectively used as virgin asphalt and softening agent. RA-5 was used as rejuvenating agent. In order to compare engineering and volumetric properties for different mix designs, asphalt content and grading curve of mix designs were adjusted to the same as much as possible. In this study, conducting Marshall test of stability, flow, indirect tension, resilient modulus, residual strength and Cantabro test with mixture conditioning to evaluate virgin asphalt concrete, Recycled Asphalt Concrete (RAC) and Recycled Modified Asphalt Concrete (RMAC). In addition to flow value, engineering properties of RMAC and RAC were all in compliance with specification requirements, and reclaimed materials still obviously had hardening effect. RAC and RMAC had significant differences in Cantabro test, but there were no significant differences between short-term aging and long-term aging. When adding rejuvenating agent RA-5, V.M.A. of RAC and RMAC would decline with the increase of the proportion of reclaimed materials；but when adding the softening agent, V.M.A of RAC in a high proportion of reclaimed material would rise due to porosity increasing, and RMAC would still control the porosity of 4%. From the results of engineering and volumetric properties, it is feasible to use RMAP in asphalt pavement when proportion of reclaimed materials are less than 60%. Because of the effect of black rock, the surface of specimens would generate binder spots and bleeding.
46
KUO-JUNG, CHENG, and 鄭國榮. "Research of Regeneration Modified Corase Graded Asphalt Concrete." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/jh4266.
Abstract:
碩士高苑科技大學
土木工程研究所
104
Taiwan has limited resources, therefore we rely on import for petroleum. Besides, sand and stone are decreasing. The reuse of reclaimed asphalt pavement (RAP) will reduce the environmental pollution and be friendly to the environment. This study investigated the use of aging highway which is modified reclaimed asphalt pavement, added the new pellets formulated into coarse grade, modified the asphalt and added the regeneration agent; It could be used as laying the road base after heating and stirring the regeneration. Because of the removed asphalt containing high molecular polymers, the viscosity of recycled asphalt is not easy to get the exact result by the normal test way. By comparing with the documents, we could get the actual ageing of the reclaimed asphalt pavement. Then we use the regenerant, add the different viscosity of AC-20, change into the Ⅲ type fresh asphalt, and divide into the recycled asphalt concrete of the 5000 Poise and the 15000 Poise target viscosities. In order to explore reclaimed asphalt pavement accounted for 40% of changed recycled asphalt concrete, we choose coarse graded asphaltic concrete to get the best asphalt content from Marshell test. Then we could know the testament of the stable value, the indirect tension strength retention, the immersion stripping test, the resilient modulus and the static creep test, etc. From the test results of the effectiveness comprehensive assessment, we know that the effect of changed recycled coarse graded asphaltic concrete is better than fresh coarse graded asphaltic concrete and the target viscosity 15000 Poise ( modified III asphalt) is better than the target viscosity 5000 Poise (AC-20). Both of them are able to be the marital subbase of building road.
47
Badr, A., and Ashraf F. Ashour. "Modified ACI Drop-Weight Impact Test for Concrete." 2005. http://hdl.handle.net/10454/7669.
Abstract:
yesACI Committee 544’s repeated drop-weight impact test for concrete is often criticized for large variations within the results. This paper identifies the sources of these large variations and accordingly suggests modifications to the ACI test. The proposed modifications were evaluated and compared to the current ACI test by conducting impact resistance tests on 40 specimens from two batches of polypropylene fiber-reinforced concrete (PPFRC). The results obtained from both methods were statistically analyzed and compared. The variations in the results were investigated within the same batch and between different batches of concrete. The impact resistance of PPFRC specimens tested with the current ACI test exhibited large coefficients of variation (COV) of 58.6% and 50.2% for the first-crack and the ultimate impact resistance, respectively. The corresponding COV for PPFRC specimens tested according to the modified technique were 39.4% and 35.2%, indicating that the reliability of the results was significantly improved. It has been shown that, using the current ACI test, the minimum number of replications needed per each concrete mixture to obtain an error below 10% was 41 compared to 20 specimens for the modified test. Although such a large number of specimens is not good enough for practical and economical reasons, the reduction presents a good step on the development of a standard impact test.
48
Yu-TingChen and 陳禹廷. "Engineering Properties of Modified and Recycled Asphalt Concrete." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/p5pk52.
Abstract:
碩士國立成功大學
土木工程學系
106
Fatigue cracking is one of the broken types of asphalt pavement in Taiwan. In this study, the engineering properties of asphalt concrete were tested to investigate the cracking behavior of asphalt concrete. The gradation of 19mm maximum aggregate size was adopted to control asphalt dosage and gradation curve. The results of water resistance showed that the AR-8000M and the SBS modified asphalt whose softening point was over 70°C, had good tensile strength ratio, indicating that appropriate modified effect was helpful for water resistance; besides, with the increase of the appending proportion for the reclaimed asphalt pavement (RAP), there was a downward trend in the result of indirect tension, affecting the ability of water resistance. According to the semi-circular bending test results, as the stiffness of asphalt increases, the strain energy to failure will increase. The modified asphalt concrete has better cracking resistance than the traditional asphalt concrete. The result of semi-circular bending test shows the contribution of polymer addition to asphalt concrete; in addition, The results of strain energy to failure and critical strain energy release rate of recycled asphalt concrete (RAC) show that 40% RAP of recycled asphalt concrete has better cracking resistance than traditional asphalt concrete. But with the RAP addition increasing, the cracking resistance of the recycled asphalt concrete will diminish.
49
ZHANG, WEI-FA, and 張維發. "Study on unsaturated polyester modified concrete without using water." Thesis, 1991. http://ndltd.ncl.edu.tw/handle/02088348423389635923.
50
楊景鼎. "A Study on Using Modified Concrete Rheometer to Measure the Rheological Behavior of Fresh Concrete." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/66872412375460062076.
Abstract:
博士國立交通大學
土木工程學系
99
The modified concrete rheometer (MCR) apparatus developed in this study is based on existing concrete rheometers, the main differences being the gap size and measurement method, and thus the interpretation of the results. The gap between the inner cylinder wall and the tip of the vane was set to 6.4 times the diameter of the largest coarse aggregate in order to reduce interaction between the aggregate and the wall and the friction force from the wall. The MCR apparatus was used to measure yield torque directly at different low rotational speeds (above 0.003 rev/sec). A study of the yield torque and viscosity of forty fresh concrete mixtures was also made, with a particular focus on self-compacting concrete or self-consolidating concrete (SCC), and the results were compared with those obtained using other workability tests. The test results showed that the MCR can differentiate between conventional concrete (CC), powder-type SCC and SCC with viscosity-modifying agents (VMA). The rheological behavior of powder-type SCC was found to be influenced by the composition of Class F fly ash and ground granulated blast-furnace slag (GGBFS), and this type of concrete exhibited a wider range of viscosity and yield torque values. Despite the lower powder content and larger water to binder ratio (w/b), the viscosity of VMA-type SCC was shown to be slightly lower than that of powder-type SCC, and the values were clustered together within a certain range; thus, the workability of SCC containing VMA is more easily controlled. In addition, the MCR apparatus can also be applied to CC of differing viscosity and yield torque, thus making this apparatus suitable for determination of the workability of all kinds of fresh concrete.