The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Kequan Yu - One of the best experts on this subject based on the ideXlab platform.
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flexural strengthening of rc beams with cfrp grid reinforced ecc matrix
Composite Structures, 2018Co-Authors: Zhoudao Lu, Kequan Yu, Xu YangAbstract:Abstract This paper investigates the flexural performance of a series of RC beams externally bonded with carbon fiber-reinforced polymer (CFRP) grid-reinforced engineered cementitious composite (ECC) matrix. A total of 15 RC beams, including three control and twelve strengthened, were prepared and tested. The test variables included the longitudinal reinforcement ratio, the strengthening configurations that consisted of different cementitious matrices (ECC versus Epoxy Mortar), different installation methods (prefabricated versus cast-in-place), and different stiffness of CFRP grids. The test results showed that ECC is an ideal cementitious matrix for the strengthening applications where FRP grids are used as the external reinforcement. The flexural strengthening configuration using the Epoxy adhesive to bond prefabricated CFRP grid-reinforced ECC plate proved to be the most efficient solution. For such configuration, the plate-end debonding can be avoided and the mid-span debonding can be almost suppressed. Flexural capacity analysis was conducted and demonstrated that the plane section assumption is valid and the full strength composite action can be nearly achieved for the strengthening system. The average ratio of the predicted peak loads to the experimental ones of the strengthened RC beams was 1.05.
Xu Yang - One of the best experts on this subject based on the ideXlab platform.
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flexural strengthening of rc beams with cfrp grid reinforced ecc matrix
Composite Structures, 2018Co-Authors: Zhoudao Lu, Kequan Yu, Xu YangAbstract:Abstract This paper investigates the flexural performance of a series of RC beams externally bonded with carbon fiber-reinforced polymer (CFRP) grid-reinforced engineered cementitious composite (ECC) matrix. A total of 15 RC beams, including three control and twelve strengthened, were prepared and tested. The test variables included the longitudinal reinforcement ratio, the strengthening configurations that consisted of different cementitious matrices (ECC versus Epoxy Mortar), different installation methods (prefabricated versus cast-in-place), and different stiffness of CFRP grids. The test results showed that ECC is an ideal cementitious matrix for the strengthening applications where FRP grids are used as the external reinforcement. The flexural strengthening configuration using the Epoxy adhesive to bond prefabricated CFRP grid-reinforced ECC plate proved to be the most efficient solution. For such configuration, the plate-end debonding can be avoided and the mid-span debonding can be almost suppressed. Flexural capacity analysis was conducted and demonstrated that the plane section assumption is valid and the full strength composite action can be nearly achieved for the strengthening system. The average ratio of the predicted peak loads to the experimental ones of the strengthened RC beams was 1.05.
Lech Lichołai - One of the best experts on this subject based on the ideXlab platform.
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Long-Term Chemical Resistance of Ecological Epoxy Polymer Composites
Polish Society of Ecological Engineering (PTIE), 2018Co-Authors: Bernardeta Debska, Lech LichołaiAbstract:Resin concretes belong to a small group of building materials which, besides high strength parameters, also have a very good chemical resistance. This is confirmed by the studies carried out by various research institutions around the world. However, there is little data on the behaviour of composite resin exposed to corrosive solutions for an extended period of time. This article presents the results of the research on weight changes in samples of Epoxy Mortar modified with poly(ethylene terephthalate) glycolysates, immersed for 5 years in four different aggressive media i.e. 10% aqueous solutions of sulphuric and nitric acids, sodium hydroxide, and sodium chloride. The actual average weight changes obtained were compared with the data calculated on the basis of the regression functions fitted to the data recorded after 3.5 years of exposure. This allowed verification of the model selection correctness and evaluation of the effectiveness of the fitted regression curve. In the case of aqueous sodium hydroxide and sodium chloride solutions, it can be assumed that the logarithmic model describes weight changes well. It was observed that the weight of the samples exposed to NaCl solutions and NaOH stabilizes over prolonged monitoring time and reaches a plateau. However, the weight changes in Mortar samples immersed for 5 years in aqueous solution of sulphuric and nitric acids quite significantly differ from the data calculated on the basis of the trend line fitted to the results of the tests carried out after 3.5 years of exposure. It seems that the better solution in this case is the selection of an exponential model. In addition, placing the logarithmic trendlines for all corrosive media together on a chart allows to note which of the solutions is the most aggressive. It was found that after 5 years of immersion in aqueous solutions of acids, Mortar samples became brittle, and the observation of their fractures confirmed the weakness of the connection on the resin/aggregate phase boundary. Changes in the appearance of the samples were also noted, namely the surface of samples submerged in a solution of nitric acid strongly yellowed, and those treated with sulphuric acid were tarnished
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The effect of the type of curing agent on selected properties of Epoxy Mortar modified with PET glycolisate
Construction and Building Materials, 2016Co-Authors: Bernardeta Dębska, Lech LichołaiAbstract:Abstract In the area of chemical applications in construction they are new materials, which do not have equivalents in nature. Polymers can be used to successfully replace traditional materials of the wood, metal or ceramics types. Among the polymers, one of the most important groups are Epoxy resins, whose popularity stems from a combination of excellent mechanical and chemical properties. At the same time, the characteristics of Epoxy resins are strongly dependent on the type and quantity of curing agent. The article presents the results of research on Epoxy Mortar modified with PET glycolisate, hardened by using three different amine curing agents. Characteristics such as flexural and compressive strength and water absorption were determined. The results were subjected to statistical analysis and compared, indicating the curing agent that allows the obtainment of a composite that is characterized by the highest values of the tested parameters.
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The selected mechanical properties of Epoxy Mortar containing PET waste
Construction and Building Materials, 2015Co-Authors: Bernardeta Dębska, Lech LichołaiAbstract:Abstract Modern concrete-like polymer composites rate now among the most important materials in building industry. However, their general use is rather limited because their production is more expensive than that of ordinary concretes, first of all because of the high cost of resins applied. For these reason as well as on account of the idea of sustainable development, it is very important to conduct research on how to use polymer waste (mainly plastic waste) for the modification of building materials. The article presents the results of strength and hardness tests on Epoxy Mortars produced by partially substituting their resin binder with glycolisates obtained from poly(ethylene terephthalate) waste (PET). Structural study on the glycolisates was conducted by means of IR and NMR spectroscopy. Besides, a differential scanning electron microscope was used to photograph the fractures of the samples of the composites. The global extrema of the parameters investigated were determined based on the results of the STATISTICA program aided calculations. This allowed identifying the area of input mixture content changes for which the specimens of the composite showed the best properties for all the three determined parameters. Additionally, it was proved that there are cause-and-effect relationships between the chemical structure of the glycols used for the glycolysis and the strength properties of the composites obtained. The investigation conducted confirmed that there is a possibility of using waste materials in the production of Mortar. Since they have always been an environmental problem, their utilization will help to apply the principles of sustainable development in the processes of obtaining new materials.
Indong Jang - One of the best experts on this subject based on the ideXlab platform.
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The effects of sand washing waste and microwave curing on the dimensional stability of Epoxy Mortar
Construction and Building Materials, 2020Co-Authors: B.k. Rajeshwar, Dinberu Molla Yemam, Indong JangAbstract:Abstract Sand washing waste (SWW), a by-product of the aggregate production process, consists of microfine particles and has limited practical applications in cement composites. In this study, SWW was considered as a potential filler for Epoxy Mortars. The effect of SWW on the dimensional stability of Epoxy Mortar specimens was investigated in terms of linear shrinkage and coefficient of thermal expansion (CTE). In addition, the effects of curing methods (open air and microwave) on the dimensional stability of Epoxy Mortar were assessed. The open air-cured specimens containing an optimum level of SWW exhibited improved dimensional stability compared to pure Epoxy; however, increasing the content of the SWW in Epoxy Mortar led to increased shrinkage. It was also noted that microwave-cured specimens had lower shrinkage, as well as expansion, in comparison to open air-cured specimens.
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Effect of microwave on mechanical properties of Epoxy Mortar
Construction and Building Materials, 2019Co-Authors: B.k. Rajeshwar, Indong JangAbstract:Abstract The influence of microwave exposure on the mechanical properties of Epoxy Mortar was investigated in this study. First, the setting time and compressive strength of the Epoxy Mortar cured using microwave were evaluated. Next, the bond between the Epoxy Mortar and concrete substrate was assessed with a focus on the effect of moisture content of the substrate by pull-out and three-point bending tests. The results indicate that microwave curing can be effectively implemented for Epoxy Mortar, and it can facilitate the development of adequate strength quicker than room-temperature curing. Further, the moisture content of the substrate significantly affects the bond behavior. Conclusively, microwave can improve the strength and bond properties of Epoxy Mortar, facilitating an effective concrete repair.
Zhoudao Lu - One of the best experts on this subject based on the ideXlab platform.
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flexural strengthening of rc beams with cfrp grid reinforced ecc matrix
Composite Structures, 2018Co-Authors: Zhoudao Lu, Kequan Yu, Xu YangAbstract:Abstract This paper investigates the flexural performance of a series of RC beams externally bonded with carbon fiber-reinforced polymer (CFRP) grid-reinforced engineered cementitious composite (ECC) matrix. A total of 15 RC beams, including three control and twelve strengthened, were prepared and tested. The test variables included the longitudinal reinforcement ratio, the strengthening configurations that consisted of different cementitious matrices (ECC versus Epoxy Mortar), different installation methods (prefabricated versus cast-in-place), and different stiffness of CFRP grids. The test results showed that ECC is an ideal cementitious matrix for the strengthening applications where FRP grids are used as the external reinforcement. The flexural strengthening configuration using the Epoxy adhesive to bond prefabricated CFRP grid-reinforced ECC plate proved to be the most efficient solution. For such configuration, the plate-end debonding can be avoided and the mid-span debonding can be almost suppressed. Flexural capacity analysis was conducted and demonstrated that the plane section assumption is valid and the full strength composite action can be nearly achieved for the strengthening system. The average ratio of the predicted peak loads to the experimental ones of the strengthened RC beams was 1.05.