The usage of supplementary cementitious materials often alters the chemical composition of the main binding phase in modern concrete, i.e., C-S-H. The consequent influence on the mechanical properties is not completely clear, due to the lack of study on the inter-particle interaction of C-S-H. Recent papers published by the authors have provided experimental evidence, and in this work, a subsequent numerical study based on discrete element method (DEM) is provided. Models of compacted C-S-H were established with various surface interaction parameters between particles, e.g., surface energy and friction coefficient, and subjected to simulated triaxial load. The results revealed that increased surface energy and friction coefficient enhance the stiffness of C-S-H and densifies its microstructure. The work may inspire methods to design stronger cementitious composite materials.
{"title":"Discrete Element Modelling of Powder-compacted C-S-H Matrix","authors":"Zhe Zhang, Guoqing Geng","doi":"10.3151/jact.21.889","DOIUrl":"https://doi.org/10.3151/jact.21.889","url":null,"abstract":"</p><p>The usage of supplementary cementitious materials often alters the chemical composition of the main binding phase in modern concrete, i.e., C-S-H. The consequent influence on the mechanical properties is not completely clear, due to the lack of study on the inter-particle interaction of C-S-H. Recent papers published by the authors have provided experimental evidence, and in this work, a subsequent numerical study based on discrete element method (DEM) is provided. Models of compacted C-S-H were established with various surface interaction parameters between particles, e.g., surface energy and friction coefficient, and subjected to simulated triaxial load. The results revealed that increased surface energy and friction coefficient enhance the stiffness of C-S-H and densifies its microstructure. The work may inspire methods to design stronger cementitious composite materials.</p>\u0000<p></p>","PeriodicalId":14868,"journal":{"name":"Journal of Advanced Concrete Technology","volume":"5 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138519136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The purpose of this study is to clarify the bond behavior between rebar and concrete during DEF expansion and pullout testing. The details of the expansion test and the influence of reinforcing bar on DEF expansion have been precisely described in Part I. In Part II, the data related to the bond test is described. The change in bond behavior due to DEF expansion is investigated via the one-end pullout test and the influence of DEF expansion on the bond behavior is discussed. The local bond behavior (slip and bond stress) during the pullout test of the specimens without stirrups is observed to be dramatically changed by DEF expansion. Regarding the specimens with stirrups, failure did not occur during the pullout test and the local bond behavior slightly changed as in the case without stirrups. From the experimental results, a conceptual diagram is proposed to explain the bond behavior during DEF expansion and the pullout test based on the general conceptual understanding of the bond. It can be considered that the direction of local slip and local bond stress during the pullout test is opposite to that during the expansion process. This results in the observed complex local bond behavior during DEF expansion and the pullout test and the effect of stirrups on DEF expansion.
{"title":"Influence of Reinforcing Rebar on Expansion due to Delayed Ettringite Formation along the Bonding Length – Part II: Bond Performance of Reinforced Concrete Affected by DEF Expansion","authors":"Taito Miura, Misato Fujishima, Yuichiro Kawabata, Stéphane Multon, Renaud-Pierre Martin, Naoshi Ueda, Yuya Takahashi, Shingo Asamoto, Jean-Francois Seignol","doi":"10.3151/jact.21.869","DOIUrl":"https://doi.org/10.3151/jact.21.869","url":null,"abstract":"</p><p>The purpose of this study is to clarify the bond behavior between rebar and concrete during DEF expansion and pullout testing. The details of the expansion test and the influence of reinforcing bar on DEF expansion have been precisely described in Part I. In Part II, the data related to the bond test is described. The change in bond behavior due to DEF expansion is investigated via the one-end pullout test and the influence of DEF expansion on the bond behavior is discussed. The local bond behavior (slip and bond stress) during the pullout test of the specimens without stirrups is observed to be dramatically changed by DEF expansion. Regarding the specimens with stirrups, failure did not occur during the pullout test and the local bond behavior slightly changed as in the case without stirrups. From the experimental results, a conceptual diagram is proposed to explain the bond behavior during DEF expansion and the pullout test based on the general conceptual understanding of the bond. It can be considered that the direction of local slip and local bond stress during the pullout test is opposite to that during the expansion process. This results in the observed complex local bond behavior during DEF expansion and the pullout test and the effect of stirrups on DEF expansion.</p>\u0000<p></p>","PeriodicalId":14868,"journal":{"name":"Journal of Advanced Concrete Technology","volume":"33 3","pages":""},"PeriodicalIF":2.0,"publicationDate":"2023-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138519135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The purpose of this study is to evaluate the experimental and analytical performance of untreated recycled aggregates (URA), chemically treated recycled aggregates (ARA), and customized chemical-mechanically processed recycled aggregates (AmRA). The compressive strength, split tensile strength, flexural strength, fracture energy, and modulus of elasticity of concrete consisting of AmRA (AmRC) are greater than those composed by URA (URC) by 33.88%, 5.87%, 55.07%, 28.84%, and 50.80%, and those of ARA (ARC) by 10.89%, 21.41%, 29.44%, 55.33%, and 34.48%, respectively. AmRC has abrasion resistance around 52.03% and 43.07% higher than URC and ARC. Chemical treatment reduces porosity and microcracks in mortar adhered to aggregate. As a result of the customized mechanical treatment, the surface characteristics are highly uniform and dense. The high-quality surface texture, reduced porosity, and microcracks in the mortar adhering to the AmRA significantly strengthen interfacial transitions zones. Thus, AmRC achieves physical, mechanical, and durability properties close to or superior to natural aggregate (NA) concrete (NAC). Moreover, there is a strong correlation between compressive strength and split tensile strength, flexural strength, fracture energy, and modulus of elasticity of AmRC with URC and ARC. The most interesting observation of the present research is the equivalency in sorptivity of AmRC and NAC. The present study uses the URA produced by crushing concrete cubes in the laboratory.
{"title":"Experimental and Analytical Performance of Recycled Aggregates Produced by Customized Chemical-Mechanical Treatment","authors":"Babu Lal Chauhan, Gyani Jail Singh","doi":"10.3151/jact.21.903","DOIUrl":"https://doi.org/10.3151/jact.21.903","url":null,"abstract":"The purpose of this study is to evaluate the experimental and analytical performance of untreated recycled aggregates (URA), chemically treated recycled aggregates (ARA), and customized chemical-mechanically processed recycled aggregates (AmRA). The compressive strength, split tensile strength, flexural strength, fracture energy, and modulus of elasticity of concrete consisting of AmRA (AmRC) are greater than those composed by URA (URC) by 33.88%, 5.87%, 55.07%, 28.84%, and 50.80%, and those of ARA (ARC) by 10.89%, 21.41%, 29.44%, 55.33%, and 34.48%, respectively. AmRC has abrasion resistance around 52.03% and 43.07% higher than URC and ARC. Chemical treatment reduces porosity and microcracks in mortar adhered to aggregate. As a result of the customized mechanical treatment, the surface characteristics are highly uniform and dense. The high-quality surface texture, reduced porosity, and microcracks in the mortar adhering to the AmRA significantly strengthen interfacial transitions zones. Thus, AmRC achieves physical, mechanical, and durability properties close to or superior to natural aggregate (NA) concrete (NAC). Moreover, there is a strong correlation between compressive strength and split tensile strength, flexural strength, fracture energy, and modulus of elasticity of AmRC with URC and ARC. The most interesting observation of the present research is the equivalency in sorptivity of AmRC and NAC. The present study uses the URA produced by crushing concrete cubes in the laboratory.","PeriodicalId":14868,"journal":{"name":"Journal of Advanced Concrete Technology","volume":"16 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136227639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper explores the effects of rebar as an internal restraint on the expansion of delayed ettringite formation (DEF) in concrete. Concrete specimens embedded with steel bars without end plates are subjected to heat treatment followed by immersion in water. The effect of stirrups on expansion is also investigated. The results show that the longitudinal expansion of specimens without stirrups differs depending on the longitudinal position, owing to the different degrees of restraint resulting from stress in the steel bar. The final transverse expansions of the specimens without stirrups are close to those measured for stress-free specimens. Conversely, longitudinal and transverse expansions are significantly reduced in the specimens with stirrups. This indicates that the combination of a longitudinal steel bar and stirrups induces three-dimensional confinement stresses that help to limit DEF expansion in both the longitudinal and transverse directions. Furthermore, possible debonding along the longitudinal bar is observed in specimens without stirrups when the transverse expansion of the prismatic specimens is 0.4 to 0.6%. This behavior is not observed in the specimens with stirrups, which demonstrates the effectiveness of three-dimensional restraints in significantly mitigating the risk of debonding, as well as DEF expansion.
{"title":"Influence of Reinforcing Rebar on Expansion due to Delayed Ettringite Formation along the Bonding Length – Part I: The Role of Bond on Expansive Behavior of Concrete","authors":"Yuichiro Kawabata, Taito Miura, Misato Fujishima, Naoshi Ueda, Yuya Takahashi, Shingo Asamoto, Stéphane Multon, Renaud-Pierre Martin, Jean-Francois Seignol","doi":"10.3151/jact.21.851","DOIUrl":"https://doi.org/10.3151/jact.21.851","url":null,"abstract":"This paper explores the effects of rebar as an internal restraint on the expansion of delayed ettringite formation (DEF) in concrete. Concrete specimens embedded with steel bars without end plates are subjected to heat treatment followed by immersion in water. The effect of stirrups on expansion is also investigated. The results show that the longitudinal expansion of specimens without stirrups differs depending on the longitudinal position, owing to the different degrees of restraint resulting from stress in the steel bar. The final transverse expansions of the specimens without stirrups are close to those measured for stress-free specimens. Conversely, longitudinal and transverse expansions are significantly reduced in the specimens with stirrups. This indicates that the combination of a longitudinal steel bar and stirrups induces three-dimensional confinement stresses that help to limit DEF expansion in both the longitudinal and transverse directions. Furthermore, possible debonding along the longitudinal bar is observed in specimens without stirrups when the transverse expansion of the prismatic specimens is 0.4 to 0.6%. This behavior is not observed in the specimens with stirrups, which demonstrates the effectiveness of three-dimensional restraints in significantly mitigating the risk of debonding, as well as DEF expansion.","PeriodicalId":14868,"journal":{"name":"Journal of Advanced Concrete Technology","volume":" 33","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135192268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Most waste disposal methods in Taiwan involve incineration, the incineration bottom ash (IBA) which is accumulated over the years and needs urgent treatment. Hence, using IBA to create renewable materials is essential for the sustainable development. In this study, natural aggregates in the controlled low strength material (CLSM) were replaced with IBA. Its workability, setting time, unit weight, mechanical behavior, and environmental impact were examined. The study also looked at the characteristics of CLSM and suggested solutions for improvement. The results showed that the substitution of natural fine aggregates with IBA had the most significant impact on the engineering properties of CLSM. IBA significantly improves the workability and reduces the unit weight of CLSM, but the presence of CaSO4 had a detrimental effect on its setting time and mechanical behavior. However, treating IBA at 750℃ before use significantly improved the mechanical properties of IBA-CLSM and shortened its setting time, making it a potential permanent backfill structure. The toxicity test results showed that the IBA-CLSM produced had no threat to environmental safety. The study proved that using IBA produced in Taiwan to replace natural aggregates in CLSM was feasible and an effective way to utilize IBA.
{"title":"Incineration Bottom Ash as Aggregate for Controlled Low Strength Materials: Implications and Coping Strategies","authors":"Wei-Chien Wang, Jia-Chen Xue, Chia-Yun Huang, Hsiao-Chuan Chang","doi":"10.3151/jact.21.837","DOIUrl":"https://doi.org/10.3151/jact.21.837","url":null,"abstract":"Most waste disposal methods in Taiwan involve incineration, the incineration bottom ash (IBA) which is accumulated over the years and needs urgent treatment. Hence, using IBA to create renewable materials is essential for the sustainable development. In this study, natural aggregates in the controlled low strength material (CLSM) were replaced with IBA. Its workability, setting time, unit weight, mechanical behavior, and environmental impact were examined. The study also looked at the characteristics of CLSM and suggested solutions for improvement. The results showed that the substitution of natural fine aggregates with IBA had the most significant impact on the engineering properties of CLSM. IBA significantly improves the workability and reduces the unit weight of CLSM, but the presence of CaSO4 had a detrimental effect on its setting time and mechanical behavior. However, treating IBA at 750℃ before use significantly improved the mechanical properties of IBA-CLSM and shortened its setting time, making it a potential permanent backfill structure. The toxicity test results showed that the IBA-CLSM produced had no threat to environmental safety. The study proved that using IBA produced in Taiwan to replace natural aggregates in CLSM was feasible and an effective way to utilize IBA.","PeriodicalId":14868,"journal":{"name":"Journal of Advanced Concrete Technology","volume":"3 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135431509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
José Granja, Renan Rocha Ribeiro, Thomas Russo, Rodrigo Lameiras, Miguel Azenha
The influence of temperature on the hydration of cementitious materials has been traditionally modelled using the maturity concept and Arrhenius law. This approach yields a single material property, called apparent activation energy (Ea), that describes the whole temperature dependence. Determining Ea experimentally has sparked controversy, such as whether the different properties (e.g., compressive strength, tensile strength, E-modulus) exhibit different Ea, whether a single Ea value exists for the entire hydration process, or whether cement paste and concrete possess the same Ea. Furthermore, studies measuring Ea from elastic modulus measurements are truly scarce, likely due to experimental challenges with measuring this property at early-ages. This work investigated the influence of temperature on the elastic modulus evolution of cement paste and concrete. A single mix for each material was tested with the EMM-ARM (Elasticity Modulus Measurement through Ambient Response Method) methodology under three different isothermal conditions. The resulting elastic modulus evolution curves were used to derive Ea evolution curves from two traditional computation methods: the ‘speed’ method and the ‘derivative of speed’ method. Results showed that the elastic modulus evolution of both materials initially presented a constant Ea, independent of temperature and hydration development as preconized by the classical Arrhenius law. However, as hydration progressed to later stages, the activation energy exhibited evident dependencies on both temperature and hydration levels. Cement paste and concrete consistently exhibited different Ea values throughout hydration, with concrete having higher values. The use of the Ea curves to superimpose the different experimental elastic modulus evolution curves by means of the equivalent age concept led to near-perfect superpositions, strengthening the validity of this concept when applied to elastic modulus evolution.
{"title":"Influence of Temperature in the Early-age Elastic Modulus Evolution of Cement Pastes and Concrete","authors":"José Granja, Renan Rocha Ribeiro, Thomas Russo, Rodrigo Lameiras, Miguel Azenha","doi":"10.3151/jact.21.803","DOIUrl":"https://doi.org/10.3151/jact.21.803","url":null,"abstract":"The influence of temperature on the hydration of cementitious materials has been traditionally modelled using the maturity concept and Arrhenius law. This approach yields a single material property, called apparent activation energy (Ea), that describes the whole temperature dependence. Determining Ea experimentally has sparked controversy, such as whether the different properties (e.g., compressive strength, tensile strength, E-modulus) exhibit different Ea, whether a single Ea value exists for the entire hydration process, or whether cement paste and concrete possess the same Ea. Furthermore, studies measuring Ea from elastic modulus measurements are truly scarce, likely due to experimental challenges with measuring this property at early-ages. This work investigated the influence of temperature on the elastic modulus evolution of cement paste and concrete. A single mix for each material was tested with the EMM-ARM (Elasticity Modulus Measurement through Ambient Response Method) methodology under three different isothermal conditions. The resulting elastic modulus evolution curves were used to derive Ea evolution curves from two traditional computation methods: the ‘speed’ method and the ‘derivative of speed’ method. Results showed that the elastic modulus evolution of both materials initially presented a constant Ea, independent of temperature and hydration development as preconized by the classical Arrhenius law. However, as hydration progressed to later stages, the activation energy exhibited evident dependencies on both temperature and hydration levels. Cement paste and concrete consistently exhibited different Ea values throughout hydration, with concrete having higher values. The use of the Ea curves to superimpose the different experimental elastic modulus evolution curves by means of the equivalent age concept led to near-perfect superpositions, strengthening the validity of this concept when applied to elastic modulus evolution.","PeriodicalId":14868,"journal":{"name":"Journal of Advanced Concrete Technology","volume":"11 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136377045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, CO2 quantification was performed on various concrete binder and aggregates by back titration, ther-mogravimetric method, and combustion-infrared absorption method, and their mutual consistency and error factors due to material characteristics were investigated. The back titration measures CO2 directly and is considered the suitable method for both materials, although the effect of sulfide was a concern. On the other hand, the TGA method was revealed to have the possibility of underestimating or overestimating the CO2 determination because the oxidation of sulfides in blast furnace slag, combustion of unburned carbon in fly ash, and dehydration of clay minerals in aggregate overlapping with the temperature range of calcination of calcium carbonate. In the combustion-infrared absorption method, elemental or organic carbon encapsulated in aggregate particles may underestimate or overestimate the CO2 content. In blended cement, sulfur compounds may interfere with the infrared absorption of CO2 and overestimate the amount of CO2. Based on these results, back titration was considered the most suitable method for determining CO2 for concrete materials. It is essential to understand the characteristics of each sample contained and select appropriate methods for CO2 quantification of concrete materials and concrete.
{"title":"Error Factors in Quantifying Inorganic Carbonate CO<sub>2</sub> in Concrete Materials","authors":"Haruka Takahashi, Ippei Maruyama, Takahiro Ohkubo, Ryoma Kitagaki, Yuya Suda, Atsushi Teramoto, Kazuko Haga, Takahiro Nagase","doi":"10.3151/jact.21.789","DOIUrl":"https://doi.org/10.3151/jact.21.789","url":null,"abstract":"In this study, CO2 quantification was performed on various concrete binder and aggregates by back titration, ther-mogravimetric method, and combustion-infrared absorption method, and their mutual consistency and error factors due to material characteristics were investigated. The back titration measures CO2 directly and is considered the suitable method for both materials, although the effect of sulfide was a concern. On the other hand, the TGA method was revealed to have the possibility of underestimating or overestimating the CO2 determination because the oxidation of sulfides in blast furnace slag, combustion of unburned carbon in fly ash, and dehydration of clay minerals in aggregate overlapping with the temperature range of calcination of calcium carbonate. In the combustion-infrared absorption method, elemental or organic carbon encapsulated in aggregate particles may underestimate or overestimate the CO2 content. In blended cement, sulfur compounds may interfere with the infrared absorption of CO2 and overestimate the amount of CO2. Based on these results, back titration was considered the most suitable method for determining CO2 for concrete materials. It is essential to understand the characteristics of each sample contained and select appropriate methods for CO2 quantification of concrete materials and concrete.","PeriodicalId":14868,"journal":{"name":"Journal of Advanced Concrete Technology","volume":"13 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135510699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aims to develop a simple yet accurate adaptive homogenization approach for modeling the effective elastic properties of concrete for the whole hydration range from early age to hardened state. Considering available data from a similar microstructure, the method accurately accounts for the impact of cement hydration degree on the effective elastic properties of the heterogeneous concrete mixture. The simulation results have been validated against experimental data and demonstrate exceptional agreement. Also, we have detailly discussed the role of water and the effect of the destructive and non-destructive measurement methods. The model’s simplicity and accuracy make it highly applicable in practical engineering scenarios.
{"title":"An Adaptive Homogenization Scheme for Modeling the Effective Elastic Properties of Early Age Concrete","authors":"Tuan Nguyen-Sy, Minh-Quan Thai, Ngoc-Minh Vu","doi":"10.3151/jact.21.777","DOIUrl":"https://doi.org/10.3151/jact.21.777","url":null,"abstract":"This study aims to develop a simple yet accurate adaptive homogenization approach for modeling the effective elastic properties of concrete for the whole hydration range from early age to hardened state. Considering available data from a similar microstructure, the method accurately accounts for the impact of cement hydration degree on the effective elastic properties of the heterogeneous concrete mixture. The simulation results have been validated against experimental data and demonstrate exceptional agreement. Also, we have detailly discussed the role of water and the effect of the destructive and non-destructive measurement methods. The model’s simplicity and accuracy make it highly applicable in practical engineering scenarios.","PeriodicalId":14868,"journal":{"name":"Journal of Advanced Concrete Technology","volume":"225 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136264029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuxuan Zhou, Qing Wang, Mianheng Lai, Johnny Ching Ming Ho
The use of engineered cementitious composite with polyvinyl alcohol fiber has shown excellent potential in building facilities due to its strain-hardening and multiple-cracking features. However, when polyvinyl alcohol fiber melts at around 230°C, spalling behavior of engineered cementitious composite may occur, weakening the mechanical properties and reducing ductility of high strength engineered cementitious composite. Thus, investigating the fire resistance is of great significance. By adding steel fibers to cementitious composites, qualitative and quantitative comparisons were done through observing appearance changes, spalling extent, surface cracking, mass loss, and residual mechanical properties. Results indicate that steel fiber can increase the risk of spalling and surface cracking in high strength engineered cementitious composite, improve residual mechanical abilities also. The ductility varies with steel fiber content at different elevated temperatures. Scanning electron microscopy results show that more hydration products are produced on the surface of steel fiber at 400°C, which improves interface transition zones between fiber and cementitious materials. However, an oxidation film found on the surface of steel fiber at 800°C triggers negative effect on bridging.
{"title":"Steel Fiber to Improve Thermal Resistance of High Strength PVA-ECC after Exposure to Elevated Temperature","authors":"Yuxuan Zhou, Qing Wang, Mianheng Lai, Johnny Ching Ming Ho","doi":"10.3151/jact.21.748","DOIUrl":"https://doi.org/10.3151/jact.21.748","url":null,"abstract":"The use of engineered cementitious composite with polyvinyl alcohol fiber has shown excellent potential in building facilities due to its strain-hardening and multiple-cracking features. However, when polyvinyl alcohol fiber melts at around 230°C, spalling behavior of engineered cementitious composite may occur, weakening the mechanical properties and reducing ductility of high strength engineered cementitious composite. Thus, investigating the fire resistance is of great significance. By adding steel fibers to cementitious composites, qualitative and quantitative comparisons were done through observing appearance changes, spalling extent, surface cracking, mass loss, and residual mechanical properties. Results indicate that steel fiber can increase the risk of spalling and surface cracking in high strength engineered cementitious composite, improve residual mechanical abilities also. The ductility varies with steel fiber content at different elevated temperatures. Scanning electron microscopy results show that more hydration products are produced on the surface of steel fiber at 400°C, which improves interface transition zones between fiber and cementitious materials. However, an oxidation film found on the surface of steel fiber at 800°C triggers negative effect on bridging.","PeriodicalId":14868,"journal":{"name":"Journal of Advanced Concrete Technology","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136265917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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