With the characteristics of low carbon, environmental protection, energy saving, and emission reduction, geopolymer pastes can effectively alleviate environmental and economic problems caused by the construction materials industry. The mechanical properties of geopolymer pastes are greatly affected by the composition of alkaline activators, while the existing research on their influence rules is not uniform. This study investigated the effects of alkaline activators composed of varying concentrations of NaOH solution under standard curing conditions on the mechanical properties and material characteristics of fly ash and slag-based geopolymer pastes. The results of the study indicated that under standard curing conditions, the mechanical properties of geopolymer pastes increased with the increase of NaOH solution concentration in alkaline activators. Under the influence of alkaline activators with 16 M NaOH solution, the flexural strength and compressive strength of geopolymer pastes reached the highest values at 28 d, up to 5.43 MPa and 39.13 MPa, respectively. Increasing the NaOH solution concentration in alkaline activators can promote the production of gel products such as N-A-S-H, forming a dense microstructure with a lower porosity, leading to higher mechanical properties.
{"title":"Performance of geopolymer paste under the different NaOH solution concentrations","authors":"Tao Wang, Xiangqian Fan, Changsheng Gao, Chiyu Qu","doi":"10.1680/jmacr.24.00069","DOIUrl":"https://doi.org/10.1680/jmacr.24.00069","url":null,"abstract":"With the characteristics of low carbon, environmental protection, energy saving, and emission reduction, geopolymer pastes can effectively alleviate environmental and economic problems caused by the construction materials industry. The mechanical properties of geopolymer pastes are greatly affected by the composition of alkaline activators, while the existing research on their influence rules is not uniform. This study investigated the effects of alkaline activators composed of varying concentrations of NaOH solution under standard curing conditions on the mechanical properties and material characteristics of fly ash and slag-based geopolymer pastes. The results of the study indicated that under standard curing conditions, the mechanical properties of geopolymer pastes increased with the increase of NaOH solution concentration in alkaline activators. Under the influence of alkaline activators with 16 M NaOH solution, the flexural strength and compressive strength of geopolymer pastes reached the highest values at 28 d, up to 5.43 MPa and 39.13 MPa, respectively. Increasing the NaOH solution concentration in alkaline activators can promote the production of gel products such as N-A-S-H, forming a dense microstructure with a lower porosity, leading to higher mechanical properties.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141664024","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 deals with the proposal of a model that can predict heat of hydration of concrete containing fly ash and the adiabatic temperature rise test results that are the basis of the model. For the adiabatic temperature rise tests, total of twelve concrete mixtures were prepared with variables of the percentage of fly ash replacement and w/cm. The test results indicate that the replacement of fly ash significantly reduces the adiabatic temperature rise and delays the early hydration of fly-ash blended cements. Additionally, w/cm was found to influence not only the maximum adiabatic temperature rise but also the slope of the temperature rise. Therefore, a regression analysis was conducted to propose three parameters (hydration time parameter, hydration slope parameter, ultimate degree of hydration) for the heat of hydration model of concrete containing fly ash. The developed heat of hydration model was validated using test data. Models that did not consider w/cm, similar to those proposed by other researchers, failed to accurately predict the test results. However, the final model developed, which incorporates w/cm, accurately predicted the test results, as confirmed through this study.
{"title":"Prediction of the heat of hydration of fly ash concrete by adiabatic temperature rise test and regression analysis","authors":"Hyun-Do Yun, W. Park, Y. Jang, Sun-Woo Kim","doi":"10.1680/jmacr.24.00002","DOIUrl":"https://doi.org/10.1680/jmacr.24.00002","url":null,"abstract":"This paper deals with the proposal of a model that can predict heat of hydration of concrete containing fly ash and the adiabatic temperature rise test results that are the basis of the model. For the adiabatic temperature rise tests, total of twelve concrete mixtures were prepared with variables of the percentage of fly ash replacement and w/cm. The test results indicate that the replacement of fly ash significantly reduces the adiabatic temperature rise and delays the early hydration of fly-ash blended cements. Additionally, w/cm was found to influence not only the maximum adiabatic temperature rise but also the slope of the temperature rise. Therefore, a regression analysis was conducted to propose three parameters (hydration time parameter, hydration slope parameter, ultimate degree of hydration) for the heat of hydration model of concrete containing fly ash. The developed heat of hydration model was validated using test data. Models that did not consider w/cm, similar to those proposed by other researchers, failed to accurately predict the test results. However, the final model developed, which incorporates w/cm, accurately predicted the test results, as confirmed through this study.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141700746","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}
Free chloride concentration distribution is important for assessing the corrosion risk of steel bars in reinforced concrete structures under chloride environment. In this study, a group of 3150 free chloride concentration data sets were obtained. Afterwards, three machine learning methods, including Support Vector Regression (SVR), Multilayer Perceptron (MLP) and One-Dimensional Convolutional Neural Network (1D-CNN) were adopted to construct models to predict chloride concentration distribution. Results show that 1D-CNN and MLP models are better at predicting the chloride concentration in fly ash concrete, whereas the prediction capability of SVR is relatively poor. Moreover, free chloride concentration prediction based on unmeasured parameters was conducted. Results show that the 1D-CNN and MLP models both have high prediction abilities, i.e., predicted results are consistent with experimental measurements, performing generally better than the time-varying model constructed based on Fick's second law. When the free chloride concentrations were higher than 0.1%, the SVR model had a better prediction effect, but had an unsatisfactory result and differed significantly from the actual chloride concentration when at a lower concentration. Overall, the 1D-CNN model performs the best in predicting free chloride concentrations of concrete at different penetration depths, exposure time and with different FA content.
{"title":"Prediction of free chloride concentration in fly ash concrete by machine learning methods SVR, MLP and CNN","authors":"Yurong Zhang, Tingfeng Zhu, Weilong Yu, Chuanqing Fu, Xingjian Liu, Lin Wan-Wendner","doi":"10.1680/jmacr.23.00293","DOIUrl":"https://doi.org/10.1680/jmacr.23.00293","url":null,"abstract":"Free chloride concentration distribution is important for assessing the corrosion risk of steel bars in reinforced concrete structures under chloride environment. In this study, a group of 3150 free chloride concentration data sets were obtained. Afterwards, three machine learning methods, including Support Vector Regression (SVR), Multilayer Perceptron (MLP) and One-Dimensional Convolutional Neural Network (1D-CNN) were adopted to construct models to predict chloride concentration distribution. Results show that 1D-CNN and MLP models are better at predicting the chloride concentration in fly ash concrete, whereas the prediction capability of SVR is relatively poor. Moreover, free chloride concentration prediction based on unmeasured parameters was conducted. Results show that the 1D-CNN and MLP models both have high prediction abilities, i.e., predicted results are consistent with experimental measurements, performing generally better than the time-varying model constructed based on Fick's second law. When the free chloride concentrations were higher than 0.1%, the SVR model had a better prediction effect, but had an unsatisfactory result and differed significantly from the actual chloride concentration when at a lower concentration. Overall, the 1D-CNN model performs the best in predicting free chloride concentrations of concrete at different penetration depths, exposure time and with different FA content.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141348157","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}
Z.C. Huang, B.X. Zhang, J.C.M. Ho, F. Ren, M.H. Lai
Heavy-weight concrete (HWC) is one of the most widely adopted radiation shielding material in the nuclear industry. In this study, two kinds of high-density aggregate, i.e., iron sand (IS) and steel slag coarse aggregate (SSCA), were adopted to fully replace river sand and natural coarse aggregate, respectively to make ultra-heavy-weight concrete (UHWC) with unit weight of more than 3800kg/m3 to ensure excellent radiation shielding performance. However, the use of IS and SSCA impaired the passing ability of UHWC seriously as the cement paste could not hold the IS and SSCA as firmly as natural aggregates owing to their high-density. To overcome this issue, the rheology of UHWC should be optimized, which could be achieved by replacing the cement with superfine silica fume (SSF) partially and using suitable amount of superplasticizer (SP) simultaneously to enhance the wet packing density (WPD) of UHWC. A total of 28 UHWC mixes with different replacement ratios of SSF (0%, 5%, 10% and 15%) and different dosages of SP were designed and the segregation width, flowability, L-box passing ability, unit weight and WPD were tested. Results revealed that incorporating an appropriate quantity of SSF and SP improved the WPD of UHWC, resulting in improved resistance to segregation, enhanced flowability, increased passing ability and a higher unit weight. Lastly, there exists a positive correlation between the flowability, passing ability and WPD of UHWC.
{"title":"Improving the passing ability of SSCA-IS ultra-heavy-weight concrete by optimizing its packing structure","authors":"Z.C. Huang, B.X. Zhang, J.C.M. Ho, F. Ren, M.H. Lai","doi":"10.1680/jmacr.24.00143","DOIUrl":"https://doi.org/10.1680/jmacr.24.00143","url":null,"abstract":"Heavy-weight concrete (HWC) is one of the most widely adopted radiation shielding material in the nuclear industry. In this study, two kinds of high-density aggregate, i.e., iron sand (IS) and steel slag coarse aggregate (SSCA), were adopted to fully replace river sand and natural coarse aggregate, respectively to make ultra-heavy-weight concrete (UHWC) with unit weight of more than 3800kg/m3 to ensure excellent radiation shielding performance. However, the use of IS and SSCA impaired the passing ability of UHWC seriously as the cement paste could not hold the IS and SSCA as firmly as natural aggregates owing to their high-density. To overcome this issue, the rheology of UHWC should be optimized, which could be achieved by replacing the cement with superfine silica fume (SSF) partially and using suitable amount of superplasticizer (SP) simultaneously to enhance the wet packing density (WPD) of UHWC. A total of 28 UHWC mixes with different replacement ratios of SSF (0%, 5%, 10% and 15%) and different dosages of SP were designed and the segregation width, flowability, L-box passing ability, unit weight and WPD were tested. Results revealed that incorporating an appropriate quantity of SSF and SP improved the WPD of UHWC, resulting in improved resistance to segregation, enhanced flowability, increased passing ability and a higher unit weight. Lastly, there exists a positive correlation between the flowability, passing ability and WPD of UHWC.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141364686","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 present study investigated the synergistic influence of bottom ash as a Portland cement (PC) and natural fine aggregate (NFA) replacement in concrete. Coal bottom ash (CBA) is a heavy ash that settles at bottom of combustion chamber of a thermal power plant and was grinded (GCBA) for two hours prior to replacing 10-30% PC whereas CBA was used in raw form to replace 25% and 50% NFA. The mechanical properties along with durability properties (accelerated carbonation and chloride penetration) were studied after 28 day and 90 days curing. Non-destructive tests were also performed to check the quality of CBA based concrete. Microstructural characterization was conducted using various techniques like XRD, SEM and FTIR. The concrete with 20% GCBA and 25% CBA (G20C25) reported best performance in terms of parameters studied owing to pozzolanic reactivity of GCBA and filler effect of fine CBA. The microstructural investigations also validated the findings and trends observed of experimental results. Well fitted mathematical models were derived and optimisation was carried out using desirability function approach. Multi-objective optimization recommended 21.80% GCBA and 24.17% CBA as the optimum amount resulting in significant reduction of 19.19% and 18.19% in carbon footprints and eco-costs compared to control mix.
{"title":"Valorization of bottom ash in concrete: serviceability, microstructural and sustainability characterization","authors":"Nitin Ankur, Navdeep Singh","doi":"10.1680/jmacr.23.00313","DOIUrl":"https://doi.org/10.1680/jmacr.23.00313","url":null,"abstract":"The present study investigated the synergistic influence of bottom ash as a Portland cement (PC) and natural fine aggregate (NFA) replacement in concrete. Coal bottom ash (CBA) is a heavy ash that settles at bottom of combustion chamber of a thermal power plant and was grinded (GCBA) for two hours prior to replacing 10-30% PC whereas CBA was used in raw form to replace 25% and 50% NFA. The mechanical properties along with durability properties (accelerated carbonation and chloride penetration) were studied after 28 day and 90 days curing. Non-destructive tests were also performed to check the quality of CBA based concrete. Microstructural characterization was conducted using various techniques like XRD, SEM and FTIR. The concrete with 20% GCBA and 25% CBA (G20C25) reported best performance in terms of parameters studied owing to pozzolanic reactivity of GCBA and filler effect of fine CBA. The microstructural investigations also validated the findings and trends observed of experimental results. Well fitted mathematical models were derived and optimisation was carried out using desirability function approach. Multi-objective optimization recommended 21.80% GCBA and 24.17% CBA as the optimum amount resulting in significant reduction of 19.19% and 18.19% in carbon footprints and eco-costs compared to control mix.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141362229","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}
Corrosion of steel in steel-reinforced concrete is one of the main factors limiting the durability of existing reinforced concrete components. Based on the corrosive circumstance, there are different methods of prevention and repair which can be applied to the concrete. In case of carbonation-initiated corrosion, the chemical realkalization is one of the standard measures to counteract the alteration processes in the concrete which lead to corrosion of the reinforcement. This review paper summarizes the current state of research on carbonated concrete chemical realkalization with regard to the various materials that have been investigated over time for their applicability to this repair measure. This review summarizes current research results in the field of carbonated concrete and the proven pozzolanic reactivity of the carbonation products in contact with portlandite which suggests an inhibitory effect on chemical realkalization, although the influence of this has not yet been investigated. Further, there are initial approaches that deviate from the application of a classic Portland cement as a repair material, but their applicability in practice must be questioned. The use of alternative binders and the associated different composition of the pore solution and the varying alkalinity of these binders, such as composite cements with a high substitution rate or alkaline-activated binders, have not yet been brought into connection with repair processes such as chemical realkalization, although the chemical composition of the binders is of the greatest importance for a successful application of the repair measure.
{"title":"Review of basics and new opportunities for the chemical realkalization of carbonated concrete including the application of alkali-activated materials","authors":"Clarissa Glawe, M. Raupach","doi":"10.1680/jmacr.24.00026","DOIUrl":"https://doi.org/10.1680/jmacr.24.00026","url":null,"abstract":"Corrosion of steel in steel-reinforced concrete is one of the main factors limiting the durability of existing reinforced concrete components. Based on the corrosive circumstance, there are different methods of prevention and repair which can be applied to the concrete. In case of carbonation-initiated corrosion, the chemical realkalization is one of the standard measures to counteract the alteration processes in the concrete which lead to corrosion of the reinforcement. This review paper summarizes the current state of research on carbonated concrete chemical realkalization with regard to the various materials that have been investigated over time for their applicability to this repair measure. This review summarizes current research results in the field of carbonated concrete and the proven pozzolanic reactivity of the carbonation products in contact with portlandite which suggests an inhibitory effect on chemical realkalization, although the influence of this has not yet been investigated. Further, there are initial approaches that deviate from the application of a classic Portland cement as a repair material, but their applicability in practice must be questioned. The use of alternative binders and the associated different composition of the pore solution and the varying alkalinity of these binders, such as composite cements with a high substitution rate or alkaline-activated binders, have not yet been brought into connection with repair processes such as chemical realkalization, although the chemical composition of the binders is of the greatest importance for a successful application of the repair measure.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141366260","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}
Alkali activated materials are regarded as a substitution building material of Portland Cement (PC) with high chloride resistance and low CO2 footprint. This review study provides a multi-scale perspective to understand material-product-microstructure-property relationships in terms of chloride binding behavior of AAMs. Physical and chemical chloride stability of different reaction products is summarized from nanostructure, microstructure to macro properties. The analysis of cited studies are determined to give an overview of recent progress in chloride transport in AAMs influenced by different reaction products. Results show that higher Ca/Si, Al/Si molar and alkali content increase amorphous phases formation, leading to a denser microstructure and lower chloride penetration in AAMs. Higher MgO and Al2O3 incorporation results in more formation of hydrotalcite. The enhanced physical and chemical absorption of chloride by hydrotalcite leads to higher resistance of chloride penetration in AAMs. The investigation of increasing chloride resistance can potentially focus on the increase of gels and hydrotalcite formation.
{"title":"Chloride transport in alkali activated materials influenced by different reaction products: a review","authors":"Tao Liu, Jianfeng Fan, Ziqiang Peng","doi":"10.1680/jmacr.23.00285","DOIUrl":"https://doi.org/10.1680/jmacr.23.00285","url":null,"abstract":"Alkali activated materials are regarded as a substitution building material of Portland Cement (PC) with high chloride resistance and low CO2 footprint. This review study provides a multi-scale perspective to understand material-product-microstructure-property relationships in terms of chloride binding behavior of AAMs. Physical and chemical chloride stability of different reaction products is summarized from nanostructure, microstructure to macro properties. The analysis of cited studies are determined to give an overview of recent progress in chloride transport in AAMs influenced by different reaction products. Results show that higher Ca/Si, Al/Si molar and alkali content increase amorphous phases formation, leading to a denser microstructure and lower chloride penetration in AAMs. Higher MgO and Al2O3 incorporation results in more formation of hydrotalcite. The enhanced physical and chemical absorption of chloride by hydrotalcite leads to higher resistance of chloride penetration in AAMs. The investigation of increasing chloride resistance can potentially focus on the increase of gels and hydrotalcite formation.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141267714","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}
Lightweight geopolymer can combine good physical and mechanical properties, good thermal and chemical stability, low CO2 emission and low energy. The development of high strength lightweight geopolymer concrete for load-bearing structures is important to expand the application range of geopolymer. This paper presents an improvement study on the mechanical properties and pore structure of lightweight geopolymer concrete (LGC) by adding ground granulated blast-furnace slag (GGBFS). The effect of GGBFS content on the mechanical properties of LGC was analyzed, including ultimate compressive stress and elastic modulus. The variation in the microscopic pore structure of LGC with different GGBFS content was further analyzed by low-field nuclear magnetic resonance (LF-NMR) technology. The lightweight geopolymer concrete with different strength grades was proposed including LC20, LC30 and LC40. The results show that as the GGBFS content increases, the ultimate compressive stress and specific strength of LGC increase while the strain corresponding to peak stress decreases, which means that the mechanical properties and deformation resistance of LGC are improved. The CO2 emissions of LGC are lower than that of cement-based lightweight concrete, which shows good sustainability. The results also show that the addition of GGBFS can produce more gel and reduce the volume proportion of capillary pores and air pores, resulting in the densification of the LGC. The recommended GGBFS contents corresponding to the strength grades of LC20, LC30 and LC40 are 0 ∼ 12.7 %, 12.7 % ∼ 24.6 % and 24.6 % ∼ 30%, respectively. The LGC has the characteristics of lightweight and high-strength, which has a potential application in civil engineering. Highlights [1] Mechanical properties and pore structure of LGC were improved by adding GGBFS. [2] The effect of GGBFS content on geopolymer concrete properties was discussed. [3] Effect of slag content on pore structure of geopolymer concrete were studied. [4] GGBGS content of geopolymer concrete with different strength grades was proposed.
{"title":"Optimization of mechanical properties and pore structure of lightweight geopolymer concrete using GGBFS based on LF-NMR technology","authors":"W. Zhong, H. Wang, X. Zhao, J.X. Li, L.F. Fan","doi":"10.1680/jmacr.23.00295","DOIUrl":"https://doi.org/10.1680/jmacr.23.00295","url":null,"abstract":"Lightweight geopolymer can combine good physical and mechanical properties, good thermal and chemical stability, low CO2 emission and low energy. The development of high strength lightweight geopolymer concrete for load-bearing structures is important to expand the application range of geopolymer. This paper presents an improvement study on the mechanical properties and pore structure of lightweight geopolymer concrete (LGC) by adding ground granulated blast-furnace slag (GGBFS). The effect of GGBFS content on the mechanical properties of LGC was analyzed, including ultimate compressive stress and elastic modulus. The variation in the microscopic pore structure of LGC with different GGBFS content was further analyzed by low-field nuclear magnetic resonance (LF-NMR) technology. The lightweight geopolymer concrete with different strength grades was proposed including LC20, LC30 and LC40. The results show that as the GGBFS content increases, the ultimate compressive stress and specific strength of LGC increase while the strain corresponding to peak stress decreases, which means that the mechanical properties and deformation resistance of LGC are improved. The CO2 emissions of LGC are lower than that of cement-based lightweight concrete, which shows good sustainability. The results also show that the addition of GGBFS can produce more gel and reduce the volume proportion of capillary pores and air pores, resulting in the densification of the LGC. The recommended GGBFS contents corresponding to the strength grades of LC20, LC30 and LC40 are 0 ∼ 12.7 %, 12.7 % ∼ 24.6 % and 24.6 % ∼ 30%, respectively. The LGC has the characteristics of lightweight and high-strength, which has a potential application in civil engineering. Highlights [1] Mechanical properties and pore structure of LGC were improved by adding GGBFS. [2] The effect of GGBFS content on geopolymer concrete properties was discussed. [3] Effect of slag content on pore structure of geopolymer concrete were studied. [4] GGBGS content of geopolymer concrete with different strength grades was proposed.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141266963","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}
Engineered Cementitious Composites (ECC) have garnered significant attention within the construction industry due to their exceptional mechanical properties and durability. This thorough review presents a meticulous analysis of the progress and prospects in ECC research. It commences by introducing the background and rationale for investigating ECC, while outlining the objectives of the review. The review provides an encompassing overview of ECC, encompassing its definition, characteristics, historical development, composition, and constituent materials. Emphasis is placed on the examination of ECC‘s mechanical properties, specifically its flexural behaviour, tensile behaviour, compressive strength, and resistance to environmental factors. Furthermore, the rheological properties of ECC, including workability, flowability, self-healing, crack mitigation, viscosity, and thixotropy, are discussed in detail. The review delves into the influence of fibre reinforcement on ECC, encompassing the types of fibres utilised, their impact on mechanical and structural properties, as well as fibre dispersion and orientation. Additionally, it explores the diverse applications of ECC across various fields, such as structural applications and sustainable building practices. The challenges and limitations associated with ECC, such as cost and availability, are addressed, alongside an exploration of future trends and research directions.
{"title":"Advancements and perspectives in engineered cementitious composites (ECC): a comprehensive review","authors":"S. Barbhuiya, B. B. Das, Dibyendu Adak","doi":"10.1680/jmacr.24.00047","DOIUrl":"https://doi.org/10.1680/jmacr.24.00047","url":null,"abstract":"Engineered Cementitious Composites (ECC) have garnered significant attention within the construction industry due to their exceptional mechanical properties and durability. This thorough review presents a meticulous analysis of the progress and prospects in ECC research. It commences by introducing the background and rationale for investigating ECC, while outlining the objectives of the review. The review provides an encompassing overview of ECC, encompassing its definition, characteristics, historical development, composition, and constituent materials. Emphasis is placed on the examination of ECC‘s mechanical properties, specifically its flexural behaviour, tensile behaviour, compressive strength, and resistance to environmental factors. Furthermore, the rheological properties of ECC, including workability, flowability, self-healing, crack mitigation, viscosity, and thixotropy, are discussed in detail. The review delves into the influence of fibre reinforcement on ECC, encompassing the types of fibres utilised, their impact on mechanical and structural properties, as well as fibre dispersion and orientation. Additionally, it explores the diverse applications of ECC across various fields, such as structural applications and sustainable building practices. The challenges and limitations associated with ECC, such as cost and availability, are addressed, alongside an exploration of future trends and research directions.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":null,"pages":null},"PeriodicalIF":2.7,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140972496","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}
S. Ranjithkumar, M. Muthuraja, S. N. Khaderi, S. Suriya Prakash
Self-compacting concrete (SCC) is widely used in reinforced concrete (RC) buildings due to its ability to consolidate by weight and its lack of requirement for external vibration. RC buildings can be subjected to high strain rate loadings during the early days of construction or in their service life. Thus, it is critical to understand the behaviour of concrete under high strain rate loadings at different ages. Previous research shows that minimal studies have focused on the early-age behaviour of concrete under a high strain rate. This study tries to fill this knowledge gap. It focuses on the behaviour of M40 grade SCC under three levels of strain rate loading at the age of one, three, seven, 14 and 28 days. The Split-Hopkinson Pressure Bar (SHPB) setup is used to test the SCC specimens with a diameter of 100 mm and thickness of 50 mm under high strain rates. Forty-five specimens were tested at strain rates ranging from 30 s−1 to 110 s−1 at the age of one to 28 days. The compressive strength, peak strain and elastic modulus results from the SHPB experiment are compared with the quasi-static test results of SCC specimens. The dynamic increase factor (DIF) of the SCC specimens from the SHPB experiment is compared with the CEB – fib code model. The results indicate that the DIF reduces as the concrete's strength and age increase.
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