Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139146
Haoliang Dong , Huajian Li , Zhiqiang Yang , Henan Shi , Liangshun Li , Fali Huang , Zhen Wang , Zhonglai Yi
In certain extreme environments, the bearing capacity of concrete structures diminishes significantly as temperatures soar, simultaneously exposing them to a heightened risk of brittle cracking. The paper aims to elucidate the fracture toughness of waterborne polyurethane modified concrete (WPMC) at different temperatures. Furthermore, a predictive model for the fracture toughness of WPMC, which incorporates both temperature and the waterborne polyurethane (WP) content, is proposed. The flexural strength and fracture toughness of WPMC were tested separately at 20℃, 40℃, 60℃, and 80℃. Utilizing digital image correlation (DIC) technology, the bottom longitudinal strain of WPMC under flexural loading was analyzed. The impact of temperature and WP content on the energy absorption capacity and deformation behavior of WPMC exposed to extreme environment was also investigated. By introducing the microstructural parameters C and Cw to characterize the elastic and plastic deformations of WPMC before and after cracking, a prediction model between the microstructural parameters and temperature, WP content was established. This model enables the prediction of the fracture toughness KIC of WPMC at different temperatures by measuring Fmax.
{"title":"Prediction model for fracture toughness of waterborne polyurethane modified concrete at different temperatures","authors":"Haoliang Dong , Huajian Li , Zhiqiang Yang , Henan Shi , Liangshun Li , Fali Huang , Zhen Wang , Zhonglai Yi","doi":"10.1016/j.conbuildmat.2024.139146","DOIUrl":"10.1016/j.conbuildmat.2024.139146","url":null,"abstract":"<div><div>In certain extreme environments, the bearing capacity of concrete structures diminishes significantly as temperatures soar, simultaneously exposing them to a heightened risk of brittle cracking. The paper aims to elucidate the fracture toughness of waterborne polyurethane modified concrete (WPMC) at different temperatures. Furthermore, a predictive model for the fracture toughness of WPMC, which incorporates both temperature and the waterborne polyurethane (WP) content, is proposed. The flexural strength and fracture toughness of WPMC were tested separately at 20℃, 40℃, 60℃, and 80℃. Utilizing digital image correlation (DIC) technology, the bottom longitudinal strain of WPMC under flexural loading was analyzed. The impact of temperature and WP content on the energy absorption capacity and deformation behavior of WPMC exposed to extreme environment was also investigated. By introducing the microstructural parameters <em>C</em> and <em>C</em><sub>w</sub> to characterize the elastic and plastic deformations of WPMC before and after cracking, a prediction model between the microstructural parameters and temperature, WP content was established. This model enables the prediction of the fracture toughness <em>K</em><sub>IC</sub> of WPMC at different temperatures by measuring <em>F</em><sub>max</sub>.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139146"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139079
Zhongshao Yao , Mingli Li , Shibo Huang , Ming Chang , Zhibin Yang
The grouting reinforcement technology is an essential method to enhance the mechanical performance of fractured rock masses and the effectiveness of reinforcement varies with different grouting materials. To further understand the mechanical improvement capabilities of each grout and the reinforcement mechanisms at the grout-rock interface, this study prepared samples with different grouting materials (sulphoaluminate cement (SAC), ultra-fine cement (UFC), and epoxy resin (EPR)) and the uniaxial compression tests were conducted. Based on these tests, the macro and micro mechanical characteristics of different grouting samples were revealed using particle image velocimetry (PIV), acoustic emission (AE), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR). The results indicate that grouting helps improve the mechanical performance and deformation resistance of fractured rock masses. It effectively limited lateral displacement of the samples, reduced stress concentration at fracture tips, enhanced shear effects during sample fracture, and altered the crack propagation process and failure modes. Compared to the fractured samples, the peak strength of SAC, UFC, and EPR samples increased by 17.8 %, 23.4 %, and 28.3 %, and the elastic modulus increased by 14.3 %, 7.9 %, and 24.8 %, respectively. Among these, the EPR samples exhibited a similarity in parameter indicators to intact samples of over 85 %, making EPR the optimal grouting material. The degree of grout-rock fusion is the primary factor influencing grouting reinforcement effectiveness. SAC is covering-type cement, UFC is embedded cement, EPR is a fusion material, and the fusion-type materials are more beneficial for improving the mechanical performance of fractured rocks.
{"title":"Study on the impact of grouting reinforcement on the mechanical behavior of non-penetrating fracture sandstone","authors":"Zhongshao Yao , Mingli Li , Shibo Huang , Ming Chang , Zhibin Yang","doi":"10.1016/j.conbuildmat.2024.139079","DOIUrl":"10.1016/j.conbuildmat.2024.139079","url":null,"abstract":"<div><div>The grouting reinforcement technology is an essential method to enhance the mechanical performance of fractured rock masses and the effectiveness of reinforcement varies with different grouting materials. To further understand the mechanical improvement capabilities of each grout and the reinforcement mechanisms at the grout-rock interface, this study prepared samples with different grouting materials (sulphoaluminate cement (SAC), ultra-fine cement (UFC), and epoxy resin (EPR)) and the uniaxial compression tests were conducted. Based on these tests, the macro and micro mechanical characteristics of different grouting samples were revealed using particle image velocimetry (PIV), acoustic emission (AE), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR). The results indicate that grouting helps improve the mechanical performance and deformation resistance of fractured rock masses. It effectively limited lateral displacement of the samples, reduced stress concentration at fracture tips, enhanced shear effects during sample fracture, and altered the crack propagation process and failure modes. Compared to the fractured samples, the peak strength of SAC, UFC, and EPR samples increased by 17.8 %, 23.4 %, and 28.3 %, and the elastic modulus increased by 14.3 %, 7.9 %, and 24.8 %, respectively. Among these, the EPR samples exhibited a similarity in parameter indicators to intact samples of over 85 %, making EPR the optimal grouting material. The degree of grout-rock fusion is the primary factor influencing grouting reinforcement effectiveness. SAC is covering-type cement, UFC is embedded cement, EPR is a fusion material, and the fusion-type materials are more beneficial for improving the mechanical performance of fractured rocks.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139079"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139135
Li Wang , Wenyu Lin , Qian Wan , Zhijian Li , Gang Bai
Cementitious materials used in 3D printing exhibit significant time-dependent characteristics in terms of early-age rheology and stiffness development that limit high-quality manufacturing. However, the centimeter-level accuracy of concrete 3D printing makes satisfying engineering requirements difficult. To address these challenges, a hybrid additive–subtractive method was developed in this study to improve the accuracy of manufacturing concrete products. The printed components were subjected to a cutting/grinding subtractive treatment until their actual dimensions matched the design dimensions within acceptable tolerances. The processing error of the method was quantitatively analyzed using 3D laser-scanning technology, and the method’s effectiveness was validated by conducting various case studies. The results indicated that the manufacturing mismatch can be controlled within a range of 2 mm, and the surface roughness of the components can be reduced from 8.5 mm to 0.5 mm, resulting in a 94.12 % increase. Thus, the proposed method can be used in the high-precision construction of various free-form structures.
{"title":"Manufacturing accuracy improvement of concrete product by hybrid additive-subtractive method based on the time-dependent characteristics of cementitious materials","authors":"Li Wang , Wenyu Lin , Qian Wan , Zhijian Li , Gang Bai","doi":"10.1016/j.conbuildmat.2024.139135","DOIUrl":"10.1016/j.conbuildmat.2024.139135","url":null,"abstract":"<div><div>Cementitious materials used in 3D printing exhibit significant time-dependent characteristics in terms of early-age rheology and stiffness development that limit high-quality manufacturing. However, the centimeter-level accuracy of concrete 3D printing makes satisfying engineering requirements difficult. To address these challenges, a hybrid additive–subtractive method was developed in this study to improve the accuracy of manufacturing concrete products. The printed components were subjected to a cutting/grinding subtractive treatment until their actual dimensions matched the design dimensions within acceptable tolerances. The processing error of the method was quantitatively analyzed using 3D laser-scanning technology, and the method’s effectiveness was validated by conducting various case studies. The results indicated that the manufacturing mismatch can be controlled within a range of 2 mm, and the surface roughness of the components can be reduced from 8.5 mm to 0.5 mm, resulting in a 94.12 % increase. Thus, the proposed method can be used in the high-precision construction of various free-form structures.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139135"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The presence of cracks and pores in recycled aggregates exacerbates the susceptibility of recycled concrete to chloride ion penetration, thereby diminishing its durability. The incorporation of slag has shown promise in enhancing the chloride ion resistance of recycled concrete, although its mechanism under biaxial loading conditions remains unclear. In this study, a self-made apparatus was employed to investigate chloride ion diffusion in recycled concrete with slag content ranging from 0 % to 30 %, subjected to biaxial loading with stress ratios of 1:0, 1:1, and 2:1. To validate the reliability of the self-made device, both natural diffusion tests and standard rapid chloride ion migration (RCM) tests were conducted. All three approaches provided consistent evidence of a decrease in the chloride ion diffusion coefficient as the slag content increased. This phenomenon was attributed to the slag's capacity to fill large pores and interrupt interconnected cracks, as observed through SEM analysis, even though porosity increased. Under biaxial loading, the chloride ion diffusion coefficient of slag-recycled concrete exhibited an initial decrease followed by an increase as the stress level escalated. The lowest chloride ion diffusion coefficient for recycled concrete was achieved at a stress ratio of 1:1, a stress level of 0.5, and a slag content of 30 %. Furthermore, a predictive model for the chloride ion diffusion coefficient in slag concrete under biaxial loading conditions was developed.
{"title":"Chloride ion diffusion in recycled concrete containing slag under biaxial compression","authors":"Jingwei Ying , Wei Chen , Shuangren Chen , Baixi Chen","doi":"10.1016/j.conbuildmat.2024.139136","DOIUrl":"10.1016/j.conbuildmat.2024.139136","url":null,"abstract":"<div><div>The presence of cracks and pores in recycled aggregates exacerbates the susceptibility of recycled concrete to chloride ion penetration, thereby diminishing its durability. The incorporation of slag has shown promise in enhancing the chloride ion resistance of recycled concrete, although its mechanism under biaxial loading conditions remains unclear. In this study, a self-made apparatus was employed to investigate chloride ion diffusion in recycled concrete with slag content ranging from 0 % to 30 %, subjected to biaxial loading with stress ratios of 1:0, 1:1, and 2:1. To validate the reliability of the self-made device, both natural diffusion tests and standard rapid chloride ion migration (RCM) tests were conducted. All three approaches provided consistent evidence of a decrease in the chloride ion diffusion coefficient as the slag content increased. This phenomenon was attributed to the slag's capacity to fill large pores and interrupt interconnected cracks, as observed through SEM analysis, even though porosity increased. Under biaxial loading, the chloride ion diffusion coefficient of slag-recycled concrete exhibited an initial decrease followed by an increase as the stress level escalated. The lowest chloride ion diffusion coefficient for recycled concrete was achieved at a stress ratio of 1:1, a stress level of 0.5, and a slag content of 30 %. Furthermore, a predictive model for the chloride ion diffusion coefficient in slag concrete under biaxial loading conditions was developed.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"454 ","pages":"Article 139136"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139094
Jie Xu , Qiang Cao , Weixin Wang , Yihang Liu
The wedge-type anchorage system is widely used for CFRP tendon anchoring due to its convenient construction, compact size and high efficiency. However, stress concentration at the gap between wedges often causes transverse damage in CFRP tendons, which compromises the safety of CFRP cables. Presently, research on the transverse compression damage behavior of CFRP tendons caused by wedges remains limited to qualitative descriptions and lacks essential theoretical support. This study investigates the transverse mechanical properties and compression damage behavior of CFRP tendons. Prismatic specimen tests for transverse compression and shear were conducted to accurately determine the transverse mechanical properties of CFRP tendons. By conducting matching shaped compression tests on CFRP tendons, the influence of different wedge gaps on compression damage behavior was examined, and the compression damage mechanism caused by wedges was analyzed. Furthermore, the LaRC05 composite material failure criterion was utilized to predict the compression damage behavior of CFRP tendons. The results indicate that compression damage of CFRP tendons in wedge-type anchorage primarily occurs due to transverse shear cracks initiating at the edges of the gaps. These cracks propagate inward under compression load until the tendons collapse. The extent of compression damage is significantly influenced by the ratio of gap width to tendon diameter . Under the same loading conditions, the compression damage exacerbates with the increase of . Digital Image Correlation (DIC) analysis was used to determine the critical damage state under various values, and a linear relationship between the critical equivalent contact pressure () and was established. The LaRC05 composite material failure criterion accurately predicts the morphology of compression cracks and critical damage states of CFRP tendons. The research results of this paper provide crucial theoretical support for damage control and offer valuable guidance for the future design of anchorage systems.
{"title":"Study on the transverse compression damage behavior of CFRP tendons in the wedge-type anchorage system","authors":"Jie Xu , Qiang Cao , Weixin Wang , Yihang Liu","doi":"10.1016/j.conbuildmat.2024.139094","DOIUrl":"10.1016/j.conbuildmat.2024.139094","url":null,"abstract":"<div><div>The wedge-type anchorage system is widely used for CFRP tendon anchoring due to its convenient construction, compact size and high efficiency. However, stress concentration at the gap between wedges often causes transverse damage in CFRP tendons, which compromises the safety of CFRP cables. Presently, research on the transverse compression damage behavior of CFRP tendons caused by wedges remains limited to qualitative descriptions and lacks essential theoretical support. This study investigates the transverse mechanical properties and compression damage behavior of CFRP tendons. Prismatic specimen tests for transverse compression and shear were conducted to accurately determine the transverse mechanical properties of CFRP tendons. By conducting matching shaped compression tests on CFRP tendons, the influence of different wedge gaps on compression damage behavior was examined, and the compression damage mechanism caused by wedges was analyzed. Furthermore, the LaRC05 composite material failure criterion was utilized to predict the compression damage behavior of CFRP tendons. The results indicate that compression damage of CFRP tendons in wedge-type anchorage primarily occurs due to transverse shear cracks initiating at the edges of the gaps. These cracks propagate inward under compression load until the tendons collapse. The extent of compression damage is significantly influenced by the ratio of gap width to tendon diameter <span><math><mi>β</mi></math></span>. Under the same loading conditions, the compression damage exacerbates with the increase of <span><math><mi>β</mi></math></span>. Digital Image Correlation (DIC) analysis was used to determine the critical damage state under various <span><math><mi>β</mi></math></span> values, and a linear relationship between the critical equivalent contact pressure (<span><math><msub><mrow><mi>p</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>) and <span><math><mi>β</mi></math></span> was established. The LaRC05 composite material failure criterion accurately predicts the morphology of compression cracks and critical damage states of CFRP tendons. The research results of this paper provide crucial theoretical support for damage control and offer valuable guidance for the future design of anchorage systems.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"454 ","pages":"Article 139094"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139115
Amit Jain, Ghanshyam Pal
Application of encapsulated phase change materials (PCM) is becoming an attractive passive measure to develop energy efficient buildings. In the present work, the eutectic mixture of two saturated fatty acids (lauric acid and palmitic acid in 80:20 ratio, HTPCM) was selected and encapsulated in a novel multilayer architecture to develop PCM beads. The bead architecture includes a PCM core enveloped by thermally conductive calcium alginate (Ca-Alg) biopolymer + multiwall carbon nanotubes intermediate shell to promote heat transfer from the core and the outer rugged coating of flyash + water-based polyurethane (PU) to improve mechanical integrity and interlocking with wet cement mortar matrix during mix preparation. The thermal characteristics of four pure PCM (capric acid, lauric acid, myristic acid, and stearic acid) and one eutectic mixture (HTPCM) were measured using differential scanning calorimetry (DSC) to select the suitable PCM as per prevailing local ambient temperature. As per scanning electron microscopy (SEM) results, the average core size is in the range of 1.5 – 2.0 mm and PCM is stored in the bead core as tiny globules separated by Ca-Alg membrane. Single bead compression test performed on multilayer PCM (m-PCM) bead show that the shell of the bead possesses sufficient mechanical strength. The Fourier transformed infrared spectroscopy (FTIR) analysis and thermogravimetric analysis (TGA) studies confirm that the HTPCM and coating materials are chemically / thermally stable through different steps of fabrication and heating / cooling thermal cycles. Finally, the filter paper leakage test showed that the multilayer bead shell can prevent the PCM leakage from the core during bead heating. The various test results reported herein corroborate that the proposed architecture provides good physical properties and mechanical strength to the encapsulated PCM beads.
{"title":"Development and characterization of saturated fatty acids and biopolymer based novel multilayer encapsulated phase change materials system for buildings","authors":"Amit Jain, Ghanshyam Pal","doi":"10.1016/j.conbuildmat.2024.139115","DOIUrl":"10.1016/j.conbuildmat.2024.139115","url":null,"abstract":"<div><div>Application of encapsulated phase change materials (PCM) is becoming an attractive passive measure to develop energy efficient buildings. In the present work, the eutectic mixture of two saturated fatty acids (lauric acid and palmitic acid in 80:20 ratio, HTPCM) was selected and encapsulated in a novel multilayer architecture to develop PCM beads. The bead architecture includes a PCM core enveloped by thermally conductive calcium alginate (Ca-Alg) biopolymer + multiwall carbon nanotubes intermediate shell to promote heat transfer from the core and the outer rugged coating of flyash + water-based polyurethane (PU) to improve mechanical integrity and interlocking with wet cement mortar matrix during mix preparation. The thermal characteristics of four pure PCM (capric acid, lauric acid, myristic acid, and stearic acid) and one eutectic mixture (HTPCM) were measured using differential scanning calorimetry (DSC) to select the suitable PCM as per prevailing local ambient temperature. As per scanning electron microscopy (SEM) results, the average core size is in the range of 1.5 – 2.0 mm and PCM is stored in the bead core as tiny globules separated by Ca-Alg membrane. Single bead compression test performed on multilayer PCM (m-PCM) bead show that the shell of the bead possesses sufficient mechanical strength. The Fourier transformed infrared spectroscopy (FTIR) analysis and thermogravimetric analysis (TGA) studies confirm that the HTPCM and coating materials are chemically / thermally stable through different steps of fabrication and heating / cooling thermal cycles. Finally, the filter paper leakage test showed that the multilayer bead shell can prevent the PCM leakage from the core during bead heating. The various test results reported herein corroborate that the proposed architecture provides good physical properties and mechanical strength to the encapsulated PCM beads.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"454 ","pages":"Article 139115"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142651285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139032
Rong Jiang, Jiading Wang, Tao Xiao, Dengfei Zhang
Loess, an aeolian and unsaturated deposit, is highly sensitive to water. It can swiftly cause a series of detrimental effects including soil erosion, water and soil losses, and slope instability under the action of water and loading. Consequently, enhancing the water stability of loess is paramount for mitigating these issues. This study systematically investigates the effect of sisal fibers on the disintegration characteristics and microstructure of Q3 Malan loess using a self-designed disintegration apparatus and scanning electron microscope (SEM). In addition, the disintegration ratio, rate, and microstructure between untreated loess and loess amended with sisal fibers are compared and analyzed. A quantitative analysis was conducted to assess how the sisal fiber dosage and curing period influence the disintegration characteristics of sisal fiber-amended loess. The results show that sisal fibers effectively enhance the resistance of soil to disintegration, with this resistance intensifying with increasing sisal fiber dosage and extended curing periods. Notably, when the curing period reached 3 days and the fiber dosage reached 0.45 %, the sisal fiber-amended loess did not disintegrate. The incorporation of sisal fibers results in a decrease in soil pore area, with a greater fiber dosage leading to a lower pore area. In addition, sisal fiber can promote the formation and accumulation of organic matter in the soil, which can not only improve the bonding energy between soil particles but also facilitate carbon sequestration. This study underscores the potential of sisal fiber as a green and environmentally friendly modifier for loess, offering a promising solution for mitigating soil erosion and slope instability by enhancing the resistance of the soil to water-induced disintegration.
{"title":"Effect of sisal fibers on the disintegration characteristics of sisal fiber-amended loess","authors":"Rong Jiang, Jiading Wang, Tao Xiao, Dengfei Zhang","doi":"10.1016/j.conbuildmat.2024.139032","DOIUrl":"10.1016/j.conbuildmat.2024.139032","url":null,"abstract":"<div><div>Loess, an aeolian and unsaturated deposit, is highly sensitive to water. It can swiftly cause a series of detrimental effects including soil erosion, water and soil losses, and slope instability under the action of water and loading. Consequently, enhancing the water stability of loess is paramount for mitigating these issues. This study systematically investigates the effect of sisal fibers on the disintegration characteristics and microstructure of Q<sub>3</sub> Malan loess using a self-designed disintegration apparatus and scanning electron microscope (SEM). In addition, the disintegration ratio, rate, and microstructure between untreated loess and loess amended with sisal fibers are compared and analyzed. A quantitative analysis was conducted to assess how the sisal fiber dosage and curing period influence the disintegration characteristics of sisal fiber-amended loess. The results show that sisal fibers effectively enhance the resistance of soil to disintegration, with this resistance intensifying with increasing sisal fiber dosage and extended curing periods. Notably, when the curing period reached 3 days and the fiber dosage reached 0.45 %, the sisal fiber-amended loess did not disintegrate. The incorporation of sisal fibers results in a decrease in soil pore area, with a greater fiber dosage leading to a lower pore area. In addition, sisal fiber can promote the formation and accumulation of organic matter in the soil, which can not only improve the bonding energy between soil particles but also facilitate carbon sequestration. This study underscores the potential of sisal fiber as a green and environmentally friendly modifier for loess, offering a promising solution for mitigating soil erosion and slope instability by enhancing the resistance of the soil to water-induced disintegration.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139032"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139062
Zhe Huang , Jiazhang Cao , Fuyuan Gong , Ding Nie , Wenwei Li , Peng Lin , He Zhang
Hydraulic concrete structures in cold regions are vulnerable to freeze-thaw damage. This paper proposes a multi-scale simulation analysis approach to investigate the mechanical properties and frost resistance of Low-heat Portland (LHP) cement, Moderate-heat Portland (MHP) cement, and Ordinary Portland cement (OPC) concrete. The hydration heat, hydration degree, pore size distribution, and compressive strength of LHP, MHP, and OPC concrete at different curing ages, as well as the ice amount, expansion strain, and mechanical properties under different freeze-thaw cycles are calculated and compared. Due to the lower early-hydrated C3S content of LHP and the higher later-hydrated C2S content, the porosity of LHP after 90d curing is lower than that of MHP and OPC, resulting in better mechanical properties and frost resistance. On this basis, the evolution model proposed in this paper can quantitative analysis the frost resistance of cement paste based on different content of C3S and C2S, which provided a feasible method for predicting the frost resistance of hydraulic concrete structures in cold regions.
{"title":"Multi-scale thermo-poro-mechanical simulation of the frost resistance of low-heat and moderate-heat hydraulic concrete considering the aging microstructure","authors":"Zhe Huang , Jiazhang Cao , Fuyuan Gong , Ding Nie , Wenwei Li , Peng Lin , He Zhang","doi":"10.1016/j.conbuildmat.2024.139062","DOIUrl":"10.1016/j.conbuildmat.2024.139062","url":null,"abstract":"<div><div>Hydraulic concrete structures in cold regions are vulnerable to freeze-thaw damage. This paper proposes a multi-scale simulation analysis approach to investigate the mechanical properties and frost resistance of Low-heat Portland (LHP) cement, Moderate-heat Portland (MHP) cement, and Ordinary Portland cement (OPC) concrete. The hydration heat, hydration degree, pore size distribution, and compressive strength of LHP, MHP, and OPC concrete at different curing ages, as well as the ice amount, expansion strain, and mechanical properties under different freeze-thaw cycles are calculated and compared. Due to the lower early-hydrated C<sub>3</sub>S content of LHP and the higher later-hydrated C<sub>2</sub>S content, the porosity of LHP after 90d curing is lower than that of MHP and OPC, resulting in better mechanical properties and frost resistance. On this basis, the evolution model proposed in this paper can quantitative analysis the frost resistance of cement paste based on different content of C<sub>3</sub>S and C<sub>2</sub>S, which provided a feasible method for predicting the frost resistance of hydraulic concrete structures in cold regions.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139062"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659223","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.conbuildmat.2024.139066
Zhuo Liu , Weina Meng
To address this challenge of shortage of specification-grade fly ash(SGFA) and recycling of off-specification fly ash(OSFA), this research proposes a novel approach of coating OSFA with nano-CaCO3. This improves the surface characteristics of the particles and creates nucleation sites that enhance cement hydration, thus potentially improving the fundamental properties of cementitious materials incorporating OSFA. The first step in this process involves optimizing the quantity of nano-CaCO3 coating on OSFA to achieve the best mechanical properties for concrete applications. Subsequently, experimental investigations were conducted to compare the mechanical properties of cementitious pastes prepared with original OSFA, OSFA and nano-CaCO3 powders, and coated OSFA. Isothermal calorimetry and pore structure analyses indicated that the coating treatment transformed OSFA from a detrimental additive to a beneficial one for concrete. This coating significantly strengthened the OSFA particles and promoted cement hydration, consequently enhancing the mechanical properties of cementitious composites containing OSFA. This innovative method offers a promising solution for addressing the fly ash shortage in the concrete industry while minimizing the need for land disposal of OSFA.
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Ammonium polyphosphate (APP) has been commonly used as a commercial flame retardant. However, its application to flame-retardant epoxy resins (EP) has been faced with the problems of high smoke generation and degradation of mechanical properties. This has greatly limited its wide application in the field of building materials. In this work, a highly efficient flame retardant APP@M-LDH was prepared by using ZIF-67 as a bridge, and its microstructure, chemical composition, and thermal stability were comprehensively characterized. Due to the synergistic flame retardant effect of APP and LDH and the catalytic oxidation of copper and cobalt ions in the LDH structure in the gas phase, the peak heat release rate (PHRR), total heat release rate (THR) and total smoke release rate (TSP) of EP/4APP@M-LDH were reduced by 34 %, 35.3 % and 40.3 %, respectively, which achieved the high efficiency of flame retardancy for EP. In addition, due to the three-dimensional structure of the synthesized CuCo-LDH, which can expose more hydrogen bonds, the flexural strength and flexural modulus of EP/4APP@M-LDH were significantly increased by 54.1 % and 63.6 %, respectively. This study provides new ideas for the design of efficient flame retardants for EP.
{"title":"ZIF-67-derived CuCo-layered double hydroxide/ammonium polyphosphate hybrid for highly efficient flame retardant epoxy resin via synergistic catalytic carbonization","authors":"Yiwei Geng , Junxiu Piao , Xinliang Liu , Xilei Chen , Chuanmei Jiao","doi":"10.1016/j.conbuildmat.2024.139102","DOIUrl":"10.1016/j.conbuildmat.2024.139102","url":null,"abstract":"<div><div>Ammonium polyphosphate (APP) has been commonly used as a commercial flame retardant. However, its application to flame-retardant epoxy resins (EP) has been faced with the problems of high smoke generation and degradation of mechanical properties. This has greatly limited its wide application in the field of building materials. In this work, a highly efficient flame retardant APP@M-LDH was prepared by using ZIF-67 as a bridge, and its microstructure, chemical composition, and thermal stability were comprehensively characterized. Due to the synergistic flame retardant effect of APP and LDH and the catalytic oxidation of copper and cobalt ions in the LDH structure in the gas phase, the peak heat release rate (PHRR), total heat release rate (THR) and total smoke release rate (TSP) of EP/4APP@M-LDH were reduced by 34 %, 35.3 % and 40.3 %, respectively, which achieved the high efficiency of flame retardancy for EP. In addition, due to the three-dimensional structure of the synthesized CuCo-LDH, which can expose more hydrogen bonds, the flexural strength and flexural modulus of EP/4APP@M-LDH were significantly increased by 54.1 % and 63.6 %, respectively. This study provides new ideas for the design of efficient flame retardants for EP.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"453 ","pages":"Article 139102"},"PeriodicalIF":7.4,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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