Pub Date : 2025-02-17DOI: 10.1016/j.conbuildmat.2025.140371
Zundong Liang , Chao Xing , Yiqiu Tan , Bo Liu , Wei Wang
In aggregate skeleton structure research, the distribution of aggregate contact points is a key factor affecting structural stability under loading. However, traditional image segmentation methods struggle to accurately segment aggregates in CT images, making the study of aggregate contact in three-dimensional space in real specimens a challenge. To address this, this study first proposes an adaptive bilateral filtering algorithm for CT image preprocessing to enhance edge details. Then, an improved U-Net algorithm is proposed, which combines Inception convolution modules, residual connections, spatial attention mechanisms, and a novel loss function incorporating boundary information, effectively solving the adhesion issue in aggregate segmentation. Finally, based on the centroids and spatial orientation of aggregates, an approximate ellipsoid model is constructed, and the contact number of the main skeleton aggregates is calculated, further analyzing the evolution of contact numbers during loading.
{"title":"Investigation of three-dimensional aggregate contact evolution using an enhanced image segmentation algorithm","authors":"Zundong Liang , Chao Xing , Yiqiu Tan , Bo Liu , Wei Wang","doi":"10.1016/j.conbuildmat.2025.140371","DOIUrl":"10.1016/j.conbuildmat.2025.140371","url":null,"abstract":"<div><div>In aggregate skeleton structure research, the distribution of aggregate contact points is a key factor affecting structural stability under loading. However, traditional image segmentation methods struggle to accurately segment aggregates in CT images, making the study of aggregate contact in three-dimensional space in real specimens a challenge. To address this, this study first proposes an adaptive bilateral filtering algorithm for CT image preprocessing to enhance edge details. Then, an improved U-Net algorithm is proposed, which combines Inception convolution modules, residual connections, spatial attention mechanisms, and a novel loss function incorporating boundary information, effectively solving the adhesion issue in aggregate segmentation. Finally, based on the centroids and spatial orientation of aggregates, an approximate ellipsoid model is constructed, and the contact number of the main skeleton aggregates is calculated, further analyzing the evolution of contact numbers during loading.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140371"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428144","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 : 2025-02-17DOI: 10.1016/j.conbuildmat.2025.140447
Zhikun Zhang , Yuanqing Gao , Yufei Xu , Mengying Yun , Boxiong Shen , Jiao Ma , Lina Liu
In recent years, the conversion of municipal solid waste incineration bottom ash (MSWIBA) into geopolymer has attracted much attention. However, the properties of MSWIBA based geopolymers were limited by the absence of reactivity and active calcium. In this work, a novel method of preparing MSWIBA based geopolymers by adding CaO extracted from MSWIBA was proposed. The effects of thermally treated MSWIBA (TBA700) (10–90 wt%) and self-extracted CaO (B-CaO) (0–10 wt%) on the compressive strength, micro-morphology, pore structure, and heavy metal leaching of geopolymers were investigated. The phase transformation, property, molecular structure, micro-morphology, pore structure and heavy metal content of the geopolymers were characterized and tested using X-ray Diffraction (XRD), Thermo-gravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Mercury Infiltration Porosity (MIP) and Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The results showed that the geopolymers prepared with the addition of B-CaO showed better properties due to the generation of more hydrate calcium silicate (C-S-H). The compressive strength of the geopolymers increased with the addition of B-CaO and TBA700. When the TBA700 content was increased to 30 %, the compressive strength of the geopolymers reached 9.21 MPa at 28 d. Furthermore, the addition of 5 % B-CaO resulted in the highest compressive strength of 23.36 MPa under the same curing conditions. All the prepared geopolymers showed the leaching concentrations of Cd, Cr, Cu, Zn, and Pb that were substantially below the regulatory limits set by GB18598–2019. Therefore, MSWIBA based geopolymers by adding its self-extracted CaO showed a promising strategy to improve the product properties and provided the foundation for the recycling of calcium-containing solid wastes into geopolymer.
{"title":"Preparation and performance improvement of municipal solid waste incineration bottom ash based geopolymer modified by self-extracted CaO","authors":"Zhikun Zhang , Yuanqing Gao , Yufei Xu , Mengying Yun , Boxiong Shen , Jiao Ma , Lina Liu","doi":"10.1016/j.conbuildmat.2025.140447","DOIUrl":"10.1016/j.conbuildmat.2025.140447","url":null,"abstract":"<div><div>In recent years, the conversion of municipal solid waste incineration bottom ash (MSWIBA) into geopolymer has attracted much attention. However, the properties of MSWIBA based geopolymers were limited by the absence of reactivity and active calcium. In this work, a novel method of preparing MSWIBA based geopolymers by adding CaO extracted from MSWIBA was proposed. The effects of thermally treated MSWIBA (TBA700) (10–90 wt%) and self-extracted CaO (B-CaO) (0–10 wt%) on the compressive strength, micro-morphology, pore structure, and heavy metal leaching of geopolymers were investigated. The phase transformation, property, molecular structure, micro-morphology, pore structure and heavy metal content of the geopolymers were characterized and tested using X-ray Diffraction (XRD), Thermo-gravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Mercury Infiltration Porosity (MIP) and Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The results showed that the geopolymers prepared with the addition of B-CaO showed better properties due to the generation of more hydrate calcium silicate (C-S-H). The compressive strength of the geopolymers increased with the addition of B-CaO and TBA700. When the TBA700 content was increased to 30 %, the compressive strength of the geopolymers reached 9.21 MPa at 28 d. Furthermore, the addition of 5 % B-CaO resulted in the highest compressive strength of 23.36 MPa under the same curing conditions. All the prepared geopolymers showed the leaching concentrations of Cd, Cr, Cu, Zn, and Pb that were substantially below the regulatory limits set by GB18598–2019. Therefore, MSWIBA based geopolymers by adding its self-extracted CaO showed a promising strategy to improve the product properties and provided the foundation for the recycling of calcium-containing solid wastes into geopolymer.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140447"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143428093","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 : 2025-02-17DOI: 10.1016/j.conbuildmat.2025.140403
Fangyu Han , Jialiang Wang , Xuping Ji , Shuohui Chen , Jianzhong Liu , Min Wu , Jiaping Liu
Strength insufficiency in ultra-high performance cementitious composites (UHPCC) during winter construction has attracted attention, yet the mechanisms underlying the impacts of mid-to-low temperatures on strength development remain unclear. This study systematically investigated the mechanisms underlying the early-age strength insufficiency of UHPCC within the temperature range of 5°C to 20°C. The effects of curing temperatures on hydration reactions, microstructural evolution, and mechanical strength were comprehensively analyzed. The results revealed that during the early hydration stage (0–3d), lower curing temperatures (5°C, 10°C) significantly reduced hydration reaction rates and the formation of hydration products, leading to lower matrix density and early strength compared to 20°C, demonstrating a pronounced thermodynamic response. With prolonged curing time (7–28d), lower temperatures, particularly at 5°C, facilitated the accumulation of hydration products and pore structure refinement, partially mitigating adverse effects of initial delays. Microscopic characterizations (SEM-EDS, TGA, FTIR, XRD) confirmed that low temperatures influenced the formation and transformation of critical hydration products such as C-(A)-S-H gel and Ca(OH)2, while potentially inducing nano- and microscale structural defects in the material matrix. Hydration kinetics analysis indicated that UHPCC hydration rates were highly sensitive to temperature, with a reduction to 5°C lowering reaction rates by approximately 58.9 %. These complex hydration behavior of UHPCC contribute to the nonlinear decline in the strength development as temperatures decrease, with strength losses reaching as high as 31.8 % at 10°C. The findings provide scientific insights and practical guidance for optimizing UHPCC performance in real-world low-temperature construction environments.
{"title":"Insights into the hydration kinetics and microstructural evolution of ultra-high performance cementitious composite at mid-to-low curing temperatures","authors":"Fangyu Han , Jialiang Wang , Xuping Ji , Shuohui Chen , Jianzhong Liu , Min Wu , Jiaping Liu","doi":"10.1016/j.conbuildmat.2025.140403","DOIUrl":"10.1016/j.conbuildmat.2025.140403","url":null,"abstract":"<div><div>Strength insufficiency in ultra-high performance cementitious composites (UHPCC) during winter construction has attracted attention, yet the mechanisms underlying the impacts of mid-to-low temperatures on strength development remain unclear. This study systematically investigated the mechanisms underlying the early-age strength insufficiency of UHPCC within the temperature range of 5°C to 20°C. The effects of curing temperatures on hydration reactions, microstructural evolution, and mechanical strength were comprehensively analyzed. The results revealed that during the early hydration stage (0–3d), lower curing temperatures (5°C, 10°C) significantly reduced hydration reaction rates and the formation of hydration products, leading to lower matrix density and early strength compared to 20°C, demonstrating a pronounced thermodynamic response. With prolonged curing time (7–28d), lower temperatures, particularly at 5°C, facilitated the accumulation of hydration products and pore structure refinement, partially mitigating adverse effects of initial delays. Microscopic characterizations (SEM-EDS, TGA, FTIR, XRD) confirmed that low temperatures influenced the formation and transformation of critical hydration products such as C-(A)-S-H gel and Ca(OH)<sub>2</sub>, while potentially inducing nano- and microscale structural defects in the material matrix. Hydration kinetics analysis indicated that UHPCC hydration rates were highly sensitive to temperature, with a reduction to 5°C lowering reaction rates by approximately 58.9 %. These complex hydration behavior of UHPCC contribute to the nonlinear decline in the strength development as temperatures decrease, with strength losses reaching as high as 31.8 % at 10°C. The findings provide scientific insights and practical guidance for optimizing UHPCC performance in real-world low-temperature construction environments.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140403"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419394","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 : 2025-02-17DOI: 10.1016/j.conbuildmat.2025.140451
Yang Liu , Bingyang He , Zhaohou Chen , Xiaohuan Jing , Daqiang Cang , Yongchao Zheng , Lingling Zhang
Not only capture CO2, the carbonated steel slag (CSS) can be used as supplementary cementitious materials to exhibit excellent physical and chemical properties. In order to understand the mineral phase evolution and hydration mechanism of CSS in alkali-activated materials (AAMs), the contribution of calcite and calcium-containing minerals (Ca-minerals) to the hydration degree was deeply investigated, and the microstructure and mechanical properties of AAMs were explored. The results showed that AAMs prepared by CSS exhibited stronger early mechanical properties and lower drying shrinkage than AAMs prepared by steel slag (SS). The compressive strength of AAMs prepared by 30 % CSS and 70 % fly ash was 54.2 % greater than that of AAMs prepared with SS in the same conditions. The EDS test suggested that the carbonation product calcite possessed a higher specific surface area and provided more nucleation sites. Both calcite and Ca-minerals could provide Ca2 + into the silica-aluminate network. The decomposition reaction rate of calcite stabilized at around 30 % when FA was incorporated in paste, and the remaining calcite could fill the pores to improve the strength. Interestingly, 87.6 % of calcite mainly produced pirssonite when only CSS existed in paste. Besides, the Ca-minerals (srebrodolskite, brownmillerite, and all mayenite) in CSS possessed higher reactivity compared with SS, and underwent rapid decomposition under alkali activation conditions. Carbon footprint analysis showed that AAMs prepared with CSS resulted in the lowest carbon emission of 308.4 kg CO2-eq, providing a novel approach for the application of CSS.
{"title":"Contribution of calcium-containing minerals on the mechanical properties of alkali-activated materials: A study of carbonation steel slag","authors":"Yang Liu , Bingyang He , Zhaohou Chen , Xiaohuan Jing , Daqiang Cang , Yongchao Zheng , Lingling Zhang","doi":"10.1016/j.conbuildmat.2025.140451","DOIUrl":"10.1016/j.conbuildmat.2025.140451","url":null,"abstract":"<div><div>Not only capture CO<sub>2</sub>, the carbonated steel slag (CSS) can be used as supplementary cementitious materials to exhibit excellent physical and chemical properties. In order to understand the mineral phase evolution and hydration mechanism of CSS in alkali-activated materials (AAMs), the contribution of calcite and calcium-containing minerals (Ca-minerals) to the hydration degree was deeply investigated, and the microstructure and mechanical properties of AAMs were explored. The results showed that AAMs prepared by CSS exhibited stronger early mechanical properties and lower drying shrinkage than AAMs prepared by steel slag (SS). The compressive strength of AAMs prepared by 30 % CSS and 70 % fly ash was 54.2 % greater than that of AAMs prepared with SS in the same conditions. The EDS test suggested that the carbonation product calcite possessed a higher specific surface area and provided more nucleation sites. Both calcite and Ca-minerals could provide Ca<sup>2 +</sup> into the silica-aluminate network. The decomposition reaction rate of calcite stabilized at around 30 % when FA was incorporated in paste, and the remaining calcite could fill the pores to improve the strength. Interestingly, 87.6 % of calcite mainly produced pirssonite when only CSS existed in paste. Besides, the Ca-minerals (srebrodolskite, brownmillerite, and all mayenite) in CSS possessed higher reactivity compared with SS, and underwent rapid decomposition under alkali activation conditions. Carbon footprint analysis showed that AAMs prepared with CSS resulted in the lowest carbon emission of 308.4 kg CO<sub>2</sub>-eq, providing a novel approach for the application of CSS.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140451"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427580","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 : 2025-02-17DOI: 10.1016/j.conbuildmat.2025.140388
Haihui Duan , Henglong Zhang , Songtao Lv , Weiwei Lu , Dongdong Ge , Ruiyao Jiang , Jinping Wang
Zinc oxide/expanded vermiculite composite (ZnO/EVMT), a novel modifier, can synergistically improve the thermal oxidative and ultraviolet (UV) aging resistance of bituminous mixture. However, the existing characteristics of ZnO/EVMT and the recovered binder in mixture is unclear, preventing the understanding of its aging behavior retarding mechanism. In this research, the modified bituminous mixture was prepared and treated with four aging methods, including short-term and long-term oven aging, long-term continuous and holoclimate UV aging. The ZnO/EVMT and bituminous binder in the aged mixtures were recovered. Then, the microscopic and thermodynamic characteristics of the recovered ZnO/EVMT and the retarded aging behavior of the recovered binder were characterized. Finally, the aging behavior retarding mechanism of ZnO/EVMT modified bituminous mixture was revealed. Results show that the recovered ZnO/EVMT can maintain the integrity of its original structure in both bituminous binder and mixture, and is distributed on the bitumen film surface of the loose mixture. ZnO/EVMT modified bitumen forms an exfoliation phase structure, enhancing bitumen heat barrier effect. The incorporation of ZnO/EVMT into bituminous mixture can reduce the production of carbonyl or sulfoxide group contents and the increment of large-size molecule content under different aging methods. The aging behavior retarding mechanism lies in the two-dimensional layered structure of its EVMT component and the semiconductor characteristics of its ZnO particle component, as well as the synergistic effect between the two components. Therefore, it can be expected that the mechanism by which ZnO/EVMT retards mixture aging behavior is beneficial not only for regulating its own performance and promoting its application but also for extending the expected service life and enhancing the durability of bituminous pavements.
{"title":"Revealing aging behavior retarding mechanism of zinc oxide/expanded vermiculite composite modified bituminous mixture","authors":"Haihui Duan , Henglong Zhang , Songtao Lv , Weiwei Lu , Dongdong Ge , Ruiyao Jiang , Jinping Wang","doi":"10.1016/j.conbuildmat.2025.140388","DOIUrl":"10.1016/j.conbuildmat.2025.140388","url":null,"abstract":"<div><div>Zinc oxide/expanded vermiculite composite (ZnO/EVMT), a novel modifier, can synergistically improve the thermal oxidative and ultraviolet (UV) aging resistance of bituminous mixture. However, the existing characteristics of ZnO/EVMT and the recovered binder in mixture is unclear, preventing the understanding of its aging behavior retarding mechanism. In this research, the modified bituminous mixture was prepared and treated with four aging methods, including short-term and long-term oven aging, long-term continuous and holoclimate UV aging. The ZnO/EVMT and bituminous binder in the aged mixtures were recovered. Then, the microscopic and thermodynamic characteristics of the recovered ZnO/EVMT and the retarded aging behavior of the recovered binder were characterized. Finally, the aging behavior retarding mechanism of ZnO/EVMT modified bituminous mixture was revealed. Results show that the recovered ZnO/EVMT can maintain the integrity of its original structure in both bituminous binder and mixture, and is distributed on the bitumen film surface of the loose mixture. ZnO/EVMT modified bitumen forms an exfoliation phase structure, enhancing bitumen heat barrier effect. The incorporation of ZnO/EVMT into bituminous mixture can reduce the production of carbonyl or sulfoxide group contents and the increment of large-size molecule content under different aging methods. The aging behavior retarding mechanism lies in the two-dimensional layered structure of its EVMT component and the semiconductor characteristics of its ZnO particle component, as well as the synergistic effect between the two components. Therefore, it can be expected that the mechanism by which ZnO/EVMT retards mixture aging behavior is beneficial not only for regulating its own performance and promoting its application but also for extending the expected service life and enhancing the durability of bituminous pavements.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140388"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419395","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 : 2025-02-17DOI: 10.1016/j.conbuildmat.2025.140361
Dedong Guo , Shihua Yang , Meng Xu , Xiang Li , Xupeng Sun , Teng Wang , Yutong An , Sha Huang
To efficiently REOB and address the technical challenge of improving the low-temperature performance of PPAMB, this study investigates the preparation and performance of composite modified bitumen using REOB and PPA as additives. The micro-mechanisms and macroscopic properties of the composite modified bitumen were systematically studied. First, the optimal contents of REOB and PPA were determined based on fundamental performance indicators. Second, the modification mechanisms of REOB and PPA on bitumen were revealed through micro-analysis techniques, including XRF, SARA fractionation, infrared spectroscopy, and FM. Third, the effects of PPA and REOB on the macroscopic performance of bitumen were evaluated using DSR, BBR tests, and adhesion tests. Finally, the macro-level road performance of PPA-REOB MB mixtures was compared with PPAMB mixtures to validate the findings. The results indicate that the optimal contents of PPA and REOB are 0.5 % and 1.8 %, respectively, yielding the best fundamental indicators for PPA-REOB MB. REOB can disperse and solubilize heavy fractions in bitumen, primarily promoting the transition of the bitumen system to a sol structure through physical interactions. This significantly enhances the low-temperature performance of PPAMB, reducing its stiffness modulus (S) at −6°C by 26.4 % and increasing its creep rate (m-value) by 12 %. However, REOB also slightly decreases the high-temperature performance of PPAMB, with a 19.97 % reduction in rutting factor at 76°C and a 1.55 % increase in phase angle, although the performance remains notably superior to that of matrix bitumen. Furthermore, the adhesion rate of PPA-REOB MB improves by 14.13 % compared to matrix bitumen but decreases by 5.5 % compared to PPAMB. PPA-REOB MB mixtures exhibit significantly better low-temperature performance than PPAMB mixtures, although with a slight reduction in high-temperature performance.
{"title":"Preparation and performance study of PPA-REOB composite modified bitumen","authors":"Dedong Guo , Shihua Yang , Meng Xu , Xiang Li , Xupeng Sun , Teng Wang , Yutong An , Sha Huang","doi":"10.1016/j.conbuildmat.2025.140361","DOIUrl":"10.1016/j.conbuildmat.2025.140361","url":null,"abstract":"<div><div>To efficiently REOB and address the technical challenge of improving the low-temperature performance of PPAMB, this study investigates the preparation and performance of composite modified bitumen using REOB and PPA as additives. The micro-mechanisms and macroscopic properties of the composite modified bitumen were systematically studied. First, the optimal contents of REOB and PPA were determined based on fundamental performance indicators. Second, the modification mechanisms of REOB and PPA on bitumen were revealed through micro-analysis techniques, including XRF, SARA fractionation, infrared spectroscopy, and FM. Third, the effects of PPA and REOB on the macroscopic performance of bitumen were evaluated using DSR, BBR tests, and adhesion tests. Finally, the macro-level road performance of PPA-REOB MB mixtures was compared with PPAMB mixtures to validate the findings. The results indicate that the optimal contents of PPA and REOB are 0.5 % and 1.8 %, respectively, yielding the best fundamental indicators for PPA-REOB MB. REOB can disperse and solubilize heavy fractions in bitumen, primarily promoting the transition of the bitumen system to a sol structure through physical interactions. This significantly enhances the low-temperature performance of PPAMB, reducing its stiffness modulus (S) at −6°C by 26.4 % and increasing its creep rate (m-value) by 12 %. However, REOB also slightly decreases the high-temperature performance of PPAMB, with a 19.97 % reduction in rutting factor at 76°C and a 1.55 % increase in phase angle, although the performance remains notably superior to that of matrix bitumen. Furthermore, the adhesion rate of PPA-REOB MB improves by 14.13 % compared to matrix bitumen but decreases by 5.5 % compared to PPAMB. PPA-REOB MB mixtures exhibit significantly better low-temperature performance than PPAMB mixtures, although with a slight reduction in high-temperature performance.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140361"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427982","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 : 2025-02-17DOI: 10.1016/j.conbuildmat.2025.140436
Qiuchao Li , Yingfang Fan , Yulong Zhao , Hao Chen , Surendra P. Shah
The partial replacement of cement with fly ash (FA) has the potential to reduce industrial waste and carbon emissions. FA-cement systems exhibit lower strength during the early hydration period, which limits their applications. Nano-metakaolin (NMK) is known to enhance early strength, yet its effect on the hydration and microstructure development of FA cement systems remains unclear. This study utilizes the alternating current impedance spectroscopy (ACIS) method to investigate the hydration properties and microstructural evolution of NMK/FA cement mortar. The suitability of the ACIS method was validated through the use of TGA, XRD, and MIP tests. A suitable equivalent circuit model Rs(CPE1(Rct1W1))(CPE2(Rct2W2)) was determined to analyze the ACIS data. Furthermore, the relationships between strength and ACIS parameters of NMK/FA cement mortar were established. The results indicate that NMK promotes the formation of hydration products and refines the pores of FA cement paste, particularly during the 7–14 d. The ACIS observations are consistent with the conclusions derived from XRD and TGA. FA decreases the bulk resistance of cement mortar, whereas NMK significantly increases it, especially during the 7–14 d period. A synergistic pozzolanic reaction between NMK and FA occurs within the 7–14 d period, which is crucial for the long-term performance and durability of NMK/FA cement systems. When 5 % NMK is added to the cement paste with 30 % FA, the pores larger than 1 μm significantly decrease. Compared to FA30N0, the compressive strength of FA30N5 cement mortar increased by 12.9 %, 35.4 %, 20.0 %, and 8.3 % at 3, 7, 14, and 28 d, respectively. Furthermore, a logarithmic relationship exists between compressive and flexural strengths, the diffusion impedance coefficient and the bulk resistance of the NMK/FA cement mortar.
{"title":"AC impedance spectroscopy interpretation of the hydration behavior for cement mortar containing fly ash and nano-metakaolin","authors":"Qiuchao Li , Yingfang Fan , Yulong Zhao , Hao Chen , Surendra P. Shah","doi":"10.1016/j.conbuildmat.2025.140436","DOIUrl":"10.1016/j.conbuildmat.2025.140436","url":null,"abstract":"<div><div>The partial replacement of cement with fly ash (FA) has the potential to reduce industrial waste and carbon emissions. FA-cement systems exhibit lower strength during the early hydration period, which limits their applications. Nano-metakaolin (NMK) is known to enhance early strength, yet its effect on the hydration and microstructure development of FA cement systems remains unclear. This study utilizes the alternating current impedance spectroscopy (ACIS) method to investigate the hydration properties and microstructural evolution of NMK/FA cement mortar. The suitability of the ACIS method was validated through the use of TGA, XRD, and MIP tests. A suitable equivalent circuit model <em>R</em><sub>s</sub>(CPE<sub>1</sub>(<em>R</em><sub>ct1</sub><em>W</em><sub>1</sub>))(CPE<sub>2</sub>(<em>R</em><sub>ct2</sub><em>W</em><sub>2</sub>)) was determined to analyze the ACIS data. Furthermore, the relationships between strength and ACIS parameters of NMK/FA cement mortar were established. The results indicate that NMK promotes the formation of hydration products and refines the pores of FA cement paste, particularly during the 7–14 d. The ACIS observations are consistent with the conclusions derived from XRD and TGA. FA decreases the bulk resistance of cement mortar, whereas NMK significantly increases it, especially during the 7–14 d period. A synergistic pozzolanic reaction between NMK and FA occurs within the 7–14 d period, which is crucial for the long-term performance and durability of NMK/FA cement systems. When 5 % NMK is added to the cement paste with 30 % FA, the pores larger than 1 μm significantly decrease. Compared to FA30N0, the compressive strength of FA30N5 cement mortar increased by 12.9 %, 35.4 %, 20.0 %, and 8.3 % at 3, 7, 14, and 28 d, respectively. Furthermore, a logarithmic relationship exists between compressive and flexural strengths, the diffusion impedance coefficient and the bulk resistance of the NMK/FA cement mortar.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140436"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143419396","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 : 2025-02-17DOI: 10.1016/j.conbuildmat.2025.140363
Alessio Gabrielli, Greta Ugolotti, Giulia Masi, Enrico Sassoni
The use of aqueous solutions of diammonium hydrogen phosphate (DAP) to form hydroxyapatite (HAP) in situ, on the surface and inside the pores and cracks in heritage building materials (e.g. stones, mortars, frescoes, stuccoes), is receiving increasing attention, because of the advantages that this method offers compared to alternative treatments. However, heritage substrates are often affected by the presence of soluble salts when conservation treatments are applied, which can interfere with the expected chemical reactions. Therefore, the present study aimed at assessing the effects of three types of salt (NaCl, NaNO3 and Na2SO4) present in a reference type of substrate (marble) when treated with DAP solutions. Marble samples were preliminarily contaminated with increasing amounts of the three salts, to reach levels of contamination that can be regarded as low, medium and high according to existing standards. Then, the salt-contaminated samples were consolidated by treatment with a solution containing 1 M DAP+ 1 mM CaCl2, applied by poultice. The possible interference of foreign ions deriving from salt dissolution on in situ HAP formation was investigated by XRD and SEM-EDS, aimed at assessing whether ionic substitutions in the HAP crystal occurred and/or foreign ions were adsorbed onto the new phases. The results of the study indicate that, independently of the initial salt content, HAP and/or carbonate HAP (containing CO32- ions from the substrate and from the atmosphere) were formed. These new phases proved to be resistant to accelerated ageing, consisting in immersion in water for 24 h. Therefore, the presence of NaCl, NaNO3 and Na2SO4 (even in high amounts, corresponding to high risk) was found not to negatively affect the outcome of the DAP treatment in the conditions investigated in this study.
{"title":"Marble consolidation by ammonium phosphate (DAP): Do soluble salts in the substrate interfere with in situ apatite formation?","authors":"Alessio Gabrielli, Greta Ugolotti, Giulia Masi, Enrico Sassoni","doi":"10.1016/j.conbuildmat.2025.140363","DOIUrl":"10.1016/j.conbuildmat.2025.140363","url":null,"abstract":"<div><div>The use of aqueous solutions of diammonium hydrogen phosphate (DAP) to form hydroxyapatite (HAP) <em>in situ</em>, on the surface and inside the pores and cracks in heritage building materials (e.g. stones, mortars, frescoes, stuccoes), is receiving increasing attention, because of the advantages that this method offers compared to alternative treatments. However, heritage substrates are often affected by the presence of soluble salts when conservation treatments are applied, which can interfere with the expected chemical reactions. Therefore, the present study aimed at assessing the effects of three types of salt (NaCl, NaNO<sub>3</sub> and Na<sub>2</sub>SO<sub>4</sub>) present in a reference type of substrate (marble) when treated with DAP solutions. Marble samples were preliminarily contaminated with increasing amounts of the three salts, to reach levels of contamination that can be regarded as low, medium and high according to existing standards. Then, the salt-contaminated samples were consolidated by treatment with a solution containing 1 M DAP+ 1 mM CaCl<sub>2</sub>, applied by poultice. The possible interference of foreign ions deriving from salt dissolution on <em>in situ</em> HAP formation was investigated by XRD and SEM-EDS, aimed at assessing whether ionic substitutions in the HAP crystal occurred and/or foreign ions were adsorbed onto the new phases. The results of the study indicate that, independently of the initial salt content, HAP and/or carbonate HAP (containing CO<sub>3</sub><sup>2-</sup> ions from the substrate and from the atmosphere) were formed. These new phases proved to be resistant to accelerated ageing, consisting in immersion in water for 24 h. Therefore, the presence of NaCl, NaNO<sub>3</sub> and Na<sub>2</sub>SO<sub>4</sub> (even in high amounts, corresponding to high risk) was found not to negatively affect the outcome of the DAP treatment in the conditions investigated in this study.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140363"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427579","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 : 2025-02-17DOI: 10.1016/j.conbuildmat.2025.140439
Peng Lin , Yinjie Wang , Chuang Yu , Hao Wang , Kunpeng Song , Xue Bi , Jin Cao , Keshan Zhang , Ye-Tang Pan , Jiping Liu
Zeolite imidazole salt frame (ZIF-67) has a highly regular microporous structure, large specific surface and certain flame retardant properties, and 2-methylimidazole in it is very sensitive to protolation reaction, so ZIF-67 can be etched to get more properties. However, different etching methods often yield different results. So we use H+ produced by the synthesis of 2-aminopyrazine and hexachlorophosphazene (HCCP) to directly or synchronously etch ZIF-67. Two kinds of flame retardants with sugar-frosting structure and fig-like structure with UV shielding capability are designed and synthesized, and the two etching methods are compared. When 2.0 wt% flame retardant is added to epoxy resin system, the total heat release rate of EP/AHCTP epoxy composite is reduced by 29.4 %, the peak heat release rate of EP/CHCTP composite is reduced by 38.5 %, and the CO and CO2 production of EP/CHCTP composite are reduced by 45.2 % and 40.1 %, respectively. The UV shielding performance is improved while the mechanical properties are maintained. In the background of the rapid development of MOFs modification research, we compare two methods of binding ZIF-67 with small molecule phosphazenes and suggest its potential application in flame retardancy and UV resistance of EP.
{"title":"Tuning the polycondensation of phosphazenes with ZIF-67 and its effects on UV/fire resistant epoxy composites","authors":"Peng Lin , Yinjie Wang , Chuang Yu , Hao Wang , Kunpeng Song , Xue Bi , Jin Cao , Keshan Zhang , Ye-Tang Pan , Jiping Liu","doi":"10.1016/j.conbuildmat.2025.140439","DOIUrl":"10.1016/j.conbuildmat.2025.140439","url":null,"abstract":"<div><div>Zeolite imidazole salt frame (ZIF-67) has a highly regular microporous structure, large specific surface and certain flame retardant properties, and 2-methylimidazole in it is very sensitive to protolation reaction, so ZIF-67 can be etched to get more properties. However, different etching methods often yield different results. So we use H<sup>+</sup> produced by the synthesis of 2-aminopyrazine and hexachlorophosphazene (HCCP) to directly or synchronously etch ZIF-67. Two kinds of flame retardants with sugar-frosting structure and fig-like structure with UV shielding capability are designed and synthesized, and the two etching methods are compared. When 2.0 wt% flame retardant is added to epoxy resin system, the total heat release rate of EP/AHCTP epoxy composite is reduced by 29.4 %, the peak heat release rate of EP/CHCTP composite is reduced by 38.5 %, and the CO and CO<sub>2</sub> production of EP/CHCTP composite are reduced by 45.2 % and 40.1 %, respectively. The UV shielding performance is improved while the mechanical properties are maintained. In the background of the rapid development of MOFs modification research, we compare two methods of binding ZIF-67 with small molecule phosphazenes and suggest its potential application in flame retardancy and UV resistance of EP.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"468 ","pages":"Article 140439"},"PeriodicalIF":7.4,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427983","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 : 2025-02-16DOI: 10.1016/j.conbuildmat.2025.140435
Chunyang Zhang , Tao Tan , Wenquan Duan , Wanru Li , Kaibin Hu , Jian Liao
In cold regions, flawed rocks are inevitably affected by freeze-thaw (FT) weathering and dynamic impact, and grouting or filling has become an effective means to improve their stability. In order to clarify the mechanical properties of flawed rocks with or without filling materials under dynamic loading, a series of FT cycle tests and impact tests were conducted on sandstone. The results indicate that the number of FT cycles significantly deteriorates the dynamic peak strength, apparent stiffness, and energy parameters, which are strongly correlated with the flaw inclination angle. In addition, the mechanical properties and energy absorption capacity of the filled specimens were significantly improved, but were affected by the number of FT cycles and flaw inclination angle. The strength and energy enhancement coefficients of all specimens are between 0.01 and 0.31 and 0.06–0.61, respectively. Based on the test results, a coupled damage model of the flawed rock under the combined action of FT cycles and impact loads is proposed, and then a dynamic damage constitutive model is established and verified accordingly, effectively characterizing the dynamic mechanical response of rocks with different FT cycles, flaw inclination angles, and filling states. Based on the principles of stress wave propagation and fracture mechanics, the filling reinforcement effect of rocks was explored. The filling material reduces the reflection of stress waves at the crack interface, enhances the propagation of stress waves, and thus reduces the adverse effects of impact loads on rocks. In addition, the filling material improves the uniformity of stress distribution at the crack tip, increases the stress intensity factor, and significantly enhances the bearing capacity of the rock. The filling effect depends on the matching of mechanical properties between the material and the rock. Therefore, when selecting filling materials, it is necessary to consider whether their FT degradation laws correspond to the rocks that need to be reinforced. The results contribute to clarifying the dynamic mechanical properties of flawed rocks in cold regions, providing guidance for the selection of filling materials and the reinforcement of fractured rock masses.
{"title":"Dynamic response and damage constitutive model of freeze-thawed sandstone with or without filling materials in prefabricated flaws","authors":"Chunyang Zhang , Tao Tan , Wenquan Duan , Wanru Li , Kaibin Hu , Jian Liao","doi":"10.1016/j.conbuildmat.2025.140435","DOIUrl":"10.1016/j.conbuildmat.2025.140435","url":null,"abstract":"<div><div>In cold regions, flawed rocks are inevitably affected by freeze-thaw (FT) weathering and dynamic impact, and grouting or filling has become an effective means to improve their stability. In order to clarify the mechanical properties of flawed rocks with or without filling materials under dynamic loading, a series of FT cycle tests and impact tests were conducted on sandstone. The results indicate that the number of FT cycles significantly deteriorates the dynamic peak strength, apparent stiffness, and energy parameters, which are strongly correlated with the flaw inclination angle. In addition, the mechanical properties and energy absorption capacity of the filled specimens were significantly improved, but were affected by the number of FT cycles and flaw inclination angle. The strength and energy enhancement coefficients of all specimens are between 0.01 and 0.31 and 0.06–0.61, respectively. Based on the test results, a coupled damage model of the flawed rock under the combined action of FT cycles and impact loads is proposed, and then a dynamic damage constitutive model is established and verified accordingly, effectively characterizing the dynamic mechanical response of rocks with different FT cycles, flaw inclination angles, and filling states. Based on the principles of stress wave propagation and fracture mechanics, the filling reinforcement effect of rocks was explored. The filling material reduces the reflection of stress waves at the crack interface, enhances the propagation of stress waves, and thus reduces the adverse effects of impact loads on rocks. In addition, the filling material improves the uniformity of stress distribution at the crack tip, increases the stress intensity factor, and significantly enhances the bearing capacity of the rock. The filling effect depends on the matching of mechanical properties between the material and the rock. Therefore, when selecting filling materials, it is necessary to consider whether their FT degradation laws correspond to the rocks that need to be reinforced. The results contribute to clarifying the dynamic mechanical properties of flawed rocks in cold regions, providing guidance for the selection of filling materials and the reinforcement of fractured rock masses.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"467 ","pages":"Article 140435"},"PeriodicalIF":7.4,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421564","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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