Pub Date : 2026-02-09DOI: 10.1016/j.jobe.2026.115581
Jian Yang, Jieqiong Wu, Liu Jin, Xiuli Du
To investigate the bond performance between steel/BFRP bar and concrete under low-temperature freeze-thaw and chloride attack, 72 specimens were subjected to the bond test, and a refined 3D bond model was developed, which explicitly incorporated bar surface geometry and freeze-thaw induced concrete deterioration. The results show that: (1) For thick concrete covers (≥70 mm), the failure mode is mainly determined by bar diameter, not freeze-thaw cycles. However, for BFRP specimens with thin covers (≤40 mm), the failure mode changes from pull-out to splitting failure after 200 cycles. (2) Bond strength decreases with increasing freeze-thaw cycles and bar diameter, but increases with concrete cover thickness. Steel bar specimens exhibit more severe bond degradation than BFRP bar specimens. (3) Peak slip decreases with freeze-thaw cycles but increases with bar diameter and cover thickness. (4) Increasing concrete cover thickness significantly mitigates the degradation effects of freeze-thaw on both bond strength and peak slip. Based on the experimental and simulated results, a bond stress-slip model incorporating the effects of low-temperature freeze-thaw cycles and cover-to-diameter ratio is proposed and validated.
{"title":"Study on the bond performance between steel/BFRP bar and concrete considering diameter, concrete cover thickness and low-temperature freeze-thaw","authors":"Jian Yang, Jieqiong Wu, Liu Jin, Xiuli Du","doi":"10.1016/j.jobe.2026.115581","DOIUrl":"https://doi.org/10.1016/j.jobe.2026.115581","url":null,"abstract":"To investigate the bond performance between steel/BFRP bar and concrete under low-temperature freeze-thaw and chloride attack, 72 specimens were subjected to the bond test, and a refined 3D bond model was developed, which explicitly incorporated bar surface geometry and freeze-thaw induced concrete deterioration. The results show that: (1) For thick concrete covers (≥70 mm), the failure mode is mainly determined by bar diameter, not freeze-thaw cycles. However, for BFRP specimens with thin covers (≤40 mm), the failure mode changes from pull-out to splitting failure after 200 cycles. (2) Bond strength decreases with increasing freeze-thaw cycles and bar diameter, but increases with concrete cover thickness. Steel bar specimens exhibit more severe bond degradation than BFRP bar specimens. (3) Peak slip decreases with freeze-thaw cycles but increases with bar diameter and cover thickness. (4) Increasing concrete cover thickness significantly mitigates the degradation effects of freeze-thaw on both bond strength and peak slip. Based on the experimental and simulated results, a bond stress-slip model incorporating the effects of low-temperature freeze-thaw cycles and cover-to-diameter ratio is proposed and validated.","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":"30 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-02-09DOI: 10.1016/j.jobe.2026.115587
João Victor da Cunha-Oliveira, Frankslale Fabian Diniz de Andrade Meira, Leila Soares Viegas Barreto Chagas, André Luiz Fiquene de Brito, Romualdo Rodrigues Menezes, Gelmires de Araújo Neves
This study presents a novel, low-carbon alternative for sewage sludge valorization by investigating low-temperature dehydration treatment (160-240 °C) to produce a particulate material (filler) for ultra-high performance concrete (UHPC), replacing silica fume (2-8%). The treatment at 240 °C yielded a filler (DS240) with improved physicochemical characteristics, including higher specific gravity (2.57 g/cm3), lower loss on ignition (20.7%), and higher BET surface area (9.43 m2/g), alongside the reduction of O–H and N–H groups and the formation of aliphatic structures. Simultaneous increases of 7.6% in workability and 9.7% in 28-day compressive strength were observed in UHPC-6%, while alkalinity remained constant across all compositions. Particle packing analysis showed that DS240 favored the mechanical performance improvement through its micro-filling effect. Furthermore, TCLP leaching tests confirmed that the UHPC-8% composite fully complied with the regulatory limits for the evaluated heavy metals (Cd, Pb, As and Se). Microstructurally, DS240 modified the hydration kinetics, delaying precipitation of C-S-H and portlandite and induced the crystallization of AFt and long-chain Q4 polymerized silicates. Moreover, the filler favored the formation of C-Ᾱ-S-H phases through the dissolution of aluminates. These effects resulted in strengths exceeding 200 MPa in all compositions. Additionally, the assessment through the Empathetic Added Sustainability Index (EASI) quantified a 9.5% gain in the overall sustainability of UHPC-6% compared to UHPC-0%. Therefore, low-temperature dehydration converts sewage sludge into a UHPC filler that improves performance and sustainability with regulatory immobilization (TCLP) of metals, validating its technical and environmental potential.
本研究通过研究低温脱水处理（160-240°C）来生产一种用于超高性能混凝土（UHPC）的颗粒材料（填料），取代硅灰（2-8%），提出了一种新的低碳污水污泥固化替代方案。在240°C下处理得到的填料（DS240）具有改善的物理化学特性，包括更高的比重（2.57 g/cm3），更低的着火损失（20.7%），更高的BET表面积（9.43 m2/g），以及O-H和N-H基团的减少和脂肪族结构的形成。在UHPC-6%中，可加工性同时增加7.6%，28天抗压强度同时增加9.7%，而所有成分的碱度保持不变。颗粒充填分析表明，DS240的微填充效应有利于力学性能的提高。此外，TCLP浸出试验证实，UHPC-8%复合材料完全符合评估重金属（Cd, Pb， As和Se）的法规限值。微观结构上，DS240改变了水化动力学，延缓了C-S-H和硅酸盐的沉淀，诱导了AFt和长链Q4聚合硅酸盐的结晶。此外，填料有利于通过铝酸盐的溶解形成C-Ᾱ- s - h相。这些影响导致所有成分的强度都超过200mpa。此外，通过移情附加可持续性指数（EASI）进行的评估量化了uhpc的总体可持续性增长9.5% -6%，而uhpc为0%。因此，低温脱水将污水污泥转化为UHPC填料，通过金属的调节固定化（TCLP）提高了性能和可持续性，验证了其技术和环境潜力。
{"title":"Low-temperature treated sewage sludge as filler for ultra-high performance concrete application","authors":"João Victor da Cunha-Oliveira, Frankslale Fabian Diniz de Andrade Meira, Leila Soares Viegas Barreto Chagas, André Luiz Fiquene de Brito, Romualdo Rodrigues Menezes, Gelmires de Araújo Neves","doi":"10.1016/j.jobe.2026.115587","DOIUrl":"https://doi.org/10.1016/j.jobe.2026.115587","url":null,"abstract":"This study presents a novel, low-carbon alternative for sewage sludge valorization by investigating low-temperature dehydration treatment (160-240 °C) to produce a particulate material (filler) for ultra-high performance concrete (UHPC), replacing silica fume (2-8%). The treatment at 240 °C yielded a filler (DS240) with improved physicochemical characteristics, including higher specific gravity (2.57 g/cm<ce:sup loc=\"post\">3</ce:sup>), lower loss on ignition (20.7%), and higher BET surface area (9.43 m<ce:sup loc=\"post\">2</ce:sup>/g), alongside the reduction of O–H and N–H groups and the formation of aliphatic structures. Simultaneous increases of 7.6% in workability and 9.7% in 28-day compressive strength were observed in UHPC-6%, while alkalinity remained constant across all compositions. Particle packing analysis showed that DS240 favored the mechanical performance improvement through its micro-filling effect. Furthermore, TCLP leaching tests confirmed that the UHPC-8% composite fully complied with the regulatory limits for the evaluated heavy metals (Cd, Pb, As and Se). Microstructurally, DS240 modified the hydration kinetics, delaying precipitation of C-S-H and portlandite and induced the crystallization of AFt and long-chain Q<ce:inf loc=\"post\">4</ce:inf> polymerized silicates. Moreover, the filler favored the formation of C-Ᾱ-S-H phases through the dissolution of aluminates. These effects resulted in strengths exceeding 200 MPa in all compositions. Additionally, the assessment through the Empathetic Added Sustainability Index (EASI) quantified a 9.5% gain in the overall sustainability of UHPC-6% compared to UHPC-0%. Therefore, low-temperature dehydration converts sewage sludge into a UHPC filler that improves performance and sustainability with regulatory immobilization (TCLP) of metals, validating its technical and environmental potential.","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":"33 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146600","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-02-09DOI: 10.1016/j.jobe.2026.115546
Cheng Hu, Xujian Lin, Xin Li, Haosheng Jiang, Tao Ji
Magnesium silicon potassium phosphate cement (MgO-K2HPO4-SiO2, MSPPC) is a new high-performance magnesium-based cementitious material distinguished from traditional magnesium phosphate cement (MPC). Compared with MPC, MSPPC exhibits superior mechanical properties and broader application prospects; however, its strength degradation under long-term water exposure limits its durability in rapid-repair and emergency construction projects. To improve its water resistance, this study introduces montmorillonite (Mt), which possesses excellent adsorption capacity, cation-exchange ability, and dispersion performance, as a synergistic modifier on the basis of 10% slag incorporation. The effects of different Mt contents (0.25%, 0.50%, 0.75%, and 1.00%) on the water-curing performance of MSPPC are systematically investigated. The pore structure evolution and water-stability mechanisms of hydration products are analyzed through multiple micro-characterization techniques, including XRD, SEM-EDS, MIP, and TG-DSC. The results indicate that an appropriate Mt content effectively enhances the structural stability and strength retention of MSPPC in humid environments. When the Mt content reaches 1.00%, the 90 d compressive strength retention ratio reaches 92.69%, although the absolute compressive strength decreases slightly. When the Mt content is 0.50%, the total porosity is the lowest (5.72%), and the pore size distribution becomes significantly refined, contributing to the formation of a dense matrix. Microstructural analyses reveal that montmorillonite optimizes the particle packing, promotes the formation and recrystallization of MKP and related hydration products, and constructs an interwoven spatial network of crystalline and gel phases, thereby simultaneously enhancing pore refinement and hydration-product stability. This study elucidates the synergistic mechanism by which montmorillonite drives microstructural evolution and improves water resistance in MSPPC, providing theoretical support and technical references for the design and engineering application of highly water-resistant magnesium-based cementitious materials.
{"title":"Mechanism of Microstructural Evolution and Water-Resistance Improvement Driven by Montmorillonite in MgO-K2HPO4-SiO2 Cement Systems","authors":"Cheng Hu, Xujian Lin, Xin Li, Haosheng Jiang, Tao Ji","doi":"10.1016/j.jobe.2026.115546","DOIUrl":"https://doi.org/10.1016/j.jobe.2026.115546","url":null,"abstract":"Magnesium silicon potassium phosphate cement (MgO-K<ce:inf loc=\"post\">2</ce:inf>HPO<ce:inf loc=\"post\">4</ce:inf>-SiO<ce:inf loc=\"post\">2</ce:inf>, MSPPC) is a new high-performance magnesium-based cementitious material distinguished from traditional magnesium phosphate cement (MPC). Compared with MPC, MSPPC exhibits superior mechanical properties and broader application prospects; however, its strength degradation under long-term water exposure limits its durability in rapid-repair and emergency construction projects. To improve its water resistance, this study introduces montmorillonite (Mt), which possesses excellent adsorption capacity, cation-exchange ability, and dispersion performance, as a synergistic modifier on the basis of 10% slag incorporation. The effects of different Mt contents (0.25%, 0.50%, 0.75%, and 1.00%) on the water-curing performance of MSPPC are systematically investigated. The pore structure evolution and water-stability mechanisms of hydration products are analyzed through multiple micro-characterization techniques, including XRD, SEM-EDS, MIP, and TG-DSC. The results indicate that an appropriate Mt content effectively enhances the structural stability and strength retention of MSPPC in humid environments. When the Mt content reaches 1.00%, the 90 d compressive strength retention ratio reaches 92.69%, although the absolute compressive strength decreases slightly. When the Mt content is 0.50%, the total porosity is the lowest (5.72%), and the pore size distribution becomes significantly refined, contributing to the formation of a dense matrix. Microstructural analyses reveal that montmorillonite optimizes the particle packing, promotes the formation and recrystallization of MKP and related hydration products, and constructs an interwoven spatial network of crystalline and gel phases, thereby simultaneously enhancing pore refinement and hydration-product stability. This study elucidates the synergistic mechanism by which montmorillonite drives microstructural evolution and improves water resistance in MSPPC, providing theoretical support and technical references for the design and engineering application of highly water-resistant magnesium-based cementitious materials.","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":"93 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study systematically investigates the reaction kinetics, phase assemblage, and microstructural evolution of alkali-activated magnesium slag and steel slag to address the challenges associated with their valorization due to distinct reactivity. The results reveal that intrinsic compositional differences govern their reaction pathways. The steel slag-based system exhibits high reactivity, forming a complex network of C-A-S-H, layered double hydroxides (LDH), strätlingite, and hydrogarnet. Alkalinity plays a critical role in phase selection. Lower alkalinity favors LDH and hydrogarnet, whereas higher alkalinity promotes strätlingite and rapidly develops a dense, high-strength matrix, reaching a 28-day compressive strength of 21.8 MPa. In contrast, the magnesium slag-based system requires higher alkalinity to form C-A-S-H and M-S-H gels due to its content of stable γ-C2S and periclase. However, high alkalinity triggers expansive hydration of periclase, impairing network integrity and limiting strength gain, and finally resulting in a lower 28-day strength of 8.0 MPa. While both binders effectively immobilize heavy metals, the steel slag system achieves a superior balance of mechanical performance and eco-efficiency at lower alkali dosages. Conversely, the high activator dosage required for magnesium slag is less cost-effective due to diminishing performance returns. This work clarifies the mechanistic divergence between these metallurgical wastes, offering essential guidance for designing sustainable, waste-based binders tailored to specific slag characteristics.
{"title":"Alkali-activated magnesium slag and steel slag materials: Insights into reaction behavior, microstructure evolution, and performance development","authors":"Yumei Nong, MiaoMiao Zhu, Ruoxin Zhai, Mingming Zhu, Yutao Guo, Ruiquan Jia, Jianwei Sun, Zihan Zhou, Shiyu Zhuang","doi":"10.1016/j.jobe.2026.115393","DOIUrl":"https://doi.org/10.1016/j.jobe.2026.115393","url":null,"abstract":"This study systematically investigates the reaction kinetics, phase assemblage, and microstructural evolution of alkali-activated magnesium slag and steel slag to address the challenges associated with their valorization due to distinct reactivity. The results reveal that intrinsic compositional differences govern their reaction pathways. The steel slag-based system exhibits high reactivity, forming a complex network of C-A-S-H, layered double hydroxides (LDH), strätlingite, and hydrogarnet. Alkalinity plays a critical role in phase selection. Lower alkalinity favors LDH and hydrogarnet, whereas higher alkalinity promotes strätlingite and rapidly develops a dense, high-strength matrix, reaching a 28-day compressive strength of 21.8 MPa. In contrast, the magnesium slag-based system requires higher alkalinity to form C-A-S-H and M-S-H gels due to its content of stable γ-C<ce:inf loc=\"post\">2</ce:inf>S and periclase. However, high alkalinity triggers expansive hydration of periclase, impairing network integrity and limiting strength gain, and finally resulting in a lower 28-day strength of 8.0 MPa. While both binders effectively immobilize heavy metals, the steel slag system achieves a superior balance of mechanical performance and eco-efficiency at lower alkali dosages. Conversely, the high activator dosage required for magnesium slag is less cost-effective due to diminishing performance returns. This work clarifies the mechanistic divergence between these metallurgical wastes, offering essential guidance for designing sustainable, waste-based binders tailored to specific slag characteristics.","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":"2 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146146683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Field test research on the uniformity of deep cement mixing columns based on macroscopic mechanics and microporous structure","authors":"Weilong Qin, Yu Wan, Jingchen Xie, Dingwen Zhang, Fengcheng Wang, Shengjie Lu","doi":"10.1016/j.jobe.2026.115512","DOIUrl":"https://doi.org/10.1016/j.jobe.2026.115512","url":null,"abstract":"","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":"91 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146138289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-02-08DOI: 10.1016/j.jobe.2026.115542
Gangchuan Xie, Jingwei Gong, Yizhou Tang, Zhejun Su, Kebin Shi
{"title":"Roles of alkalinity and carbonate ions concentration of carbonated carbide slag solution in hydration-carbonation kinetics of low-heat Portland cement","authors":"Gangchuan Xie, Jingwei Gong, Yizhou Tang, Zhejun Su, Kebin Shi","doi":"10.1016/j.jobe.2026.115542","DOIUrl":"https://doi.org/10.1016/j.jobe.2026.115542","url":null,"abstract":"","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":"72 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146138287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-02-08DOI: 10.1016/j.jobe.2026.115539
Sang-Woo Kim, Sunho Lee, Jung-Yoon Lee
{"title":"Shear Strength Reduction in Reinforced Concrete Deep Beams with Different Soffit Offset Ratios under Indirect Loading","authors":"Sang-Woo Kim, Sunho Lee, Jung-Yoon Lee","doi":"10.1016/j.jobe.2026.115539","DOIUrl":"https://doi.org/10.1016/j.jobe.2026.115539","url":null,"abstract":"","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":"4 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146138292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-02-08DOI: 10.1016/j.jobe.2026.115536
Shuai Song, Xiangyun Xu, Wangjun Ren, Bin Guo
{"title":"Strain Rate Effects on Damage Similarity in Scaled RC Frames under Internal Explosion and Its Correction Method","authors":"Shuai Song, Xiangyun Xu, Wangjun Ren, Bin Guo","doi":"10.1016/j.jobe.2026.115536","DOIUrl":"https://doi.org/10.1016/j.jobe.2026.115536","url":null,"abstract":"","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":"92 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146138290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2026-02-08DOI: 10.1016/j.jobe.2026.115532
Yu Deng, Runhua Bao, Yihui Ying
{"title":"Experimental study on the mechanical properties of rectangular CFST members under bidirectional eccentric tensile loading","authors":"Yu Deng, Runhua Bao, Yihui Ying","doi":"10.1016/j.jobe.2026.115532","DOIUrl":"https://doi.org/10.1016/j.jobe.2026.115532","url":null,"abstract":"","PeriodicalId":15064,"journal":{"name":"Journal of building engineering","volume":"23 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146138291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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