Pub Date : 2025-02-15DOI: 10.1016/j.conbuildmat.2025.140392
Xiongfei Liu , Chuang Li , Pei Guo , Li Wang , Jinnan Chen , Guowei Ma , Qiao Wang
A spray-based 3D (S-3D) printed tunnel slag concrete material is developed in this paper. The effects of tunnel slag as fine aggregate, with replacement rates of 0 %, 60 %, 80 %, 100 %, and 120 %, on the workability, printability, and mechanical properties of the S-3D printed concrete are systematically investigated. The hydration process of the printed concrete is further analyzed by SEM, XRD, and X-CT. The test results demonstrate that the fine particles and stone powder in the tunnel slag, along with its rough texture, significantly optimize the rheological property of the concrete. The concrete with 100 % tunnel slag exhibits optimal thixotropy, printing accuracy, and buildability, along with enhanced mechanical properties. The compressive, flexural, and interlayer splitting strengths of the S-3D printed concrete with 100 % tunnel slag at 28 d increased by 8.84 %, 7.69 %, and 8.72 %, respectively, compared to the printed concrete without tunnel slag, achieving maximum strengths of 77.6 MPa, 14.0 MPa, and 2.12 MPa. The rough surface of the tunnel slag also facilitates stronger interface bonding with the cementitious materials. Additionally, combined with the effect of S-3D printing process, the S-3D printed concrete with 100 % tunnel slag shows a minimum porosity, decreased by 41.30 % compared to the printed concrete without tunnel slag. A tunnel lining structure model is successfully printed using the optimal 100 % tunnel slag concrete, demonstrating a novel approach to the resource utilization of tunnel slag and its application in intelligent lining construction.
{"title":"Spray-based 3D printed tunnel slag concrete: Evaluation for printability and mechanical performance","authors":"Xiongfei Liu , Chuang Li , Pei Guo , Li Wang , Jinnan Chen , Guowei Ma , Qiao Wang","doi":"10.1016/j.conbuildmat.2025.140392","DOIUrl":"10.1016/j.conbuildmat.2025.140392","url":null,"abstract":"<div><div>A spray-based 3D (S-3D) printed tunnel slag concrete material is developed in this paper. The effects of tunnel slag as fine aggregate, with replacement rates of 0 %, 60 %, 80 %, 100 %, and 120 %, on the workability, printability, and mechanical properties of the S-3D printed concrete are systematically investigated. The hydration process of the printed concrete is further analyzed by SEM, XRD, and X-CT. The test results demonstrate that the fine particles and stone powder in the tunnel slag, along with its rough texture, significantly optimize the rheological property of the concrete. The concrete with 100 % tunnel slag exhibits optimal thixotropy, printing accuracy, and buildability, along with enhanced mechanical properties. The compressive, flexural, and interlayer splitting strengths of the S-3D printed concrete with 100 % tunnel slag at 28 d increased by 8.84 %, 7.69 %, and 8.72 %, respectively, compared to the printed concrete without tunnel slag, achieving maximum strengths of 77.6 MPa, 14.0 MPa, and 2.12 MPa. The rough surface of the tunnel slag also facilitates stronger interface bonding with the cementitious materials. Additionally, combined with the effect of S-3D printing process, the S-3D printed concrete with 100 % tunnel slag shows a minimum porosity, decreased by 41.30 % compared to the printed concrete without tunnel slag. A tunnel lining structure model is successfully printed using the optimal 100 % tunnel slag concrete, demonstrating a novel approach to the resource utilization of tunnel slag and its application in intelligent lining construction.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"467 ","pages":"Article 140392"},"PeriodicalIF":7.4,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421609","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 : 2025-02-15DOI: 10.1016/j.conbuildmat.2025.140366
Yougui Luo , Haitao Li , Haitao Ke , Pin Zhou , Ottavia Corbi , Ileana Corbi
To facilitate the application of high-performance wood scrimber in the construction engineering field, this experiment designed tests for the mechanical properties of eucalyptus wood scrimber under tension, compression, bending, and shear. It also analyzed the failure mode, load-displacement curve, and stress-strain curve. The results indicated that the stress-strain model of scrimber under compression, tension, and shear was established based on the Ramberg-Osgood relationship. The modulus and poisson ratio were analyzed, and it was found that the eucalyptus scrimber could be approximately regarded as an orthotropic material. Its ductility coefficient is 2.2, making it suitable for use as a seismic design material for timber structures. When compared with the basic mechanical properties of other engineering wood and bamboo materials, the eucalyptus scrimber can be used as a substitute for them due to its high strength.
{"title":"Research on the basic mechanical properties of eucalyptus wood scrimber","authors":"Yougui Luo , Haitao Li , Haitao Ke , Pin Zhou , Ottavia Corbi , Ileana Corbi","doi":"10.1016/j.conbuildmat.2025.140366","DOIUrl":"10.1016/j.conbuildmat.2025.140366","url":null,"abstract":"<div><div>To facilitate the application of high-performance wood scrimber in the construction engineering field, this experiment designed tests for the mechanical properties of eucalyptus wood scrimber under tension, compression, bending, and shear. It also analyzed the failure mode, load-displacement curve, and stress-strain curve. The results indicated that the stress-strain model of scrimber under compression, tension, and shear was established based on the Ramberg-Osgood relationship. The modulus and poisson ratio were analyzed, and it was found that the eucalyptus scrimber could be approximately regarded as an orthotropic material. Its ductility coefficient is 2.2, making it suitable for use as a seismic design material for timber structures. When compared with the basic mechanical properties of other engineering wood and bamboo materials, the eucalyptus scrimber can be used as a substitute for them due to its high strength.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"467 ","pages":"Article 140366"},"PeriodicalIF":7.4,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421613","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 : 2025-02-15DOI: 10.1016/j.conbuildmat.2025.140390
Bin Wang , Qi Niu , Peng Chen , Zhanhong Zhang , Theodore L. Karavasilis
Seismic isolation technology typically protects superstructures by incorporating isolation bearings between the superstructure and the foundation. The isolation system extends the natural period of the structure and provides additional damping, effectively dissipating earthquake-induced energy during strong earthquakes. Among the commonly used bearings, high-damping rubber bearings (HDRBs) have emerged as a preferred solution due to the inherent energy dissipation capability. However, during near-fault strong earthquakes, isolation bearings are prone to experiencing large strains. Previous studies have paid little attention to the large strain responses of HDRBs under various loading conditions, which significantly differ from their hysteresis properties under moderate shear strain loading. To address this gap, this study experimentally and numerically investigated the hysteretic responses of four full-scale HDRBs under large cyclic strains of up to 400 %. Test results indicate that the mechanical properties of HDRBs are significantly influenced by strain levels and loading protocols. The HDRBs exhibit pronounced nonlinearity in their shear force–strain relationships. Notably, as shear strain exceeds 200 %, the HDRBs demonstrate significant nonlinear hardening, strength degradation, and unloading effects. The hardening stiffness of the HDRBs is considerably higher than the post-yield stiffness. Furthermore, HDRBs show substantial variations in peak strength and degradation characteristics under different loading protocols. A numerical strategy was also developed to further explore the deformation mechanisms of the HDRBs under large strain loading conditions.
{"title":"Experimental and numerical investigations on mechanical properties of high-damping rubber bearings under large strain loading","authors":"Bin Wang , Qi Niu , Peng Chen , Zhanhong Zhang , Theodore L. Karavasilis","doi":"10.1016/j.conbuildmat.2025.140390","DOIUrl":"10.1016/j.conbuildmat.2025.140390","url":null,"abstract":"<div><div>Seismic isolation technology typically protects superstructures by incorporating isolation bearings between the superstructure and the foundation. The isolation system extends the natural period of the structure and provides additional damping, effectively dissipating earthquake-induced energy during strong earthquakes. Among the commonly used bearings, high-damping rubber bearings (HDRBs) have emerged as a preferred solution due to the inherent energy dissipation capability. However, during near-fault strong earthquakes, isolation bearings are prone to experiencing large strains. Previous studies have paid little attention to the large strain responses of HDRBs under various loading conditions, which significantly differ from their hysteresis properties under moderate shear strain loading. To address this gap, this study experimentally and numerically investigated the hysteretic responses of four full-scale HDRBs under large cyclic strains of up to 400 %. Test results indicate that the mechanical properties of HDRBs are significantly influenced by strain levels and loading protocols. The HDRBs exhibit pronounced nonlinearity in their shear force–strain relationships. Notably, as shear strain exceeds 200 %, the HDRBs demonstrate significant nonlinear hardening, strength degradation, and unloading effects. The hardening stiffness of the HDRBs is considerably higher than the post-yield stiffness. Furthermore, HDRBs show substantial variations in peak strength and degradation characteristics under different loading protocols. A numerical strategy was also developed to further explore the deformation mechanisms of the HDRBs under large strain loading conditions.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"467 ","pages":"Article 140390"},"PeriodicalIF":7.4,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421636","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 : 2025-02-15DOI: 10.1016/j.conbuildmat.2025.140365
Jun Yang , Zhao Zheng , Xinpeng Ye , Jiahui Guo , Yongxin Fu , Kang Wang , Qian Liu , Bo Wu , Xue Ma , Hao Deng , Yuxiang Li
In order to investigate the changes in pore structure, C-S-H gel structure, and its products in carbonated and non-carbonated airport pavement concrete under freeze-thaw cycles induced by airport deicers, this study examined the single-sided freeze-thaw damage of concrete exposed to five different airport deicers with a mass concentration of 3 %: potassium formate (PF), commercial potassium formate (PF-C), potassium acetate (PA), commercial potassium acetate (PA-C), and calcium magnesium acetate (CMA).Quantitative characterization techniques such as XPS NMR, and MIP were employed to evaluate the relevant parameters. The results show that carbonation improves the freeze-thaw resistance of concrete by reducing the porosity of the concrete surface layer, enhancing the polymerization degree of C-S-H gel, and increasing the Ca/Si ratio. During the freeze-thaw cycles, when carbonated or non-carbonated concrete was exposed to PF and PF-C, the harmful pores in the surface debris increased significantly, and spalling was more likely to occur in the cement paste layer with a low Ca/Si ratio, ultimately leading to more severe freeze-thaw damage. In contrast, CMA had the least impact on freeze-thaw damage. These findings provide practical insights for selecting suitable deicers and optimizing carbonation treatment to improve the durability of airport pavement concrete in cold climates.
{"title":"Damage mechanism of airport pavement concrete undergoing freeze-thaw: The coupling effects of low-concentration deicers and carbonation","authors":"Jun Yang , Zhao Zheng , Xinpeng Ye , Jiahui Guo , Yongxin Fu , Kang Wang , Qian Liu , Bo Wu , Xue Ma , Hao Deng , Yuxiang Li","doi":"10.1016/j.conbuildmat.2025.140365","DOIUrl":"10.1016/j.conbuildmat.2025.140365","url":null,"abstract":"<div><div>In order to investigate the changes in pore structure, C-S-H gel structure, and its products in carbonated and non-carbonated airport pavement concrete under freeze-thaw cycles induced by airport deicers, this study examined the single-sided freeze-thaw damage of concrete exposed to five different airport deicers with a mass concentration of 3 %: potassium formate (PF), commercial potassium formate (PF-C), potassium acetate (PA), commercial potassium acetate (PA-C), and calcium magnesium acetate (CMA).Quantitative characterization techniques such as XPS NMR, and MIP were employed to evaluate the relevant parameters. The results show that carbonation improves the freeze-thaw resistance of concrete by reducing the porosity of the concrete surface layer, enhancing the polymerization degree of C-S-H gel, and increasing the Ca/Si ratio. During the freeze-thaw cycles, when carbonated or non-carbonated concrete was exposed to PF and PF-C, the harmful pores in the surface debris increased significantly, and spalling was more likely to occur in the cement paste layer with a low Ca/Si ratio, ultimately leading to more severe freeze-thaw damage. In contrast, CMA had the least impact on freeze-thaw damage. These findings provide practical insights for selecting suitable deicers and optimizing carbonation treatment to improve the durability of airport pavement concrete in cold climates.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"467 ","pages":"Article 140365"},"PeriodicalIF":7.4,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421715","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 : 2025-02-15DOI: 10.1016/j.conbuildmat.2025.140410
Chao-qiang Wang , Shen Chen , Bo-wen Wen , Yuan-chun Zhang , Kai Wu
Red mud(RM) and fly ash(FA) are solid wastes generated by the alumina industry and phosphate chemical enterprises during the production of alumina and phosphoric acid, respectively. Their large-scale harmless and resource utilization is of great significance. In this study, advanced scientific testing techniques and research methods were used to prepare cementitious materials and no-fire ceramic granules from solid wastes such as RM, FA and phosphogypsum(PG), which were used to prepare road base materials, and to investigate the mix design, hydration mechanism, and heavy metal migration behavior.The results showed that the optimum mix proportion for red mud-fly ash cementitious materials(RFCM) was determined as follows:RM 40.79 %, FA 36.89 %, PG 17.47 %, PC 4.85 %, and superplasticizer dosage at 1.7 % of the binder material. Under a water-to-binder ratio of 0.18, after 28 days of curing, the flexural strength was 3.6 MPa, and the compressive strength was 26.9 MPa. Based on soil environmental and human health risk assessment results, Cr had carcinogenic risks, while more attention was needed on the risks of Hg, Cd, and Pb. Thus, this study identified Cr, Cd, Hg, and Pb as characteristic heavy metals(HMs). Using the optimal mix proportion of the RFCM as a basis, the optimal mix proportion of unburned ceramsite was determined as follows: RM 22.74 %, FA 20.56 %, PG 9.74 %, PC 2.7 %, and river sand 44.26 %. The density grade of the unburned ceramsite was 600, meeting the requirements of "Lightweight aggregates and its test methods-Part 1: Lightweight aggregates" (GB/T 17431.1–2010) for bulk density, cylinder compressive strength, and water absorption. Substituting aggregates with equal particle sizes for red mud-fly ash based road base materials(RFRBM) and designing the mix proportion for RFRBM, the mix ratio of base course aggregates was 20–30 mm: 10–20 mm: 5–10 mm (unburned ceramsite): 0–5 mm = 17.3: 34.8: 24.5: 23.5, with an optimal dosage of binder material at 12 %. The specimens could meet the requirements of "Technical guidelines for construction of highway roadbases" (JTG/T F20–2015) for unconfined compressive strength and splitting tensile strength. At the same time, the durability of RFGFM was tested and analysed with reference to the standard. Utilizing leaching kinetic models analyzed the leaching behavior of characteristic HMs in the base course system and constructed a risk control system for HMs in RFRBM. Finally, reference limits for HMs were proposed according to the application scenarios of RFRBM.
{"title":"Red mud modified fly ash based road base materials: Mix design, hydration mechanism, and heavy metal migration behavior","authors":"Chao-qiang Wang , Shen Chen , Bo-wen Wen , Yuan-chun Zhang , Kai Wu","doi":"10.1016/j.conbuildmat.2025.140410","DOIUrl":"10.1016/j.conbuildmat.2025.140410","url":null,"abstract":"<div><div>Red mud(RM) and fly ash(FA) are solid wastes generated by the alumina industry and phosphate chemical enterprises during the production of alumina and phosphoric acid, respectively. Their large-scale harmless and resource utilization is of great significance. In this study, advanced scientific testing techniques and research methods were used to prepare cementitious materials and no-fire ceramic granules from solid wastes such as RM, FA and phosphogypsum(PG), which were used to prepare road base materials, and to investigate the mix design, hydration mechanism, and heavy metal migration behavior.The results showed that the optimum mix proportion for red mud-fly ash cementitious materials(RFCM) was determined as follows:RM 40.79 %, FA 36.89 %, PG 17.47 %, PC 4.85 %, and superplasticizer dosage at 1.7 % of the binder material. Under a water-to-binder ratio of 0.18, after 28 days of curing, the flexural strength was 3.6 MPa, and the compressive strength was 26.9 MPa. Based on soil environmental and human health risk assessment results, Cr had carcinogenic risks, while more attention was needed on the risks of Hg, Cd, and Pb. Thus, this study identified Cr, Cd, Hg, and Pb as characteristic heavy metals(HMs). Using the optimal mix proportion of the RFCM as a basis, the optimal mix proportion of unburned ceramsite was determined as follows: RM 22.74 %, FA 20.56 %, PG 9.74 %, PC 2.7 %, and river sand 44.26 %. The density grade of the unburned ceramsite was 600, meeting the requirements of \"Lightweight aggregates and its test methods-Part 1: Lightweight aggregates\" (GB/T 17431.1–2010) for bulk density, cylinder compressive strength, and water absorption. Substituting aggregates with equal particle sizes for red mud-fly ash based road base materials(RFRBM) and designing the mix proportion for RFRBM, the mix ratio of base course aggregates was 20–30 mm: 10–20 mm: 5–10 mm (unburned ceramsite): 0–5 mm = 17.3: 34.8: 24.5: 23.5, with an optimal dosage of binder material at 12 %. The specimens could meet the requirements of \"Technical guidelines for construction of highway roadbases\" (JTG/T F20–2015) for unconfined compressive strength and splitting tensile strength. At the same time, the durability of RFGFM was tested and analysed with reference to the standard. Utilizing leaching kinetic models analyzed the leaching behavior of characteristic HMs in the base course system and constructed a risk control system for HMs in RFRBM. Finally, reference limits for HMs were proposed according to the application scenarios of RFRBM.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"467 ","pages":"Article 140410"},"PeriodicalIF":7.4,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421716","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 : 2025-02-15DOI: 10.1016/j.conbuildmat.2025.140415
Dongming Huang, Xinyu Chen, Zhenzhen Liu, Yiyan Lu, Shan Li
The geopolymer recycled aggregate concrete-filled glass fiber reinforced plastic (GFRP) tube (GRCFFT) column represents an eco-friendly composite solution; however, its initial compressive stiffness is inadequate, and its integration with other components presents challenges. H-shaped steel reinforcement was embedded into the GRCFFTs to address these issues, resulting in the development of the H-shaped steel-reinforced geopolymer recycled aggregate concrete-filled GFRP tube (SR-GRCFFT) column. This study investigated the effects of concrete core and GFRP tube parameters on the axial compression performance of SR-GRCFFT columns. The failure modes of the specimens, along with their load-displacement behavior and axial strain-hoop strain behavior, were analyzed. Furthermore, the enhancement effect of the H-shaped steel on the GRCFFT columns was quantified. The results indicated that the characteristics of the GFRP tube primarily dictated the failure modes exhibited by the SR-GRCFFT columns. Substituting 100 % RCA led to a 7.5 % decrease in bearing capacity, but adding 1.5 % steel fiber resulted in a 6.0 % increase. Notably, incorporating 6.45 % H-shaped steel improved the bearing capacity of the GRCFFTs by 23.9–40.6 % and enhanced the initial stiffness by 41.0–67.2 %. Furthermore, a synergistic effect was observed between the GFRP pipe and the H-shaped steel restraining the concrete. Finally, predictive models for the ultimate states of GRCFFTs were proposed, which considered the constrained stiffness ratio and a practical design formula for the bearing capacity of SR-GRCFFTs based on the superposition principle.
{"title":"Axial compressive behaviors of H-shaped steel-reinforced geopolymer recycled aggregate concrete-filled GFRP tube columns","authors":"Dongming Huang, Xinyu Chen, Zhenzhen Liu, Yiyan Lu, Shan Li","doi":"10.1016/j.conbuildmat.2025.140415","DOIUrl":"10.1016/j.conbuildmat.2025.140415","url":null,"abstract":"<div><div>The geopolymer recycled aggregate concrete-filled glass fiber reinforced plastic (GFRP) tube (GRCFFT) column represents an eco-friendly composite solution; however, its initial compressive stiffness is inadequate, and its integration with other components presents challenges. H-shaped steel reinforcement was embedded into the GRCFFTs to address these issues, resulting in the development of the H-shaped steel-reinforced geopolymer recycled aggregate concrete-filled GFRP tube (SR-GRCFFT) column. This study investigated the effects of concrete core and GFRP tube parameters on the axial compression performance of SR-GRCFFT columns. The failure modes of the specimens, along with their load-displacement behavior and axial strain-hoop strain behavior, were analyzed. Furthermore, the enhancement effect of the H-shaped steel on the GRCFFT columns was quantified. The results indicated that the characteristics of the GFRP tube primarily dictated the failure modes exhibited by the SR-GRCFFT columns. Substituting 100 % RCA led to a 7.5 % decrease in bearing capacity, but adding 1.5 % steel fiber resulted in a 6.0 % increase. Notably, incorporating 6.45 % H-shaped steel improved the bearing capacity of the GRCFFTs by 23.9–40.6 % and enhanced the initial stiffness by 41.0–67.2 %. Furthermore, a synergistic effect was observed between the GFRP pipe and the H-shaped steel restraining the concrete. Finally, predictive models for the ultimate states of GRCFFTs were proposed, which considered the constrained stiffness ratio and a practical design formula for the bearing capacity of SR-GRCFFTs based on the superposition principle.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"467 ","pages":"Article 140415"},"PeriodicalIF":7.4,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421634","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}
Iron-based shape memory alloys (Fe-SMAs) exhibit unique shape recovery and memory effect behavior upon thermal activation, making them advantageous for structural applications such as prestressing. Introducing short Fe-SMA fibers into concrete structures allows for a uniform and localized distribution of prestressing forces within the concrete matrix. In this study, an experimental campaign was conducted to evaluate the efficiency of prestressing concrete using short Fe-SMA fibers. Concrete prism specimens reinforced with randomly dispersed Fe-SMA fibers, steel fibers, and plain concrete reference specimens were tested under three-point bending after exposure to ambient temperature, 160 °C, and 200 °C. All fiber-reinforced specimens contained a targeted 2% volume fraction of fibers with identical geometries featuring end-hooked shapes for enhanced pull-out resistance. At ambient temperature, the Fe-SMA fibers remain in a passive, non-activated state and do not undergo the phase transformation required to generate prestressing forces. As a result, at ambient temperature, specimens with steel fibers show higher flexural strength (22.95 MPa) than those containing Fe-SMA fibers (20.2 MPa). However, when the prisms with Fe-SMA fibers are heated to 160 °C and 200 °C, they recover their pre-defined shape, which applies prestress to the surrounding concrete. This prestress increases the load-bearing capacity of the prism, leading to higher flexural strength in the Fe-SMA specimens (26.65 MPa and 24.39 MPa, respectively) compared to their steel–fiber counterparts (19.46 MPa and 16.67 MPa, respectively). Based on these findings, a numerical model was developed to simulate the behavior of concrete composites reinforced with randomly dispersed Fe-SMA fibers. An algorithm was created to define the random distribution of fibers, and a novel modeling approach accounted for the end-hooked geometry by assigning different contact properties to the modeled straight fiber ends and middle sections. A mesh sensitivity analysis was performed to determine the optimal mesh size, and the model was validated by comparing numerical results with experimental data. In summary, the key finding of this work is that thermally activated Fe-SMA fibers can effectively prestress concrete and enhance its flexural strength beyond that achievable with conventional steel fibers at ambient conditions.
{"title":"Prestressing of concrete using iron-based shape memory alloy (Fe-SMA) short fibers: Experimental and numerical analysis","authors":"Alireza Tabrizikahou , Mieczysław Kuczma , Zafiris Triantafyllidis , Moslem Shahverdi","doi":"10.1016/j.conbuildmat.2025.140309","DOIUrl":"10.1016/j.conbuildmat.2025.140309","url":null,"abstract":"<div><div>Iron-based shape memory alloys (Fe-SMAs) exhibit unique shape recovery and memory effect behavior upon thermal activation, making them advantageous for structural applications such as prestressing. Introducing short Fe-SMA fibers into concrete structures allows for a uniform and localized distribution of prestressing forces within the concrete matrix. In this study, an experimental campaign was conducted to evaluate the efficiency of prestressing concrete using short Fe-SMA fibers. Concrete prism specimens reinforced with randomly dispersed Fe-SMA fibers, steel fibers, and plain concrete reference specimens were tested under three-point bending after exposure to ambient temperature, 160 °C, and 200 °C. All fiber-reinforced specimens contained a targeted 2% volume fraction of fibers with identical geometries featuring end-hooked shapes for enhanced pull-out resistance. At ambient temperature, the Fe-SMA fibers remain in a passive, non-activated state and do not undergo the phase transformation required to generate prestressing forces. As a result, at ambient temperature, specimens with steel fibers show higher flexural strength (22.95 MPa) than those containing Fe-SMA fibers (20.2 MPa). However, when the prisms with Fe-SMA fibers are heated to 160 °C and 200 °C, they recover their pre-defined shape, which applies prestress to the surrounding concrete. This prestress increases the load-bearing capacity of the prism, leading to higher flexural strength in the Fe-SMA specimens (26.65 MPa and 24.39 MPa, respectively) compared to their steel–fiber counterparts (19.46 MPa and 16.67 MPa, respectively). Based on these findings, a numerical model was developed to simulate the behavior of concrete composites reinforced with randomly dispersed Fe-SMA fibers. An algorithm was created to define the random distribution of fibers, and a novel modeling approach accounted for the end-hooked geometry by assigning different contact properties to the modeled straight fiber ends and middle sections. A mesh sensitivity analysis was performed to determine the optimal mesh size, and the model was validated by comparing numerical results with experimental data. In summary, the key finding of this work is that thermally activated Fe-SMA fibers can effectively prestress concrete and enhance its flexural strength beyond that achievable with conventional steel fibers at ambient conditions.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"467 ","pages":"Article 140309"},"PeriodicalIF":7.4,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421610","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}
Variability in pore characteristics and fiber dispersion among Engineered Cementitious Composites (ECC) prepared with different mixers crucially determines their mechanical behavior, highlighting the importance of mixer selection in ECC processing. However, the research on the mesoscopic performance of mixer types is currently inadequate. To address this deficiency, this paper employed three prevalent ECC mixers—pan, handheld, and planetary—to analyze the macroscopic performance and microscopic features of ECC across all strength grades. Utilizing CT-scan-based 3D reconstruction technology, it investigated the interplay between porosity traits, fiber dispersion, and the mechanical properties of ECCs fabricated with these mixers at various strength levels. Findings demonstrate the planetary mixer's dominance in producing ECC with superior compressive, tensile, and flexural strengths due to its ability to ensure even fiber distribution and form a more spherical pore structure. The advantage of planetary mixers becomes more evident with increasing compressive strength grades, consistently maintaining a fiber volume fraction of 1.5–2.5 % at higher strengths. In comparison, while handheld mixers achieve moderate performance, they fall short of planetary mixers' efficiency in attaining homogenous pore structures and fiber distribution. Pan mixers exhibit declining fiber distribution and increased pore irregularity as strength enhances, resulting in the poorest mechanical performance. This study delineates the impact of mixers on ECC's properties and reinforces the critical role of mixer choice in achieving desired mechanical characteristics in advanced engineering applications.
{"title":"Mixer influence on pore characteristics and fiber dispersion in Engineered Cementitious Composites across various strength grades","authors":"Minjin Cai , Hehua Zhu , Timon Rabczuk , Xiaoying Zhuang","doi":"10.1016/j.conbuildmat.2025.140380","DOIUrl":"10.1016/j.conbuildmat.2025.140380","url":null,"abstract":"<div><div>Variability in pore characteristics and fiber dispersion among Engineered Cementitious Composites (ECC) prepared with different mixers crucially determines their mechanical behavior, highlighting the importance of mixer selection in ECC processing. However, the research on the mesoscopic performance of mixer types is currently inadequate. To address this deficiency, this paper employed three prevalent ECC mixers—pan, handheld, and planetary—to analyze the macroscopic performance and microscopic features of ECC across all strength grades. Utilizing CT-scan-based 3D reconstruction technology, it investigated the interplay between porosity traits, fiber dispersion, and the mechanical properties of ECCs fabricated with these mixers at various strength levels. Findings demonstrate the planetary mixer's dominance in producing ECC with superior compressive, tensile, and flexural strengths due to its ability to ensure even fiber distribution and form a more spherical pore structure. The advantage of planetary mixers becomes more evident with increasing compressive strength grades, consistently maintaining a fiber volume fraction of 1.5–2.5 % at higher strengths. In comparison, while handheld mixers achieve moderate performance, they fall short of planetary mixers' efficiency in attaining homogenous pore structures and fiber distribution. Pan mixers exhibit declining fiber distribution and increased pore irregularity as strength enhances, resulting in the poorest mechanical performance. This study delineates the impact of mixers on ECC's properties and reinforces the critical role of mixer choice in achieving desired mechanical characteristics in advanced engineering applications.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"467 ","pages":"Article 140380"},"PeriodicalIF":7.4,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421612","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 : 2025-02-15DOI: 10.1016/j.conbuildmat.2025.140409
Huai Liu , Shuai bai , Heqing Gou , Fangyu Chen , Xinchun Guan
The accumulation of coal gangue (CG) has led to severe environmental pollution. Using calcined coal gangue (CCG) as a supplementary cementitious material (SCM) is an effective strategy for recycling CG. However, the low reactivity and high energy consumption of CCG present significant challenges. This study introduces an improved calcination method by incorporating a small amount of calcium chloride (CaCl2) into CG before calcination, which significantly increases the efficiency of CG calcination. The product obtained from this improved method (CGC) greatly enhances the strength and fluidity of cement. The study examines the impact of CaCl2 on CG during calcination and its subsequent effects on the properties of cement. The results indicate that adding CaCl2 during calcination effectively facilitates the transformation of minerals such as kaolinite, clinochlore, and illite into reactive forms of silicon and aluminum. CG calcined at 650 ℃ (CG650) exhibits increased reactivity, significantly enhancing its performance as a SCM. CG calcined at 850 °C (CG850) demonstrates even better reactivity, producing more hydration products with a higher degree of polymerization. CG650C, obtained by adding CaCl2 to CG650, promotes the formation of Friedel's salt, further contributing to the strength of the cement paste. CGC calcined at 650 °C (CGC650) combines the higher reactivity similar to CG850 with the filling effect of Friedel's salt, achieving the highest strength. Furthermore, when used as a SCM, CGC650 exhibits the lowest indices for CO2 emissions and cost.
{"title":"Effect of calcium chloride-assisted calcined coal gangue as a supplementary cementitious material (SCM) on cement strength and microstructure","authors":"Huai Liu , Shuai bai , Heqing Gou , Fangyu Chen , Xinchun Guan","doi":"10.1016/j.conbuildmat.2025.140409","DOIUrl":"10.1016/j.conbuildmat.2025.140409","url":null,"abstract":"<div><div>The accumulation of coal gangue (CG) has led to severe environmental pollution. Using calcined coal gangue (CCG) as a supplementary cementitious material (SCM) is an effective strategy for recycling CG. However, the low reactivity and high energy consumption of CCG present significant challenges. This study introduces an improved calcination method by incorporating a small amount of calcium chloride (CaCl<sub>2</sub>) into CG before calcination, which significantly increases the efficiency of CG calcination. The product obtained from this improved method (CGC) greatly enhances the strength and fluidity of cement. The study examines the impact of CaCl<sub>2</sub> on CG during calcination and its subsequent effects on the properties of cement. The results indicate that adding CaCl<sub>2</sub> during calcination effectively facilitates the transformation of minerals such as kaolinite, clinochlore, and illite into reactive forms of silicon and aluminum. CG calcined at 650 ℃ (CG650) exhibits increased reactivity, significantly enhancing its performance as a SCM. CG calcined at 850 °C (CG850) demonstrates even better reactivity, producing more hydration products with a higher degree of polymerization. CG650C, obtained by adding CaCl<sub>2</sub> to CG650, promotes the formation of Friedel's salt, further contributing to the strength of the cement paste. CGC calcined at 650 °C (CGC650) combines the higher reactivity similar to CG850 with the filling effect of Friedel's salt, achieving the highest strength. Furthermore, when used as a SCM, CGC650 exhibits the lowest indices for CO<sub>2</sub> emissions and cost.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"467 ","pages":"Article 140409"},"PeriodicalIF":7.4,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421611","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 : 2025-02-15DOI: 10.1016/j.conbuildmat.2025.140422
Fan Li , Daming Luo , Ditao Niu
Concrete exhibits significant variability, making it challenging to accurately determine many parameters, especially in quantifying damage caused by freeze-thaw cycles. Consequently, current methods for assessing concrete damage in freeze-thaw environments are often subjective and insufficient. This study integrates artificial intelligence with durability diagnostics by employing deep learning image recognition algorithms and X-CT scanning technology to develop an intelligent segmentation model for micropores inside concrete. The analysis focused on the evolution of pore structure parameters inside concrete under freeze-thaw cycles. By introducing fractal theory, the study examines the correlation between the fractal box-counting of internal concrete pores and the macro index under freeze-thaw cycles. A method utilizing the fractal box-counting dimension of internal pores as a damage variable to evaluate concrete's freeze-thaw durability is proposed. Results indicate that the intelligent segmentation model established using the U-Net3 + deep learning algorithm effectively captures and quantifies the complex internal pore information in concrete. This provides a comprehensive and intuitive approach to exploring the evolution of internal pore structures in concrete under complex service environments. As freeze-thaw cycles increase, the fractal box-counting dimension of internal pores in concrete gradually increases, and the pore structure transition from ordered to disordered. The complexity of pore space distribution also increases. A strong linear correlation exists between the fractal box-counting dimension at the micro level and concrete's macro index at the macro level. The new concrete freeze-thaw degradation assessment method proposed in this study can be used to accurately evaluate the freeze-thaw damage status of concrete.
{"title":"Durability evaluation of concrete structure under freeze-thaw environment based on pore evolution derived from deep learning","authors":"Fan Li , Daming Luo , Ditao Niu","doi":"10.1016/j.conbuildmat.2025.140422","DOIUrl":"10.1016/j.conbuildmat.2025.140422","url":null,"abstract":"<div><div>Concrete exhibits significant variability, making it challenging to accurately determine many parameters, especially in quantifying damage caused by freeze-thaw cycles. Consequently, current methods for assessing concrete damage in freeze-thaw environments are often subjective and insufficient. This study integrates artificial intelligence with durability diagnostics by employing deep learning image recognition algorithms and X-CT scanning technology to develop an intelligent segmentation model for micropores inside concrete. The analysis focused on the evolution of pore structure parameters inside concrete under freeze-thaw cycles. By introducing fractal theory, the study examines the correlation between the fractal box-counting of internal concrete pores and the macro index under freeze-thaw cycles. A method utilizing the fractal box-counting dimension of internal pores as a damage variable to evaluate concrete's freeze-thaw durability is proposed. Results indicate that the intelligent segmentation model established using the U-Net3 + deep learning algorithm effectively captures and quantifies the complex internal pore information in concrete. This provides a comprehensive and intuitive approach to exploring the evolution of internal pore structures in concrete under complex service environments. As freeze-thaw cycles increase, the fractal box-counting dimension of internal pores in concrete gradually increases, and the pore structure transition from ordered to disordered. The complexity of pore space distribution also increases. A strong linear correlation exists between the fractal box-counting dimension at the micro level and concrete's macro index at the macro level. The new concrete freeze-thaw degradation assessment method proposed in this study can be used to accurately evaluate the freeze-thaw damage status of concrete.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"467 ","pages":"Article 140422"},"PeriodicalIF":7.4,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421616","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号