Pub Date : 2024-11-15DOI: 10.1016/j.conbuildmat.2024.139209
Jitong Ding , Jiwang Jiang , Guoyang Lu , Jingling Wang , Fujian Ni
Aging increases the stiffness and brittleness of asphalt mixtures, making it crucial to predict changes in mixture properties over time. This study aims to investigate oxidation reactions in the wearing course of asphalt pavement under oxygen diffusion. A multi-physics model, incorporating modules for thermal conductivity, oxygen diffusion, and oxidation reactions, was developed to analyze the formation of partial oxidation products in asphalt mortar. The model was optimized and validated using field data from ten road sections of Jiangsu highways. The impact of service time, location, and mixture type on aging was examined, allowing for network-level predictions of oxidation aging. Results indicate that as service time increases, the aging gradient between the surface and bottom of the wearing course becomes more pronounced. After 15 years, the surface carbonyl index increases to 330–350, while the bottom index reaches 150–180. This variation is influenced by climatic conditions and changes in mortar film thickness. These findings enhance the understanding of factors influencing field aging and improve predictions under varied conditions.
{"title":"Multi-physical modeling and automatic network-level prediction of the oxidation aging of in-situ asphalt pavements","authors":"Jitong Ding , Jiwang Jiang , Guoyang Lu , Jingling Wang , Fujian Ni","doi":"10.1016/j.conbuildmat.2024.139209","DOIUrl":"10.1016/j.conbuildmat.2024.139209","url":null,"abstract":"<div><div>Aging increases the stiffness and brittleness of asphalt mixtures, making it crucial to predict changes in mixture properties over time. This study aims to investigate oxidation reactions in the wearing course of asphalt pavement under oxygen diffusion. A multi-physics model, incorporating modules for thermal conductivity, oxygen diffusion, and oxidation reactions, was developed to analyze the formation of partial oxidation products in asphalt mortar. The model was optimized and validated using field data from ten road sections of Jiangsu highways. The impact of service time, location, and mixture type on aging was examined, allowing for network-level predictions of oxidation aging. Results indicate that as service time increases, the aging gradient between the surface and bottom of the wearing course becomes more pronounced. After 15 years, the surface carbonyl index increases to 330–350, while the bottom index reaches 150–180. This variation is influenced by climatic conditions and changes in mortar film thickness. These findings enhance the understanding of factors influencing field aging and improve predictions under varied conditions.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139209"},"PeriodicalIF":7.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.conbuildmat.2024.139011
Caterina Biscaro , Ariadna Martínez , Adrià Pérez , Giovanna Xotta , Carlos Maria López , Ignacio Carol
External Sulfate Attack (ESA) is a chemical degradation process that may affect concrete structures exposed to sulfate-rich environments. The ingress of sulfate ions causes chemical reactions leading to the formation of secondary ettringite, with significant volume expansion and subsequent characteristic cracking. The model proposed combines a diffusion-reaction model with a meso-mechanical model in which the larger aggregates are represented explicitly and pre-inserted fracture-based zero-thickness interface elements represent potential cracks. In the model, opening cracks also become preferential diffusion paths for sulfate penetration, which brings in chemical-mechanical coupling in a staggered scheme. By exploiting improved calculation capabilities, significant extensions of previous 2D results and new 3D calculations have been obtained. The new results demonstrate the model's effectiveness in realistically replicating “onion-peel” cracking and spalling patterns observed in experiments, as well as to sulfate ion penetration profiles.
{"title":"‘Onion-peel’ cracking and spalling in coupled meso-mechanical analysis of External Sulfate Attack in concrete using zero-thickness interface elements","authors":"Caterina Biscaro , Ariadna Martínez , Adrià Pérez , Giovanna Xotta , Carlos Maria López , Ignacio Carol","doi":"10.1016/j.conbuildmat.2024.139011","DOIUrl":"10.1016/j.conbuildmat.2024.139011","url":null,"abstract":"<div><div>External Sulfate Attack (ESA) is a chemical degradation process that may affect concrete structures exposed to sulfate-rich environments. The ingress of sulfate ions causes chemical reactions leading to the formation of secondary ettringite, with significant volume expansion and subsequent characteristic cracking. The model proposed combines a diffusion-reaction model with a meso-mechanical model in which the larger aggregates are represented explicitly and pre-inserted fracture-based zero-thickness interface elements represent potential cracks. In the model, opening cracks also become preferential diffusion paths for sulfate penetration, which brings in chemical-mechanical coupling in a staggered scheme. By exploiting improved calculation capabilities, significant extensions of previous 2D results and new 3D calculations have been obtained. The new results demonstrate the model's effectiveness in realistically replicating “onion-peel” cracking and spalling patterns observed in experiments, as well as to sulfate ion penetration profiles.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139011"},"PeriodicalIF":7.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142663828","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}
Enhancing the performance of fiber-reinforced concrete through the meticulous regulation of interfacial microstructure and interaction mode stands as a pivotal area of research. Notably, there are significant differences in the microstructure of several polycrystalline forms of calcium carbonate, which can profoundly influence the interaction behavior between them and the matrix. However, the tailored modulation of calcium carbonate polymorphism for the purpose of fiber surface modification remains unreported. In this paper, polycrystalline mineralization was induced by polydopamine on the surface of polyvinyl alcohol fiber by biomimetic method, and the fiber surface was modified by calcite and aragonite. The cubic calcite and acicular aragonite minerals notably roughened the fiber surface, enhancing interfacial properties between PVA fibers and cement matrix. The damaged form of the interface changed from adhesion failure to cohesive failure. Quantitative assessment of fiber-matrix interfacial interactions via single-fiber pullout tests revealed aragonite's unique morphology and exceptional mechanical attributes yielding higher frictional resistance against pullout loads. The good bonding between calcite and the cement matrix improves the strain-hardening behavior of fiber pullout and significantly enhances energy dissipation. In addition, enhanced interfacial properties bolster composites' mechanical strength. The acicular and cubic mineralized layers increased the flexural strength of the fiber cementitious materials by 35 % and 41 %, respectively. The energy absorbed in resisting the impact of a falling ball increased by 25 % and 36 %, respectively. Analysis reveals calcite promotes hydration more significantly at comparable particle sizes, bolstering interfacial bond strength with cement, and offering superior reinforcement over aragonite for fiber matrix bridging. This research provides a theoretical basis for promoting the application of polycrystalline CaCO3 and the sustainable development of high-performance fiber-reinforced concrete.
{"title":"Performance augmentation of fiber reinforced concrete through in situ mineralization of polycrystalline calcium carbonate on fiber surfaces","authors":"Kailu Han, Xiaoyue Jia, Tongran Li, Mingze Sun, Bing Yin, Dongshuai Hou","doi":"10.1016/j.conbuildmat.2024.139141","DOIUrl":"10.1016/j.conbuildmat.2024.139141","url":null,"abstract":"<div><div>Enhancing the performance of fiber-reinforced concrete through the meticulous regulation of interfacial microstructure and interaction mode stands as a pivotal area of research. Notably, there are significant differences in the microstructure of several polycrystalline forms of calcium carbonate, which can profoundly influence the interaction behavior between them and the matrix. However, the tailored modulation of calcium carbonate polymorphism for the purpose of fiber surface modification remains unreported. In this paper, polycrystalline mineralization was induced by polydopamine on the surface of polyvinyl alcohol fiber by biomimetic method, and the fiber surface was modified by calcite and aragonite. The cubic calcite and acicular aragonite minerals notably roughened the fiber surface, enhancing interfacial properties between PVA fibers and cement matrix. The damaged form of the interface changed from adhesion failure to cohesive failure. Quantitative assessment of fiber-matrix interfacial interactions via single-fiber pullout tests revealed aragonite's unique morphology and exceptional mechanical attributes yielding higher frictional resistance against pullout loads. The good bonding between calcite and the cement matrix improves the strain-hardening behavior of fiber pullout and significantly enhances energy dissipation. In addition, enhanced interfacial properties bolster composites' mechanical strength. The acicular and cubic mineralized layers increased the flexural strength of the fiber cementitious materials by 35 % and 41 %, respectively. The energy absorbed in resisting the impact of a falling ball increased by 25 % and 36 %, respectively. Analysis reveals calcite promotes hydration more significantly at comparable particle sizes, bolstering interfacial bond strength with cement, and offering superior reinforcement over aragonite for fiber matrix bridging. This research provides a theoretical basis for promoting the application of polycrystalline CaCO<sub>3</sub> and the sustainable development of high-performance fiber-reinforced concrete.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139141"},"PeriodicalIF":7.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.conbuildmat.2024.139185
Van-Huong Nguyen , Nordine Leklou , Pierre Mounanga
Internal sulfate attack induces the formation of delayed ettringite (DEF) in hardened cement-based materials. DEF is a complex phenomenon, detrimental to the durability of concrete and which develops in the long term, depending on the temperature history of the material at early age, its composition, its physicochemical and mechanical properties, and the environmental conditions. Today, the risk assessment and prediction of this pathology are still mainly based on laboratory tests which can extend over several months, or even several years. In this context, the objective of the present study is to develop two original experimental devices, making it possible to shorten the time needed to detect the risk of potential internal sulphate attack, using the application of an electric field on mortar and concrete specimens. The results obtained, coupled with microstructural observations carried out using scanning electronic microscopy, show that the two devices make it possible to both accelerate DEF, through electromigration, and measure simultaneously, continuously and automatically the longitudinal and lateral specimen deformations related to the formation of delayed ettringite. Using the devices developed, the time needed to observe the swelling threshold of 0.04 % is divided by a ratio of 2–2.5 and 1.7–1.9 between the mortar and concrete specimens subjected to electric field and the control mortar and concrete specimens, respectively.
{"title":"Development of accelerated test methods by electromigration to assess the risk of internal sulfate attack in heat-cured mortar and concrete","authors":"Van-Huong Nguyen , Nordine Leklou , Pierre Mounanga","doi":"10.1016/j.conbuildmat.2024.139185","DOIUrl":"10.1016/j.conbuildmat.2024.139185","url":null,"abstract":"<div><div>Internal sulfate attack induces the formation of delayed ettringite (DEF) in hardened cement-based materials. DEF is a complex phenomenon, detrimental to the durability of concrete and which develops in the long term, depending on the temperature history of the material at early age, its composition, its physicochemical and mechanical properties, and the environmental conditions. Today, the risk assessment and prediction of this pathology are still mainly based on laboratory tests which can extend over several months, or even several years. In this context, the objective of the present study is to develop two original experimental devices, making it possible to shorten the time needed to detect the risk of potential internal sulphate attack, using the application of an electric field on mortar and concrete specimens. The results obtained, coupled with microstructural observations carried out using scanning electronic microscopy, show that the two devices make it possible to both accelerate DEF, through electromigration, and measure simultaneously, continuously and automatically the longitudinal and lateral specimen deformations related to the formation of delayed ettringite. Using the devices developed, the time needed to observe the swelling threshold of 0.04 % is divided by a ratio of 2–2.5 and 1.7–1.9 between the mortar and concrete specimens subjected to electric field and the control mortar and concrete specimens, respectively.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139185"},"PeriodicalIF":7.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.conbuildmat.2024.139037
Tarikul Hasan , João R. Correia , Mário Garrido , Francisco Soares , Susana Cabral-Fonseca , Marco Jorge , José Sena-Cruz
This paper presents an experimental study about the effects of freeze-thaw cycles (FTC) on the mechanical and thermomechanical properties of glass-fibre reinforced polymer composite laminates produced by vacuum infusion using two different polymer resins: unsaturated polyester (UP) and vinyl ester (VE). Following preconditioning in distilled water for 30 days at 20 °C, the composites were subjected to 100, 200 and 300 FTC, with temperature ranging from −20 °C to 23 °C. After the preconditioning and each ageing period, the mechanical properties of the composites were assessed through tension, compression, flexure, in-plane shear and interlaminar shear tests, as well as DMA, which were complemented by FTIR analysis and SEM observations. The results obtained indicate a slight-to-moderate reduction of glass transition temperature and mechanical properties, especially of flexural strength (up to 29 %) and compressive strength (up to 16 %). These reductions were partially reversible upon drying, highlighting relevant moisture-induced plasticization effects. On the other hand, no clear evidence of significant hydrolysis or fibre-matrix debonding was identified from respectively FTIR and SEM. Overall, the VE composite exhibited better overall performance than the UP composite. It was not possible to identify clear differences in the freeze-thaw durability performance of the vacuum infused composites tested in this study compared to pultruded composites reported in the literature.
本文介绍了一项关于冻融循环（FTC）对玻璃纤维增强聚合物复合材料层压板机械性能和热机械性能影响的实验研究，该层压板是使用两种不同的聚合物树脂（不饱和聚酯（UP）和乙烯基酯（VE））通过真空灌注生产的。复合材料在 20 °C 的蒸馏水中预处理 30 天后，分别进行了 100、200 和 300 次 FTC，温度范围为 -20 °C 至 23 °C。在预处理和每个老化期结束后，通过拉伸、压缩、弯曲、平面内剪切和层间剪切试验以及 DMA 评估了复合材料的机械性能，并进行了傅立叶变换红外分析和扫描电镜观察。研究结果表明，玻璃化转变温度和机械性能，尤其是抗弯强度（最高达 29%）和抗压强度（最高达 16%）略有下降。这些降低在干燥后是部分可逆的，凸显了相关的湿气诱导塑化效应。另一方面，傅立叶变换红外光谱（FTIR）和扫描电子显微镜（SEM）均未发现明显的水解或纤维基质脱粘迹象。总体而言，VE 复合材料的整体性能优于 UP 复合材料。与文献报道的拉挤复合材料相比，本研究中测试的真空灌注复合材料在冻融耐久性能方面没有明显差异。
{"title":"Freeze-thaw durability of vacuum infused glass fibre composites with unsaturated polyester and vinyl ester matrices","authors":"Tarikul Hasan , João R. Correia , Mário Garrido , Francisco Soares , Susana Cabral-Fonseca , Marco Jorge , José Sena-Cruz","doi":"10.1016/j.conbuildmat.2024.139037","DOIUrl":"10.1016/j.conbuildmat.2024.139037","url":null,"abstract":"<div><div>This paper presents an experimental study about the effects of freeze-thaw cycles (FTC) on the mechanical and thermomechanical properties of glass-fibre reinforced polymer composite laminates produced by vacuum infusion using two different polymer resins: unsaturated polyester (UP) and vinyl ester (VE). Following preconditioning in distilled water for 30 days at 20 °C, the composites were subjected to 100, 200 and 300 FTC, with temperature ranging from −20 °C to 23 °C. After the preconditioning and each ageing period, the mechanical properties of the composites were assessed through tension, compression, flexure, in-plane shear and interlaminar shear tests, as well as DMA, which were complemented by FTIR analysis and SEM observations. The results obtained indicate a slight-to-moderate reduction of glass transition temperature and mechanical properties, especially of flexural strength (up to 29 %) and compressive strength (up to 16 %). These reductions were partially reversible upon drying, highlighting relevant moisture-induced plasticization effects. On the other hand, no clear evidence of significant hydrolysis or fibre-matrix debonding was identified from respectively FTIR and SEM. Overall, the VE composite exhibited better overall performance than the UP composite. It was not possible to identify clear differences in the freeze-thaw durability performance of the vacuum infused composites tested in this study compared to pultruded composites reported in the literature.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139037"},"PeriodicalIF":7.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.conbuildmat.2024.139095
Yao Xiao , Chaofan Wang , Bing Chen
This study investigated the impact of fineness of magnesium oxide (MgO) on the performance of magnesium phosphate cement (MPC) and analysis from the fresh and hardened properties of MPC. The fresh properties were determined by the setting time, fluidity, and early hydration heat evolution, the hardened properties were characterized by compressive strength and water resistance. The microstructure and hydration products were examined by XRD, TG-DTG and SEM. The results showed that a decrease in particle size of MgO resulted in reduction of the fluidity of MPC from 175 mm to 108 mm and shortening of setting time to 340 s and a continuously decrease in the exothermic reaction intensity. Finer MgO particles exhibit great influence on the later compressive strength of MPC paste and enhance the water resistance. The specimen with the smallest fineness of MgO yielded the highest compressive strength of 51.55 MPa at 28 days, which was pronouncedly improved by 35.41 % comparing to the controlled group. Besides, MgO with the particle size range of 20–60 μm is favorable to the late-stage compressive strength of MPC paste. Moreover, obtained results from the micro analysis showed that small size MgO promotes the formation of crystalline struvite and amorphous hydration products. The microstructure became more compact with less microcracks and defects as the fineness of MgO decreased.
{"title":"Understanding the role of MgO fineness on the performance of magnesium phosphate cement through multi-scale study","authors":"Yao Xiao , Chaofan Wang , Bing Chen","doi":"10.1016/j.conbuildmat.2024.139095","DOIUrl":"10.1016/j.conbuildmat.2024.139095","url":null,"abstract":"<div><div>This study investigated the impact of fineness of magnesium oxide (MgO) on the performance of magnesium phosphate cement (MPC) and analysis from the fresh and hardened properties of MPC. The fresh properties were determined by the setting time, fluidity, and early hydration heat evolution, the hardened properties were characterized by compressive strength and water resistance. The microstructure and hydration products were examined by XRD, TG-DTG and SEM. The results showed that a decrease in particle size of MgO resulted in reduction of the fluidity of MPC from 175 mm to 108 mm and shortening of setting time to 340 s and a continuously decrease in the exothermic reaction intensity. Finer MgO particles exhibit great influence on the later compressive strength of MPC paste and enhance the water resistance. The specimen with the smallest fineness of MgO yielded the highest compressive strength of 51.55 MPa at 28 days, which was pronouncedly improved by 35.41 % comparing to the controlled group. Besides, MgO with the particle size range of 20–60 μm is favorable to the late-stage compressive strength of MPC paste. Moreover, obtained results from the micro analysis showed that small size MgO promotes the formation of crystalline struvite and amorphous hydration products. The microstructure became more compact with less microcracks and defects as the fineness of MgO decreased.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139095"},"PeriodicalIF":7.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.conbuildmat.2024.139181
Xinliang Sun , Zhiqiang Dong , Cui Zou , Hong Zhu , Yu Sun , Yijie Pan
Hinge joints provide key lateral connections within hollow-core slab (HCS) bridges, providing load transfer between adjacent beams. However, hinge joints are prone to cracking, which is a common problem in HCS bridges. Therefore, the present study proposes a novel technique for transverse strengthening of hinge joints by utilizing locally near-surface mounted (NSM) Fe-SMA bars, based on the self-prestressing mechanism of iron-based shape memory alloys (Fe-SMAs). To verify the feasibility of the strengthening technique, 13 slab beam-hinge joint specimens are prepared and loaded under a flexural-shear load in combination with digital image correlation (DIC) tests. The test series encompasses two quantities of Fe-SMA bars (one and two), two activation lengths (100 mm and 200 mm), and three activation temperatures (non-activated, 200 ℃, and 400 ℃). The generated self-prestress level for the strengthening technique is investigated based on experimental data. The results indicate that the strengthening technique can effectively enhance the lateral connection of adjacent HCS beams and the mechanical behavior of hinge joints. Increasing the quantity of Fe-SMA bars and the activation temperature can significantly increase the cracking load, crack penetration load, and ultimate load of hinge joints. Activation lengths of 100 mm and 200 mm have a limited effect on strengthening. At 200 ℃ and 400 ℃ activation temperatures, the effective prestresses based on analysis are 277 ± 19 MPa and 411 ± 21 MPa, respectively.
{"title":"Hinge joint performance in hollow-core slab bridges transversely strengthened with local near-surface mounted iron-based shape memory alloy (Fe-SMA) bars","authors":"Xinliang Sun , Zhiqiang Dong , Cui Zou , Hong Zhu , Yu Sun , Yijie Pan","doi":"10.1016/j.conbuildmat.2024.139181","DOIUrl":"10.1016/j.conbuildmat.2024.139181","url":null,"abstract":"<div><div>Hinge joints provide key lateral connections within hollow-core slab (HCS) bridges, providing load transfer between adjacent beams. However, hinge joints are prone to cracking, which is a common problem in HCS bridges. Therefore, the present study proposes a novel technique for transverse strengthening of hinge joints by utilizing locally near-surface mounted (NSM) Fe-SMA bars, based on the self-prestressing mechanism of iron-based shape memory alloys (Fe-SMAs). To verify the feasibility of the strengthening technique, 13 slab beam-hinge joint specimens are prepared and loaded under a flexural-shear load in combination with digital image correlation (DIC) tests. The test series encompasses two quantities of Fe-SMA bars (one and two), two activation lengths (100 mm and 200 mm), and three activation temperatures (non-activated, 200 ℃, and 400 ℃). The generated self-prestress level for the strengthening technique is investigated based on experimental data. The results indicate that the strengthening technique can effectively enhance the lateral connection of adjacent HCS beams and the mechanical behavior of hinge joints. Increasing the quantity of Fe-SMA bars and the activation temperature can significantly increase the cracking load, crack penetration load, and ultimate load of hinge joints. Activation lengths of 100 mm and 200 mm have a limited effect on strengthening. At 200 ℃ and 400 ℃ activation temperatures, the effective prestresses based on analysis are 277 ± 19 MPa and 411 ± 21 MPa, respectively.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139181"},"PeriodicalIF":7.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.conbuildmat.2024.139189
Lei Zhang , Lijie Guo , Shaoqing Liu , Xiaoming Wei , Yue Zhao , Mengyuan Li
With the increasingly prominent problems of cement cemented fine tailings backfill (CFTB), the demand for higher performance, economical, and low-carbon new binder is constantly increasing. This paper comparatively studies the workability and mechanical properties of ordinary Portland cement (PC) and two types of new binders (SC and SGL) CFTB. Additionally, the microstructural and gel products of CFTB are analyzed by hydration heat, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), thermos-gravimetry (TG), and mercury intrusion porosimetry (MIP). The results reveal that compared to CFTB-PC, CFTB-SC and CFTB-SGL exhibit reduced fluidity and bleeding rates, alongside increased yield stress and plastic viscosity. CFTB-PC sets and hardens rapidly, but its uniaxial compressive strength (UCS) increases slowly. CFTB-SC and CFTB-SLG set and harden more slowly than CFTB-PC, but their UCS increases more rapidly. The 3 d UCS of CFTB-SC and CFTB-SGL surpasses that of CFTB-PC, and the 7 d-360 d UCS reaches 1.66–2.66 times that of CFTB-PC. The 3 d-14 d UCS of CFTB-SC is lower than that of CFTB-SGL, but the 28 d-360 d UCS is 13.78 % higher than that of CFTB-SGL on average. The hydration rate and total hydration heat release follow the order PC > SC > SGL. The hydration products of CFTB-PC mainly consist of fibrous C-S-H gel with unidirectional distribution, while those of CFTB-SC and CFTB-SGL are characterized by foil-like C-S-H gel with three-dimensional non-directional distribution and needle bar-like ettringite with skeleton support function, facilitating closely embedded with fine tailings. The pores in CFTB-PC are predominantly large pores (d ≥ 1000 nm), whereas those in CFTB-SC and CFTB-SGL are mainly transition pores (10 nm ≤ d < 100 nm) and capillary pores (100 nm ≤ d < 1000 nm). The research results provide theoretical guidance for the development of new filling binder.
{"title":"A comparative study on the workability, mechanical properties and microstructure of cemented fine tailings backfill with different binder","authors":"Lei Zhang , Lijie Guo , Shaoqing Liu , Xiaoming Wei , Yue Zhao , Mengyuan Li","doi":"10.1016/j.conbuildmat.2024.139189","DOIUrl":"10.1016/j.conbuildmat.2024.139189","url":null,"abstract":"<div><div>With the increasingly prominent problems of cement cemented fine tailings backfill (CFTB), the demand for higher performance, economical, and low-carbon new binder is constantly increasing. This paper comparatively studies the workability and mechanical properties of ordinary Portland cement (PC) and two types of new binders (SC and SGL) CFTB. Additionally, the microstructural and gel products of CFTB are analyzed by hydration heat, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), thermos-gravimetry (TG), and mercury intrusion porosimetry (MIP). The results reveal that compared to CFTB-PC, CFTB-SC and CFTB-SGL exhibit reduced fluidity and bleeding rates, alongside increased yield stress and plastic viscosity. CFTB-PC sets and hardens rapidly, but its uniaxial compressive strength (UCS) increases slowly. CFTB-SC and CFTB-SLG set and harden more slowly than CFTB-PC, but their UCS increases more rapidly. The 3 d UCS of CFTB-SC and CFTB-SGL surpasses that of CFTB-PC, and the 7 d-360 d UCS reaches 1.66–2.66 times that of CFTB-PC. The 3 d-14 d UCS of CFTB-SC is lower than that of CFTB-SGL, but the 28 d-360 d UCS is 13.78 % higher than that of CFTB-SGL on average. The hydration rate and total hydration heat release follow the order PC > SC > SGL. The hydration products of CFTB-PC mainly consist of fibrous C-S-H gel with unidirectional distribution, while those of CFTB-SC and CFTB-SGL are characterized by foil-like C-S-H gel with three-dimensional non-directional distribution and needle bar-like ettringite with skeleton support function, facilitating closely embedded with fine tailings. The pores in CFTB-PC are predominantly large pores (d ≥ 1000 nm), whereas those in CFTB-SC and CFTB-SGL are mainly transition pores (10 nm ≤ d < 100 nm) and capillary pores (100 nm ≤ d < 1000 nm). The research results provide theoretical guidance for the development of new filling binder.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139189"},"PeriodicalIF":7.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.conbuildmat.2024.139229
Yinqiao Xu , Quantao Liu , Huan Wang , Shaopeng Wu
The aging of asphalt mixtures shortens the lifespan of asphalt pavements. Incorporating antioxidant intercalated layered double hydroxides (OLDHs) into asphalt is a viable approach to enhance the resistance of the asphalt binder to aging. However, OLDHs hasn’t been optimized and its effectiveness in asphalt mixture is not clear. This study is to synthetize different OLDHs and examine their enhancements on the anti-aging performance of SBS modified asphalt mixture (SMAM). For this purpose, ion-exchange method was employed to intercalate antioxidant 1222, antioxidant 1010, and 3-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid into the interlayers of Mg/Al-LDHs to prepare different OLDHs (designated as 1010-LDHs, 1222-LDHs, and 3B-LDHs, respectively). The synthesized OLDHs were characterized by crystal phase, chemical structure, micro-morphology, UV–visible spectroscopy and free radical scavenging tests. The three prepared OLDHs were then added to the SBS modified asphalt (SBSMA) and mixtures were prepared with both OLDHs-containing and non-OLDHs-containing asphalts. Aging tests were conducted, and the changes in pavement performance of different mixtures before and after aging were compared to assess the effects of OLDHs on the anti-aging properties of SMAM. Finally, asphalt binders were extracted from different aged mixtures and subjected to relevant tests. The results indicate that all three antioxidants were successfully intercalated into the LDHs while maintaining the layered structure. Additionally, the incorporation of the three OLDHs improved the ultraviolet and thermal-oxidative aging (TO aging) resistances of the SMAM. Among the three, 3B-LDHs demonstrated the best anti-aging enhancement at the same dosage. These findings offer a reference for studying and applying OLDHs to enhance the anti-aging properties of SMAM.
{"title":"Synthesis of different antioxidant intercalated layered double hydroxides and their enhancement on aging resistance of SBS modified asphalt mixture","authors":"Yinqiao Xu , Quantao Liu , Huan Wang , Shaopeng Wu","doi":"10.1016/j.conbuildmat.2024.139229","DOIUrl":"10.1016/j.conbuildmat.2024.139229","url":null,"abstract":"<div><div>The aging of asphalt mixtures shortens the lifespan of asphalt pavements. Incorporating antioxidant intercalated layered double hydroxides (OLDHs) into asphalt is a viable approach to enhance the resistance of the asphalt binder to aging. However, OLDHs hasn’t been optimized and its effectiveness in asphalt mixture is not clear. This study is to synthetize different OLDHs and examine their enhancements on the anti-aging performance of SBS modified asphalt mixture (SMAM). For this purpose, ion-exchange method was employed to intercalate antioxidant 1222, antioxidant 1010, and 3-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid into the interlayers of Mg/Al-LDHs to prepare different OLDHs (designated as 1010-LDHs, 1222-LDHs, and 3B-LDHs, respectively). The synthesized OLDHs were characterized by crystal phase, chemical structure, micro-morphology, UV–visible spectroscopy and free radical scavenging tests. The three prepared OLDHs were then added to the SBS modified asphalt (SBSMA) and mixtures were prepared with both OLDHs-containing and non-OLDHs-containing asphalts. Aging tests were conducted, and the changes in pavement performance of different mixtures before and after aging were compared to assess the effects of OLDHs on the anti-aging properties of SMAM. Finally, asphalt binders were extracted from different aged mixtures and subjected to relevant tests. The results indicate that all three antioxidants were successfully intercalated into the LDHs while maintaining the layered structure. Additionally, the incorporation of the three OLDHs improved the ultraviolet and thermal-oxidative aging (TO aging) resistances of the SMAM. Among the three, 3B-LDHs demonstrated the best anti-aging enhancement at the same dosage. These findings offer a reference for studying and applying OLDHs to enhance the anti-aging properties of SMAM.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139229"},"PeriodicalIF":7.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.conbuildmat.2024.139201
Yuanlang Zhao , Xiao Zhang , Fan Li , Hengji Zhang , Bo Li , Xingke Chang
Crumb rubber modified asphalt (CRMA) has garnered attention for its superior low-temperature crack resistance, yet its high viscosity hinders practical application. Naphthenic oil (NO), employed as a viscosity-reducing agent, effectively lowers CRMA viscosity, but its influence on CRMA's fatigue and rheological properties remains unclear. This study prepares viscosity-reduced CRMA via both non-swelling and pre-swelling processes, assessing the impact of NO and the viscosity reduction processes on CRMA's fatigue life at −12°C, 25°C, and 65°C. Fourier Transform Infrared Spectroscopy (FTIR) and Molecular Dynamics (MD) simulations analyze the mechanism of NO action from a molecular energy perspective. Results show that NO and the reduction process affect the loss of polar functional groups and molecular energy in CRMA, thereby altering its fatigue life. Specifically, at −12°C, NO enhances CRMA's fatigue life, while the pre-swelling process decreases it. At 25°C, both NO and pre-swelling improve CRMA's fatigue life, but at 65°C, they diminish it. Furthermore, the coverage of CRMA surfaces by NO molecules and the poor gradation of rubber particles reduce CRMA's high-temperature deformation resistance but enhance low-temperature crack resistance. The pre-swelling process, compared to the non-swelling one, strengthens CRMA's rheological properties at both high and low temperatures.
{"title":"Effect of naphthenic oil and viscosity reduction process on fatigue life and rheological properties of crumb rubber modified asphalt","authors":"Yuanlang Zhao , Xiao Zhang , Fan Li , Hengji Zhang , Bo Li , Xingke Chang","doi":"10.1016/j.conbuildmat.2024.139201","DOIUrl":"10.1016/j.conbuildmat.2024.139201","url":null,"abstract":"<div><div>Crumb rubber modified asphalt (CRMA) has garnered attention for its superior low-temperature crack resistance, yet its high viscosity hinders practical application. Naphthenic oil (NO), employed as a viscosity-reducing agent, effectively lowers CRMA viscosity, but its influence on CRMA's fatigue and rheological properties remains unclear. This study prepares viscosity-reduced CRMA via both non-swelling and pre-swelling processes, assessing the impact of NO and the viscosity reduction processes on CRMA's fatigue life at −12°C, 25°C, and 65°C. Fourier Transform Infrared Spectroscopy (FTIR) and Molecular Dynamics (MD) simulations analyze the mechanism of NO action from a molecular energy perspective. Results show that NO and the reduction process affect the loss of polar functional groups and molecular energy in CRMA, thereby altering its fatigue life. Specifically, at −12°C, NO enhances CRMA's fatigue life, while the pre-swelling process decreases it. At 25°C, both NO and pre-swelling improve CRMA's fatigue life, but at 65°C, they diminish it. Furthermore, the coverage of CRMA surfaces by NO molecules and the poor gradation of rubber particles reduce CRMA's high-temperature deformation resistance but enhance low-temperature crack resistance. The pre-swelling process, compared to the non-swelling one, strengthens CRMA's rheological properties at both high and low temperatures.</div></div>","PeriodicalId":288,"journal":{"name":"Construction and Building Materials","volume":"455 ","pages":"Article 139201"},"PeriodicalIF":7.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664190","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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