Case Studies in Construction Materials最新文献

{"title":"Performance of cementitious high-pressure mixtures with wheat and corn straw fiber and straw ashes","authors":"Tchehoungbo Olivier Noukpo Houankpo,&nbsp;Zeyu Ma,&nbsp;Zhuan Zhao,&nbsp;Goubing Tian","doi":"10.1016/j.cscm.2024.e04175","DOIUrl":"10.1016/j.cscm.2024.e04175","url":null,"abstract":"<div><div>This study aimed to introduce a novel technique for producing straw fiber cement-based composites from wheat and corn straws. The research analyses the engineering characteristics, including compressive and flexural strengths, water absorption capacity, dry density, porosity, and thermal properties of the wheat and corn straw fiber cementitious composite (WCSFCC) mixtures. The hydration performance and compactness of WCSFCC mixes were described using XRD, SEM, and EDS analyses. The results show that the dosage of NaOH solution is the optimal approach for enhancing the surface of straw fibers and facilitating their effective integration with the cement matrix. The straw powder incineration method leads the straw ash particles to have a specific surface area 9.6 times higher than straw powder. The findings indicated that WCSFCC mixes with untreated straw powder had an optimal compressive strength ranging from 2.85 MPa to 3.79 MPa and corresponding thermal conductivity between 0.147 and 0.162 W/(m·K). Adopting the straw ash increased the compressive strength considerably. The analysis of WCSFCC mechanical properties and thermal conductivity with physical properties reveals a strong correlation between the mechanical properties and dry density, as well as thermal conductivity and dry density. However, the increasing porosity and water absorption capacity have compromised the mechanical properties and thermal conductivity of WCSFCC. The findings of this research may enhance the overall use of wheat and corn straw fibers. The manufacturing process of WCSFCC is simple, conducive to widespread use, and ecologically friendly.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"22 ","pages":"Article e04175"},"PeriodicalIF":6.5,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extended applications of molecular dynamics methods in multiscale studies of concrete composites: A review","authors":"Jie Cao ,&nbsp;Chao Wang ,&nbsp;Jaime Gonzalez-Libreros ,&nbsp;Tongfang Wang ,&nbsp;Yongming Tu ,&nbsp;Lennart Elfgren ,&nbsp;Gabriel Sas","doi":"10.1016/j.cscm.2024.e04153","DOIUrl":"10.1016/j.cscm.2024.e04153","url":null,"abstract":"<div><div>This paper investigates the current landscape of multiscale studies in concrete composites incorporating molecular dynamics (MD) methods. Through a thorough literature analysis, it was determined that finite element, discrete element, homogenization, microphysical characterization, and machine learning methods are better suited for integration with MD in multiscale studies of concrete composites. The paper delves into MD's application characteristics and the selection of force fields in multiscale studies and provides a summary of the combined applications between MD and various methods. Challenges identified include the optimization of MD simulations and the appropriate selection of combined methods. The conclusions underscore the growing recognition of MD's significance, advocating for rational multi-method integration in multiscale approaches to effectively advance research on concrete composites.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"22 ","pages":"Article e04153"},"PeriodicalIF":6.5,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143146188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the mechanical properties and mesoscopic damage mechanism of recycled aggregate concrete under different dynamic strain rates after freeze-thaw cycles","authors":"Chenyang Yuan ,&nbsp;Siying Qu ,&nbsp;Weifeng Bai ,&nbsp;Junfeng Guan ,&nbsp;Yunfei Xie","doi":"10.1016/j.cscm.2024.e04182","DOIUrl":"10.1016/j.cscm.2024.e04182","url":null,"abstract":"<div><div>In order to study the comprehensive influence of freeze-thaw cycles and dynamic strain rates on the mechanical properties of recycled aggregate concrete (RAC), uniaxial compression tests on RAC were carried out. The complete stress-strain curves under different numbers of freeze-thaw cycles (<em>N</em> = 0, 50, 100) and different strain rates (<span><math><mover><mi>ε</mi><mo>̇</mo></mover></math></span> = 10⁻⁵/s, 10⁻⁴/s, 10⁻³/s, 10⁻²/s) were obtained. Methods such as scanning electron microscopy (SEM) and acoustic emission (AE) were adopted to analyze the microstructure of the specimens and the development process of microcracks. The results showed that the specimens had poor frost resistance and significant strain rate sensitivity after undergoing freeze-thaw cycles, the strength and elastic modulus of the specimens decreased with the increase of the number of freeze-thaw cycles (<em>N</em>), and the strength and elastic modulus increased with the increase of the strain rate (<span><math><mover><mi>ε</mi><mo>̇</mo></mover></math></span>) under the same <em>N</em>. Combined with the statistical damage constitutive model, through the analysis of five parameters (<em>E</em>₀, <span><math><msub><mrow><mi>ε</mi></mrow><mrow><mi>a</mi></mrow></msub></math></span>, <span><math><msub><mrow><mi>ε</mi></mrow><mrow><mi>h</mi></mrow></msub></math></span>, <span><math><msub><mrow><mi>ε</mi></mrow><mrow><mi>b</mi></mrow></msub></math></span>, and <em>H</em>), the influence laws of freeze-thaw cycles and strain rates on the meso-damage evolution mechanism of RAC were revealed.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"22 ","pages":"Article e04182"},"PeriodicalIF":6.5,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143146189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of 3D satisfaction surface for concrete durability design under chloride attack considering climate change","authors":"Yeongmo Yeon,&nbsp;Jang-Ho Jay Kim","doi":"10.1016/j.cscm.2024.e04181","DOIUrl":"10.1016/j.cscm.2024.e04181","url":null,"abstract":"<div><div>Climate change significantly impacts the durability of concrete structures through variations in temperature and humidity, accelerating chloride ion penetration a primary cause of steel reinforcement corrosion. Rising sea levels, resulting from melting glaciers, further expose coastal infrastructures to these risks. Traditional design methods, which focus mainly on material properties like the water-cement ratio, are inadequate as they do not fully account for the complex and long-term environmental effects on concrete. This study introduces a 3D Performance-Based Evaluation (PBE) method that incorporates the effects of different curing conditions, including temperatures (8°C, 12°C, 20°C, 35°C, and 45°C) and relative humidity levels (40 %, 65 %, and 95 %), to evaluate and enhance concrete durability under chloride exposure. Experimental results indicate that higher curing temperatures increase chloride penetration, whereas higher humidity improves resistance. The service life of the target structure against chloride attack was evaluated using the proposed 3D PBE. The result show that the durability life of the structure decreased as the relative humidity decreased and the temperature increased during curing. In particular, this study predicted that the service life of the structure would decrease by 49 years to 68 years when the distance from the coastline decreased from 250 m to 100 m. The developed 3D PBE framework integrates these findings with probabilistic modeling, providing a comprehensive and adaptable approach to predict the service life of concrete structures affected by climate changes. Detailed information is provided in the main text.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"22 ","pages":"Article e04181"},"PeriodicalIF":6.5,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143146399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-term volume stability of steel slag sand mortar and concrete","authors":"Zhenhao Zhou ,&nbsp;Qiang Jin ,&nbsp;Di Hu ,&nbsp;Lin Zhu ,&nbsp;Zihua Li ,&nbsp;Wanzhong Su","doi":"10.1016/j.cscm.2024.e04179","DOIUrl":"10.1016/j.cscm.2024.e04179","url":null,"abstract":"<div><div>The stability of steel slag sand as an aggregate in mortar and concrete is currently a focal point of concern. The evaluation of steel slag stability typically employs short-term rapid methods, and research on the long-term stability of steel slag sand under natural curing conditions is relatively scarce. In this study, the rapid mortar bar method and alkaline-aggregate reaction method were used to compare the volumetric and apparent morphological changes in steel slag mortar and concrete under different curing conditions, with a focus on the effects of the steel slag sand aging time, substitution rate, particle size and curing conditions on the stability of steel slag sand. A combination of scanning electron microscopy and energy-dispersive X-ray spectroscopy was used to comprehensively investigate the mechanism of the deterioration of the stability of steel slag sand. The results show that the rapid mortar bar method exacerbates the degree of hazard of steel slag sand, whereas the long-term alkali-aggregate reaction test provides a more realistic assessment of the stability of steel slag sand. The results from the long-term alkali-aggregate reaction tests conducted over 0−156 weeks indicated that the replacement ratio of steel slag sand has a minimal impact on the volume of mortar and concrete. The degree of pinpoint surface damage to the samples is significantly correlated with the uneven distribution of free calcium oxide (f-CaO) within the steel slag sand, and the influence of f-CaO on surface damage showed a stochastic nature. When the particle size of steel slag is larger than 1.18 mm, the mortar sample is prone to point damage and fracture. The concrete samples made with single-particle-size steel slag sand simultaneously exhibit significant dry shrinkage and suppression of the hazards caused by the slow hydration of f-CaO. Overall, this paper evaluates the damage forms and degree of damage to the steel slag sand in mortar and concrete and provides a scientific basis for assessing steel slag sand stability.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"22 ","pages":"Article e04179"},"PeriodicalIF":6.5,"publicationDate":"2024-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143146226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of expansive agent on temperature and deformation of concrete under simulated actual construction condition","authors":"Ming Li ,&nbsp;Ang Su ,&nbsp;Hua Li ,&nbsp;Yujiang Wang ,&nbsp;Qian Tian","doi":"10.1016/j.cscm.2024.e04178","DOIUrl":"10.1016/j.cscm.2024.e04178","url":null,"abstract":"<div><div>Prolonging the setting time of concrete is a common requirement for the construction of massive structural engineering, and the molding temperature of concrete changes greatly with the construction season temperature. These actual construction conditions may bring challenges to the use of expansive agent (EA) to inhibit concrete cracking. This paper aims to investigate the effect of calcium oxide EA (CEA), magnesium oxide EA (MEA), and calcium magnesium composite EA (CMA) on the temperature and deformation of concrete under simulated actual construction condition by concrete member test, and discusses the hydration heat, autogenous shrinkage deformation and mechanical properties of cement-based materials containing EA under standard laboratory condition. Results show that CEA, MEA, and CMA increase the temperature rise of concrete members by 3 °C to 7.8 °C, which is not completely consistent with the hydration heat results under standard condition. For the concrete containing EA under the entity variable temperature, the extension of setting time and the increase of molding temperature reduce the shrinkage compensation ability of EA, the average expansion deformation rate of concrete in the temperature rise stage is reduced, and the average shrinkage deformation rate of concrete in the temperature drop stage is increased. Temperature rising inhibitor (TRI) is recommended to be used together with EA, which can eliminate the adverse effect of EA on the increase of temperature rise, greatly improve the shrinkage compensation ability of EA, and hardly reduce the later strength of concrete.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"22 ","pages":"Article e04178"},"PeriodicalIF":6.5,"publicationDate":"2024-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143146210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Embedded aluminum sections and prestressed high-performance concretes for improving shear performance of RC beams","authors":"Galal Elsamak ,&nbsp;Mohamed Ghalla ,&nbsp;Jong Wan Hu ,&nbsp;Abdullah Albogami ,&nbsp;Mohamed Emara ,&nbsp;Shiren Osman Ahmed","doi":"10.1016/j.cscm.2024.e04168","DOIUrl":"10.1016/j.cscm.2024.e04168","url":null,"abstract":"<div><div>The paper presents a novel sustainable technique for shear strengthening of reinforced concrete (RC) beams utilizing embedded aluminum boxes and prestressed high-performance concretes (HPCs). It addresses the challenges faced by existing RC structures, such as environmental threats, increased loading, and aging, which often lead to shear reinforcement deficiencies. Through an experimental program, the paper evaluates the impact of several parameters on the shear performance of beams, including the type of concrete filling the aluminum boxes, the type and diameter of reinforcement, and the level of prestressing force. The findings demonstrate the potential of this innovative technique to enhance the shear behavior of damaged RC beams, contributing to more sustainable construction practices. Results revealed that increasing the bar diameter provided marginal additional benefits. Moreover, the use of glass fiber reinforced polymer (GFRP) bars offered superior strengthening compared to steel bars. Additionally, beams strengthened with ultra-high-performance concrete (UHPC)-filled aluminum boxes and embedded steel/GFRP bars, demonstrated improved performance compared to strain-hardening cementitious composites (SHCC)-filled aluminum boxes. Applying a prestressing force significantly enhanced the behavior of strengthened beams, the ultimate capacity of one of them reaching that of the control beam. The level of enhancement directly correlated with the applied prestressing force. This research successfully validated a new finite element model (FEM) for analyzing concrete beams strengthened with aluminum boxes. The model accurately predicted shear strength of these beams. Additionally, a proposed formula for calculating shear capacity closely matched experimental results, showing a maximum discrepancy of only 2.5 %.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"22 ","pages":"Article e04168"},"PeriodicalIF":6.5,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143146181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strengthening of unreinforced masonry buildings with ferrocement composite overlay: Material characterization and numerical study","authors":"Anubhab Mukherjee,&nbsp;Hemant B. Kaushik","doi":"10.1016/j.cscm.2024.e04177","DOIUrl":"10.1016/j.cscm.2024.e04177","url":null,"abstract":"<div><div>The nonlinear assessment of masonry buildings strengthened with composites is crucial for evaluating retrofitting effectiveness prior to practical implementation. However, numerical tools for analyzing cost-efficient solutions like ferrocement remain scarce. The present study addresses this gap by introducing a simple yet effective 3D macro-modeling approach for simulating ferrocement-strengthened masonry structures. At first, the proposed finite element (FE) model was validated against experimental data, demonstrating its reliability in replicating the lateral load behavior. The validated model was then used to evaluate the efficacy of an optimal ferrocement strengthening configuration implemented in a ‘Splint and Bandage’ arrangement based on standardized guidelines. Relevant material properties essential for this investigation was comprehensively evaluated and utilized in the numerical model. The analysis revealed significant improvements in lateral load performance, including enhanced strength, ductility, and energy absorption capacity, with negligible impact on structural stiffness due to minimal added mass. Additionally, the strengthening effectively transformed the failure mode from a mixed compression-shear-flexural mechanism to a stable flexural rocking mode, significantly reducing stress concentrations and masonry damage. This study demonstrates the effectiveness of ferrocement bands as a cost-effective strengthening solution for unreinforced masonry buildings in seismically active regions. The findings provide valuable insights for optimizing ferrocement strengthening designs, making this approach particularly relevant for improving the lateral load performance of vulnerable masonry structures.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"22 ","pages":"Article e04177"},"PeriodicalIF":6.5,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143146186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of mechanical properties and cracking resistance of shrinkage-compensating concrete reinforced by expansive agents with polypropylene fibers","authors":"Wenxiao Lu ,&nbsp;Ji Chen ,&nbsp;Qiang Tang ,&nbsp;Fan Gu","doi":"10.1016/j.cscm.2024.e04171","DOIUrl":"10.1016/j.cscm.2024.e04171","url":null,"abstract":"<div><div>Concrete sidewalls are crucial in construction, yet their deformation control during casting and curing due to heat dissipation is a significant challenge. This often leads to issues such as shrinkage and cracking, which can compromise the structural integrity and functionality of the sidewalls. To overcome these issues, this study aimed to investigate the feasibility of adding expansion agent (EXP) and polypropylene fiber (PPF) to concrete for shrinkage compensation and crack resistance. A series of laboratory tests, including slump, compressive strength, flexural strength, X-Ray diffraction (XRD), and scanning electron microscope (SEM) tests, were carried out to analyze the mechanical properties and cracking-resistance mechanism of EXP and PPF reinforced concrete. Furthermore, a full-scale concrete sidewall was constructed, and sensor monitoring was implemented to measure temperature, stress, and strain variations. Numerical simulation of crack developing process was also conducted. The results showed that EXP reduced the early-age concrete strength but had a negligible effect on the final strength. Both EXP and PPF enhanced the ductility of concrete. The optimal mix was identified as concrete with 9 % EXP and 0.3 % PPF, exhibiting desirable compressive and flexural strengths and adequate ductility. The sensor monitoring of the full-scale sidewall showed that the internal temperature variation could reach 40 °C during curing, indicating that EXP alleviated heat from hydration and compensated for concrete shrinkage. Both the full-scale monitoring and numerical simulation results confirmed that the combined use of EXP and PPF enhanced the ductility of concrete and prevented the generation and propagation of microcracks in the concrete sidewall.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"22 ","pages":"Article e04171"},"PeriodicalIF":6.5,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of modified phosphogypsum on the dimensional stability of supersulfated cement-based materials","authors":"Qingqing Jin ,&nbsp;Lu Wang ,&nbsp;Zhisheng Ren ,&nbsp;Xinyu Li ,&nbsp;Shuhua Liu","doi":"10.1016/j.cscm.2024.e04170","DOIUrl":"10.1016/j.cscm.2024.e04170","url":null,"abstract":"<div><div>Compared to ordinary Portland cement (OPC), supersulfated cement (SSC) is an environmentally friendly cement. Phosphogypsum (PG) is commonly utilized as a sulfate activator in SSC. In this study, the effect of modified PG on the dimensional stability of supersulfated cement-based materials (SSCM) was investigated. Taking the point of decrease in internal relative humidity as the time-zero of autogenous shrinkage, the lime neutralized PG (NPG) reduced the autogenous shrinkage of SSCM by 15.03 % at 28 days and 16.26 % at 90 days, suppressing the development of autogenous shrinkage in SSCM. However, the calcined PG (CPG) displayed the opposite trend. Both modified PG improved the drying shrinkage of SSCM, and the NPG resulted in less water loss. Compared to OPC, SSCM exhibited a rapid increase in autogenous shrinkage relative to drying shrinkage, which was intensified with CPG. Obviously, the NPG demonstrated superior modification effects on the dimensional stability of SSCM compared to CPG.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"22 ","pages":"Article e04170"},"PeriodicalIF":6.5,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143146184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}