Case Studies in Construction Materials最新文献

{"title":"Flexural behavior of the fast-hardening anti-disturbance concrete wet-joint beam after vibration of solidification period","authors":"Chang Liu ,&nbsp;Jinsheng Du ,&nbsp;Ziang Sun ,&nbsp;Licun Yu ,&nbsp;Yuzhuo Wang","doi":"10.1016/j.cscm.2025.e04921","DOIUrl":"10.1016/j.cscm.2025.e04921","url":null,"abstract":"<div><div>This paper presented the flexural behavior of the fast-hardening anti-disturbance concrete (FHADC) wet-joint beam after vibration of solidification period. Considering the influence factors of amplitude and frequency, 10 FHADC wet-joint beams were vibrated during solidification, then the beams were subjected to bending test. The results showed that: (1)The failure mode of wet-joint beams was bending-shear failure. (2)Simple harmonic vibration can cause more serious damage on beams, compared with low-cycle reciprocating vibration. The crack size increase with the increasing amplitude and frequency of the applied vibration. (3)Under low-cycle reciprocating vibration, the ultimate load of beam decreased by 1.8 % with the amplitude increased. (4)Under simple harmonic vibration, the ultimate load of beam decreased by 36.8 % with the increase of amplitude and decreased by 20.4 % with the increase of frequency. Finally, a calculation method for the flexural capacity of wet-joint beams has been proposed, which offers a reference for similar engineering design.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"23 ","pages":"Article e04921"},"PeriodicalIF":6.5,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144364396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of curing temperature and age on the mechanical properties and damage law of coal-based solid waste cemented backfill","authors":"Xiang He ,&nbsp;Longqiang Wei ,&nbsp;Ke Yang ,&nbsp;Zhiqiang Wen ,&nbsp;Lianfu Zhang ,&nbsp;Yongqiang Hou","doi":"10.1016/j.cscm.2025.e04937","DOIUrl":"10.1016/j.cscm.2025.e04937","url":null,"abstract":"<div><div>Backfilling the underground caved zones with coal-based solid waste allows large-scale disposal of the waste and abates overburden damage. Since the curing temperature and age play an essential role in affecting the strength of the backfill, the uniaxial compression test, acoustic emission damage monitoring, and microscopic scanning electron microscopy were carried out on the standard cube specimens with the curing temperature of 20, 27, 35, 42.5 and 50 °C (accompanied by the curing age of 3, 7, 14 and 28 days, respectively). The microstructure evolution and damage constitutive model of coal-based waste cemented backfill (CWCB) were discussed to reveal how CWCB strength develops. The results demonstrate that: (1) The increase of curing age and temperature would underpin the mechanical properties of CWCB, since the maximum strength reached 5.45 MPa, with the curing temperature of 42.5 °C and the curing age of 28 days. (2) A curing temperature of 50 °C inflicted physical and mechanical damage on the bonding interface of the backfill. As shown by the microscopic morphology comparison (20, 27, 35, and 42.5 °C), more irregular structures inside the specimens were resulted from excessive hydration reaction. This defect triggered a dramatic ascent in the acoustic emission ringing count at 28 days of age, jeopardizing the strength to merely 76 % of that at 42.5 °C, while macroscopically, the failure was manifested as an X-shaped conjugate inclined plane shear pattern. (3) The temperature-dependent segmented damage constitutive model established based on the Weibull distribution was in good agreement with the experimental stress-strain curve. The damage-strain curve reflects three phases: slow increase, steep rise, and slow down, which correspond to the plastic deformation, damage failure and residual stages, respectively, in the stress-strain curve.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"23 ","pages":"Article e04937"},"PeriodicalIF":6.5,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144306942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flexural behavior of shield tunnel lining segments reinforced using grouted channel steel: Experimental investigation","authors":"Kan Huang ,&nbsp;Xun Wu ,&nbsp;Jun He ,&nbsp;Bin Huang ,&nbsp;Yi Peng ,&nbsp;Kaidi Zhou","doi":"10.1016/j.cscm.2025.e04922","DOIUrl":"10.1016/j.cscm.2025.e04922","url":null,"abstract":"<div><div>This study examines a reinforcement method using grouted channel steel for damaged shield tunnel lining segments in urban rail transit systems. Full-scale experiments were conducted to analyze the flexural failure mechanism and evaluate the performance improvement of damaged segments before and after reinforcement. The results demonstrate the effectiveness of the proposed method in enhancing structural capacity and extending service life. Underpinned by the elastic and plastic theory, a calculation method has been developed to identify the cracking load and load-bearing capacity of segments before and after reinforcement. This method has been further validated through comparisons with full-scale loading tests. Results indicate that the grouted channel steel reinforcement could significantly enhance the load-bearing capacity of damaged segments, the ultimate load has been promoted by approximately 33 % and the ultimate deformation resistance has been improved by 57.3 %. The method effectively prolongs the elastic and plastic phases of damaged segments while limiting crack width growth. The discrepancy between theoretical calculations and experimental results is within 10 %, demonstrating high accuracy. The developed calculation method provides a reliable strategy to evaluate the structural condition of tunnel segments under diverse loading conditions, both before and after damage and reinforcement.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"23 ","pages":"Article e04922"},"PeriodicalIF":6.5,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance of thermally modified wood strands and thin veneers for use in durable mass timber panels","authors":"Rajan Adhikari ,&nbsp;Avishek Chanda ,&nbsp;Muhammad Khusairy Bin Bakri ,&nbsp;Modupe Morenike Akinnuoye ,&nbsp;Manuel Raul Pelaez-Samaniego ,&nbsp;Matthew Aro ,&nbsp;Vikram Yadama","doi":"10.1016/j.cscm.2025.e04920","DOIUrl":"10.1016/j.cscm.2025.e04920","url":null,"abstract":"<div><div>The innovative structural composite material, proposed in this study, offers an opportunity to repurpose low-value, small-diameter trees by adopting strand-based technology into their production. Furthermore, the thermal modification of wood strands provides a natural alternative to chemical treatments, ensuring the production of dimensionally stable and durable mass timber products. In this study, to demonstrate the scaling up of the thermal modification process, the mechanical and physical performance of thermally modified (TM) wood strands subjected to varying temperatures and pressures in an industrial autoclave were evaluated, and their efficacy in producing thin wood-strand veneer composite materials was evaluated. Wood strands from low-grade spruce-pine-fir lumber were thermally modified at peak temperatures of 165°C, 170°C, and 180°C, keeping a constant pressure of 1.4 MPa, and at 165°C with 0.8 MPa. A dwell time of 2 h at these conditions was used in all treatments. The process was conducted using an industrial autoclave (12 m³ volume) with nitrogen gas. Based on the results, the treatment at 0.8 MPa and 165°C yielded strands with suitable quality and performance to produce composite panels. Driven largely by hemicellulose degradation and their partial extraction, a 35 % reduction in the equilibrium moisture content and 21 % increase in contact angle of the treated strands was observed along with no significant variation in tensile modulus, about 52 % reduction in tensile strength, and 91 % increase in brittleness index. TM wood strands produced veneers with improved bond performance and dimensional stability, where a reduction in thickness swelling of up to 38 %, an increase in internal bond strength by 37 %, no significant variation in flexural stiffness, a decrease in flexural strength by 37 %, and an increase in brittleness index by 54 % in the veneers were observed.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"23 ","pages":"Article e04920"},"PeriodicalIF":6.5,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of pore shape on uniaxial compressive behaviour of porous rock-like materials: DEM simulation","authors":"Chuanfeng Fang ,&nbsp;Tieyong Zhao ,&nbsp;Weijian Yu ,&nbsp;Ping Wang ,&nbsp;Zizheng Zhang ,&nbsp;Baifu An ,&nbsp;Genshui Wu ,&nbsp;Shunkai Liu","doi":"10.1016/j.cscm.2025.e04938","DOIUrl":"10.1016/j.cscm.2025.e04938","url":null,"abstract":"<div><div>The pore shapes of porous rock-like materials are not circular but complex and diverse，constituting a critical factor influencing their mechanical properties and failure characteristics. In this study, the effects of pore angularity and aspect ratio on the mechanical behaviour of porous rock-like materials under uniaxial compression were quantitatively analyzed using the Discrete Element Method (DEM). Numerical models containing pores of various shapes were constructed as Voronoi polygon aggregates to more realistically simulate material fracture. The results show that with increasing angularity or aspect ratio, both the uniaxial compressive strength and elastic modulus decrease in distinct patterns, while Poisson's ratio remains unchanged. Moreover, higher angularity or aspect ratio not only leads to cracks initiation at sharp corners and causes the crack paths to deviate from the axial loading direction, but also results in an increase in both the total crack length and the number of fragments. Finally, the evolution of the microstructure, including contact forces and the spatial distribution of stress, was analyzed to assess the influence of pore shape on microscopic characteristics.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"23 ","pages":"Article e04938"},"PeriodicalIF":6.5,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assimilating nanographene into the pervious concrete - surface treatment for enhanced paving performance","authors":"Ivana Barišić ,&nbsp;Ivanka Netinger Grubeša ,&nbsp;Milica Vasić ,&nbsp;Aleksandar Janaćković","doi":"10.1016/j.cscm.2025.e04917","DOIUrl":"10.1016/j.cscm.2025.e04917","url":null,"abstract":"<div><div>This research aims to assess the impact of surface treatment with a nanographene solution on the properties of pervious concrete paving flags (PC paving flags). Four different methods of applying the nanographene solution were examined: spraying, submerging, double submerging, and brushing. The properties of the PC paving flags, as specified by EN 1339, were tested, including bending strength/breaking load, water absorption, abrasion resistance, unpolished slip resistance value (USRV) as well as porosity and permeability. To aid in the interpretation of the results, SEM analysis and optical microscopy were conducted. It is concluded that the surface treatment of PC paving flags with the nanographene solution resulted in a moderate increase in bending strength/breaking load and had a negligible impact on USRV and abrasion resistance values while reducing water absorption, total porosity, and permeability. Optical microscope images revealed that the nanographene treatment smoothed the surface of the PC paving flags sealing it and reducing open porosity. The sealed surface explained the observed reduction in water absorption while reduced open porosity clarified the reduction in total porosity and consequently, water absorption and permeability. The micrographics showed further evidence of the changes in mechanical strength and porosity introduced with nanographene and the presence of carbon on the surface. The elongated pores were present in all the samples, being largest in the sprayed sample.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"23 ","pages":"Article e04917"},"PeriodicalIF":6.5,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel methodology for indirect application of hydrophobic agents into cement matrix: Superabsorbent polymers (SAPs) as a delivery medium","authors":"Dalia Bednarska ,&nbsp;Alicja Wieczorek ,&nbsp;Julia von Werder","doi":"10.1016/j.cscm.2025.e04935","DOIUrl":"10.1016/j.cscm.2025.e04935","url":null,"abstract":"<div><div>Hydrophobic agents are one of the most commonly used means of prolonging the lifespan of cement-based materials. However, when water-repellent is added to the batch water it can interfere with cement hydration leading to deteriorated mechanical properties of the hardened material. To eliminate this drawback, a novel methodology of indirectly applying hydrophobic agents to cement-based materials is introduced. The presented approach uses super absorbent polymers (SAPs) as a delivery medium. SAP containing water-repellent is added to the fresh cement mixture, which ensures a gradual release of the admixture. The release is driven either by drying which generates moisture gradient or by compression of polymer particles by hydrates arising in their vicinity. Such mechanisms lead to a delayed dosage of the hydrophobic agent, which is when the partially hardened cement matrix is less vulnerable to interference compared to the fresh mixture. The effectiveness of the proposed methodology was verified in the extensive experimental program. Cement mortars of two water-to-cement ratios (0.4, and 0.5) were tested in terms of compressive strength, capillary absorption, and contact angle among others. Based on the obtained results it is concluded that the proposed methodology limits the negative impact of the hydrophobic agent on cement hydration. The mechanical performance of the samples modified with the indirectly dosed admixture is improved compared to the conventionally hydrophobized material in each analysed case. The results of isothermal calorimetry support the thesis. Additionally, the effectiveness of imparting hydrophobic characteristics to the cement matrix was as good as in the case of the conventional dosing. The mercury intrusion porosimetry, as well as thermogravimetric tests, were run to provide a deeper insight into the microstructure and composition of the modified material. Scanning electron microscopy was used to give a better insight into samples’ morphology. The novel methodology presented can also potentially be used to dose other types of admixtures that can interfere with cement hydration.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"23 ","pages":"Article e04935"},"PeriodicalIF":6.5,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144338757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiple-scaled investigations on mechanical properties of medium-early- strength PVA-ECC with recycled tire crumb rubber incorporated","authors":"Yuanchuan Chen ,&nbsp;Chenyu Lu ,&nbsp;Zhigang Zhang ,&nbsp;Jamal A. Abdalla ,&nbsp;Rami A. Hawileh ,&nbsp;Xiaoyue Zhang","doi":"10.1016/j.cscm.2025.e04931","DOIUrl":"10.1016/j.cscm.2025.e04931","url":null,"abstract":"<div><div>In recent years, significant attention has been directed toward advancing medium-early-strength engineered cementitious composites (MES-ECC), reflecting their growing importance in construction research. However, limited research has explored the fundamental principles governing the mechanical behavior of MES-ECC. This study systematically investigates the multi-scale effects of crumb rubber (CR) content and curing duration on the mechanical performance of MES-ECC. The results showed that the compressive strength and tensile strength of MES-ECC of 3 days at the macro-scale are reached more than 60 % of 28 days. The incorporation of CR in MES-ECC produced a characteristic trade-off between strength and ductility. While compressive strength showed measurable reduction, the MES-ECC demonstrated significantly enhanced deformation capacity through featuring greater the number of cracks and reduced crack widths at macroscopic scale. The pseudo-strain-hardening (<em>PSH</em>) value decreased with extended curing ages, correlating directly with the observed ductility reduction in MES-ECC. Notably, incorporating CR enhances the ductility and multiple cracking behavior of MES-ECC, successfully counteracting the detrimental impacts of reduced deformability.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"23 ","pages":"Article e04931"},"PeriodicalIF":6.5,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144291607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experiment and modelling of performance degradation of boric acid-corroded concrete in nuclear power plants","authors":"Hua Rong ,&nbsp;Yan Geng ,&nbsp;Jun Tao ,&nbsp;Xin-Zhu Zhou ,&nbsp;Jian-Jun Zheng ,&nbsp;Yu-Qiang Jia","doi":"10.1016/j.cscm.2025.e04932","DOIUrl":"10.1016/j.cscm.2025.e04932","url":null,"abstract":"<div><div>Borated water leaks out of spent fuel pools from time to time and degrades the performance of concrete support structures. Therefore, a comprehensive experiment is essential for exploring the degradation characteristics of concrete located in a boric acid environment. The purpose of this paper is to investigate the leaching depth, elastic modulus, and cube compressive strength of concrete immersed in boric acid solutions through experiment. The effects of immersion time, boric acid concentration, temperature, and water/binder ratio on the leaching depth, elastic modulus, and cube compressive strength of concrete are evaluated in a quantitative manner. Based on the experimental results, three models for the leaching depth, elastic modulus, and cube compressive strength of concrete are derived. One of the advantages of these models is that once the elastic modulus and cube compressive strength of sound concrete and the leaching depth are measured, the elastic modulus and cube compressive strength of boric acid-affected concrete can be evaluated. Finally, the validity of the three models is verified with experimental results.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"23 ","pages":"Article e04932"},"PeriodicalIF":6.5,"publicationDate":"2025-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144313462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving the post-fire performance of reinforced concrete beams with lightweight plaster","authors":"Daniel Paul Thanaraj ,&nbsp;Varun Sabu Sam ,&nbsp;N. Anand ,&nbsp;Diana Andrushia ,&nbsp;Katherine A. Cashell","doi":"10.1016/j.cscm.2025.e04918","DOIUrl":"10.1016/j.cscm.2025.e04918","url":null,"abstract":"<div><div>Structural fires pose significant risks to the built environment, making fire resistance a critical design consideration for reinforced concrete (RC) structures. Elevated temperatures during fires reduce the strength and stiffness of both concrete and steel reinforcement, compromising load-bearing capacity. This experimental study evaluates the effectiveness of lightweight plaster coatings in enhancing the post-fire performance of RC members exposed to ISO 834 standard fire conditions. Two materials, expanded vermiculite (EV) and expanded perlite (EP), were examined. First, the compressive strength of concrete mixes incorporating EV or EP as partial replacements (2.5 %, 5 %, 7.5 %, and 10 %) for fine aggregates was assessed after heating durations of 30–120 min. Subsequently, structural performance was tested in RC beams across three configurations: (1) EV or EP integrated into the mix, (2) EV or EP applied as external plaster, and (3) a combination of both. A total of 54 RC beam specimens were cast, with 12 beams used for internal temperature monitoring and 42 subjected to four-point bending tests following 60, 90, and 120 min of heating. Concrete grades M20 and M50 were developed using EV or EP as partial sand replacements, while plaster layers were prepared with EV or EP mortar. Key performance indicators, including load-deflection response, ultimate load, internal temperature distribution, residual rebar yield strength, and first-crack load, were analysed. The protected M20-EP+EPC beam recorded a 62.2 % reduction in rebar temperature compared to the unprotected M20-R beam. Further, the loss of yield strength was reduced by 87.5 %, and the moment of resistance degradation was reduced by 61.1 % compared to the unprotected M20-R beam. Beams protected with EV or EP in both the mix and external plaster demonstrated superior performance, extending survival time from 45 to 120 min and improving fire resistance ratings from 15 to 60 min based on insulation criteria.</div></div>","PeriodicalId":9641,"journal":{"name":"Case Studies in Construction Materials","volume":"23 ","pages":"Article e04918"},"PeriodicalIF":6.5,"publicationDate":"2025-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144364387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}