Shack Yee Hiew , Keat Bin Teoh , Sudharshan N. Raman , Chung-Chan Hung , Doo-Yeol Yoo , Kuo-Wei Wen , Daniel Kong , Yen Lei Voo
{"title":"3D micro-CT driven fibre orientation–confinement correlation model for ultra-high-performance concrete (UHPC)","authors":"Shack Yee Hiew , Keat Bin Teoh , Sudharshan N. Raman , Chung-Chan Hung , Doo-Yeol Yoo , Kuo-Wei Wen , Daniel Kong , Yen Lei Voo","doi":"10.1016/j.cemconcomp.2025.106081","DOIUrl":"10.1016/j.cemconcomp.2025.106081","url":null,"abstract":"<div><div>Accurately characterising steel fibres is paramount for developing a representative confinement model for Ultra-High-Performance Concrete (UHPC). Existing models oversimplify the fibre contributions by assuming a singular orientation, which fails to reflect the material variation resulting from actual fibre distribution. In this study, the authors refined the fibre orientation characteristics to establish a correlation with the confined core capacity at the structural level. To achieve this, multi-scale investigations, from experimental testing to X-ray micro-computed tomography (micro-CT) imaging on steel-confined UHPC specimens, were conducted, by varying internal (fibre types and contents) and external confinement pressures. A novel framework was developed to calibrate effective fibre orientation under varying fibre contents. This led to the introduction, for the first time, of a reliable fibre orientation model for UHPC subjected to varying confinement levels. The proposed model provided accurate predictions of the confined core capacity, aligning well with both scanned and unscanned specimens.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"161 ","pages":"Article 106081"},"PeriodicalIF":10.8,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143857275","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}
{"title":"Time dependence of corrosion resistance in belitic calcium sulfoaluminate (BCSA) cement concrete","authors":"Tayyab Adnan , Éric P. Bescher , Robert J. Thomas","doi":"10.1016/j.cemconcomp.2025.106099","DOIUrl":"10.1016/j.cemconcomp.2025.106099","url":null,"abstract":"<div><div>This paper studies the time dependence of corrosion resistance in belitic calcium sulfoaluminate (BCSA) cement concrete. BCSA is a hydraulic cement that sets rapidly and has a lower carbon footprint than portland cement (PC). Some studies suggest that BCSA concrete is highly susceptible to chloride-induced corrosion, but these claims are based on testing at 28 days. No later-age results have been reported. We confirm that BCSA cement concrete exhibits poor corrosion resistance when tested at 28 days, which can be attributed to an immature microstructure with weak resistance to chloride ingress and a pore solution that does not support passivation. We further show that corrosion resistance improves significantly as the BCSA system matures, achieving good corrosion resistance between 90 and 180 days. This improvement relates to the slow hydration of belite, which results in significant later-age microstructure refinement and probably alters the pore solution in a way that promotes or enhances steel passivation.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"161 ","pages":"Article 106099"},"PeriodicalIF":10.8,"publicationDate":"2025-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853348","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}
{"title":"Effect of TiO2/montmorillonite on the photocatalytic and mechanical properties of cementitious materials","authors":"Junjie Zhang , Yuzhe Li , Hongbo Tan","doi":"10.1016/j.cemconcomp.2025.106098","DOIUrl":"10.1016/j.cemconcomp.2025.106098","url":null,"abstract":"<div><div>The poor dispersion of nano-TiO<sub>2</sub> adversely affects the photocatalytic performance of photocatalytic cementitious materials (PCMs). In this study, a supported composite photocatalyst TiO<sub>2</sub>/montmorillonite (TiO<sub>2</sub>/Mt) was employed to prepare PCMs, aiming to improve the dispersion behavior of nano-TiO<sub>2</sub>. The impact of TiO<sub>2</sub>/Mt on the photocatalytic and mechanical properties of cementitious materials was also evaluated. The dispersion state of nano-TiO<sub>2</sub> was assessed through changes in particle size and zeta potential. The hydration process of PCMs was analyzed using hydration heat, X-ray diffractometer (XRD), and <sup>29</sup>Si-nuclear magnetic resonance (<sup>29</sup>Si-NMR), while the microstructure was examined by scanning electron microscope (SEM) and mercury intrusion porosimeter (MIP). Results indicated that, compared to TiO<sub>2</sub>-PCMs (P25-PCMs), the methylene blue (MB)/NO removal capacity of TiO<sub>2</sub>/Mt-PCMs was promoted, attributed to the improved dispersion state of nano-TiO<sub>2</sub> in cementitious materials. It was observed that TiO<sub>2</sub>/Mt exhibited significant agglomeration in the cementitious liquid phase due to the strong electrostatic attraction of calcium ions. However, the presence of PCE effectively mitigated this agglomeration through complexation and spatial site resistance effects. Additionally, the compressive strength of cementitious materials was significantly enhanced with the addition of TiO<sub>2</sub>/Mt. The nucleation effect of nanoparticles in TiO<sub>2</sub>/Mt shortened the induction period and accelerated hydrate formation. Furthermore, the excellent filling effect of TiO<sub>2</sub>/Mt reduced the porosity. This research provides valuable insights into achieving uniform dispersion of nano-TiO<sub>2</sub> in cementitious materials.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"161 ","pages":"Article 106098"},"PeriodicalIF":10.8,"publicationDate":"2025-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853347","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}
Yanshuai Wang , Hao Ye , Rongxin Peng , Xiangping Xian , Shuxian Hong
{"title":"Characterization and analysis of the self-healing behavior of alkali-activated slag mortar","authors":"Yanshuai Wang , Hao Ye , Rongxin Peng , Xiangping Xian , Shuxian Hong","doi":"10.1016/j.cemconcomp.2025.106097","DOIUrl":"10.1016/j.cemconcomp.2025.106097","url":null,"abstract":"<div><div>Alkali-activated slag (AAS) mortar has substantial limitations owing to its autogenous shrinkage, which leads to crack formation, and the self-healing property presents a promising solution to maintain its integrity and durability. Based on this, the self-healing efficiency of AAS mortar under a stable alkaline environment was assessed, with exogenous calcium ions introduced via a Ca(OH)<sub>2</sub> solution, and the self-healing mechanism was investigated with exogenous carbonate ions introduced to promote carbonation. To evaluate the effectiveness of these methods, both the physical properties and the microstructural characteristics of the AAS mortar under different healing environments were analyzed. The results revealed that self-healing environments, including secondary alkali activation and carbonation, substantially improved the rates of compressive strength recovery to 97.96 % and permeability recovery to 32.1 %. AAS mortar samples immersed in a saturated Ca(OH)<sub>2</sub> solution with wet-dry cycles, as well as those alternatingly immersed in Ca(OH)<sub>2</sub> and Na<sub>2</sub>CO<sub>3</sub> showed higher matrix-crack bond strength recovery rates (43.7 % and 23.1 %, respectively) than samples exposed to only a saturated Ca(OH)<sub>2</sub> solution (11.4 %). The predominant healing products, including CaCO<sub>3</sub> and calcium aluminum silicate hydrate, effectively bonded to the cracks, contributing to significant recovery of the physical properties. Thus, the optimal self-healing of the AAS mortar requires an alkaline environment with abundant calcium ions to improve CaCO<sub>3</sub> precipitation. Additionally, continuous carbonation with exogenous carbonate ions further improves the healing efficiency.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"161 ","pages":"Article 106097"},"PeriodicalIF":10.8,"publicationDate":"2025-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853346","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}
{"title":"Insights on solid CO2 mixing method for hybrid alkaline cement (HAC): performance, sustainability, and experimental system improvement","authors":"Yi-Sheng Wang , Runsheng Lin , Xiao-Yong Wang","doi":"10.1016/j.cemconcomp.2025.106096","DOIUrl":"10.1016/j.cemconcomp.2025.106096","url":null,"abstract":"<div><div>New low-carbon concrete materials and technologies are urgently needed to reduce CO<sub>2</sub> emissions and achieve sustainable development in the cement industry. Hybrid alkaline cement (HAC) is a new cement-based material that combines the advantages of ordinary Portland cement and alkali-activated cement. This study introduces a solid CO<sub>2</sub> mixing method and investigated its impact on the performance and sustainability of HAC. Research results show that the initial internal temperature of HAC decreases after solid CO<sub>2</sub> is mixed. The temperature gradually increased and surpassed that of the control sample within 12 h. The sequestration of solid CO<sub>2</sub> triggers a carbonation reaction within the material, leading to a reduction in calcium hydroxide and an increase in calcium carbonate content. An increase in solid CO<sub>2</sub> leads to a decrease in workability. Tests lasting up to 90 days demonstrated that the method substantially enhanced the strength and resistivity of HAC. This study considers two boundary conditions due to CO<sub>2</sub> escape when quantifying the CO<sub>2</sub> emissions of HAC and clarifies the specific levels under actual dose and optimized dose scenarios. The findings demonstrate the potential of the solid CO<sub>2</sub> mixing method to optimize material performance while highlighting its dual impact on sustainability. In addition, this study proposes an experimental idea for recovering the escaped CO<sub>2</sub> and using it for carbonation curing. These findings provide valuable insights and practical foundations for advancing the concrete industry to achieve sustainable development.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"161 ","pages":"Article 106096"},"PeriodicalIF":10.8,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143849968","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}
{"title":"Insight into the boundary flow resistance of high-workable concrete in different states: placing and pumping","authors":"Shijun Yuan , Zhisong Xu , Tengfei Feng , Jiaping Liu","doi":"10.1016/j.cemconcomp.2025.106094","DOIUrl":"10.1016/j.cemconcomp.2025.106094","url":null,"abstract":"<div><div>The flow resistance of modern high-workable concrete during pumping is usually considered linearly related to the flow rate, but some studies have found a non-linear relationship. An accurate assessment model of concrete flow resistance at different flow rates remains unclear. This study presents a methodology for calculating the boundary resistance of high-workable concrete based on other flow velocity ranges during the pumping and placing of the concrete. A modified interfacial rheometer was developed, and a particular test procedure was applied to test the flow resistance of 18 groups of high-workable concretes. The flow resistance changes during the increasing and decreasing stages of the flow speed were comprehensively analyzed. Both hydrodynamic interactions and particle friction characteristics have been considered. The results show a two-state linear relationship between boundary resistance and flow speed, corresponding to low flow speed (LFS, for placing) and high flow speed (HFS, for pumping). Finer sand, higher mortar volume, and a specific aggregate ratio reduce the viscous resistance constant, while a higher roundness of CA reduces the slip yield stress. Boundary resistance increases linearly with the interfacial self-friction coefficient, highlighting particle properties' critical role in flow resistance. This study reveals the origin of flow resistance and the factors affecting the interface rheological properties at different flow states and provides valuable insights for optimizing the pumping.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"161 ","pages":"Article 106094"},"PeriodicalIF":10.8,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143841221","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}
Mohammad Bakhshi, Isabel B. Valente, Honeyeh Ramezansefat, Joaquim A.O. Barros
{"title":"Effect of inertia and test approach on the high-strain-rate tensile behavior of steel fiber reinforced concrete","authors":"Mohammad Bakhshi, Isabel B. Valente, Honeyeh Ramezansefat, Joaquim A.O. Barros","doi":"10.1016/j.cemconcomp.2025.106095","DOIUrl":"10.1016/j.cemconcomp.2025.106095","url":null,"abstract":"<div><div>High strain rate loadings lead to fundamental modifications in the tensile stress-strain response of steel fiber-reinforced concrete (SFRC). These modifications include higher tensile strength and corresponding strain and fracture energy. This paper investigates the effect of strain rate on the tensile behavior of SFRC, covering ranges from quasi-static (10<sup>−6</sup> to 10<sup>−1</sup> s<sup>−1</sup>) to impact (10–50 s<sup>−1</sup>). For this purpose, an instrumented drop-weight test setup was developed. The instrumentation includes a high-speed response data acquisition, a high-speed video camera, two fast response load cells, one clip gauge, and two strain gauges. Axial and transversal inertia effects were considered during the impact process to reach the real tensile behavior of SFRC. The effects of strain rate on the stress–strain and stress versus cracking opening displacement relations, tensile strength, and fracture energy of SFRC are obtained and discussed in both quasi-static and impact ranges. Novel models are proposed for predicting the strain rate effect on the tensile strength and fracture energy of SFRC, considering the type of tensile load applied. The models proposed in the current study are compared with the experimental results obtained within this research and those available in other studies. The findings demonstrate that incorporating the influence of inertia and employing the proposed models for the testing approach markedly enhances the accuracy in predicting the dynamic tensile behavior of SFRC.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"161 ","pages":"Article 106095"},"PeriodicalIF":10.8,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143837121","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}
{"title":"Effect of mix design factors on the self-stress-sensing behavior of metakaolin-based geopolymer","authors":"Krishnan U. Ambikakumari Sanalkumar, En-Hua Yang","doi":"10.1016/j.cemconcomp.2025.106093","DOIUrl":"10.1016/j.cemconcomp.2025.106093","url":null,"abstract":"<div><div>The present study investigates the influence of mix design ratios on the self-sensing behavior of geopolymer pastes. The increase in silicate content, corresponding to high alkali content, leads to higher self-sensing, mechanical strength, and lower resistivity. The alterations in mix design ratios result in modifications to the ions in the pore solution and microstructure of the geopolymer, which are accountable for the variations in self-sensing behavior and electrical performance. The study demonstrates a correlation between the sensing coefficient, determined by the changes in resistivity, and the compressive strength and electrical resistivity. Among the mix design ratios, SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> ratio is determined to be the most substantial parameter regarding the self-sensing behavior of geopolymer. The findings suggest that geopolymer has the potential for self-sensing applications without the requirement for supplementary conductive fillers or fibers.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"161 ","pages":"Article 106093"},"PeriodicalIF":10.8,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143831763","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}
Júlio Jorge Braga de Carvalho Nunes , Felipe Rodrigues de Souza , Pablo Augusto Krahl , Rebecca Mansur de Castro Silva , Pâmela Pires de Paula , Flávio de Andrade Silva
{"title":"Low-velocity impact behavior of functionally graded cement-based composites: Combining SFRC, UHPC and textile-reinforced UHPC","authors":"Júlio Jorge Braga de Carvalho Nunes , Felipe Rodrigues de Souza , Pablo Augusto Krahl , Rebecca Mansur de Castro Silva , Pâmela Pires de Paula , Flávio de Andrade Silva","doi":"10.1016/j.cemconcomp.2025.106079","DOIUrl":"10.1016/j.cemconcomp.2025.106079","url":null,"abstract":"<div><div>Functionally graded cement-based materials can be designed to exhibit high energy dissipation capacity by applying materials in specific positions according to the loading protocol. A layer of Ultra-High-Performance Concrete (UHPC) combined with carbon textiles positioned in the most critical zone is a promising solution to improve the behavior of cement-based composites against impact, which has not yet been fully clarified. This study presents a novel two-layer composite approach, combining Steel Fiber Reinforced Concrete (SFRC) with UHPC and carbon textiles, tested under drop weight impact. Three different energy levels were investigated: 112.8, 225.6, and 338.4 J. The UHPC thin layers were reinforced with smooth or steel hooked end fibers, and a group was combined with Textile Reinforced Concrete (TRC). SFRC and UHPC were cast simultaneously, improving the bond between the matrices. The results highlight that SFRC + UHPC with steel hooked fibers have better impact performance than SFRC + UHPC with smooth fibers, exhibiting better crack opening control, higher impact resistance, and lower deflection. Additionally, the same trend was observed when the UHPC layer was reinforced with TRC, which demonstrated a significant reduction in residual displacements and crack openings, as well as improved energy absorption capacity, with increases of up to 370% compared to conventional specimens, highlighting their potential for high-impact applications.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"161 ","pages":"Article 106079"},"PeriodicalIF":10.8,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143827213","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}
Hanbing Zhao , Yixiang Gan , Fulin Qu , Zhuo Tang , Shuhua Peng , Yangqiao Chen , Wengui Li
{"title":"Nano- and micro-characterisation on the heterogeneity of ITZs in recycled lump concrete","authors":"Hanbing Zhao , Yixiang Gan , Fulin Qu , Zhuo Tang , Shuhua Peng , Yangqiao Chen , Wengui Li","doi":"10.1016/j.cemconcomp.2025.106078","DOIUrl":"10.1016/j.cemconcomp.2025.106078","url":null,"abstract":"<div><div>Recycled lump concrete (RLC) is a new sustainable construction material for filling large-sized demolished concrete lump (DCL) piles with fresh mortar or concrete. Due to the differences from conventional concrete casting technology, the heterogeneity and cohesion performance of the interfacial transition zones (ITZs) require further investigation. In this study, two types of self-compacting mortar (SCPM) were designed using blends of cement, recycled sand/recycled powder (RS/RP), and fly ash as raw materials. The filling performance of the SCPM was evaluated based on the microstructure, micromechanical properties and phase distribution within the ITZs and the adjacent matrix surrounding DCLs. Both types of SCPM effectively fill the gaps between DCLs, observed in the appearance of specimens. However, the bonding strength of bottom and oblique bottom ITZs of RLC prepared by SCPM without fly ash and superplasticizer was poor, making it impossible to produce ITZ samples from these two locations successfully. The heterogeneity and cohesion strength of the ITZs surrounding the DCLs depends on the distribution of pores and grains. Grains, including RP and fly ash, accumulated at the top and oblique top sides of the DCL due to sedimentation. Fly ash and RP effectively promoted the healing of micro-pores and cracks around DCLs but had a limited effect on pores and cracks with an average equivalent diameter greater than 1 μm. In summary, the ITZs at the top and oblique top sides of the DCLs had a denser microstructure and better bonding performance than those at other locations around the DCLs.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"161 ","pages":"Article 106078"},"PeriodicalIF":10.8,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143823025","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}