Cement and Concrete Composites最新文献

{"title":"Understanding the role of C-S-H seeds and sulfate in the lightweight cementitious composites containing fly ash cenospheres","authors":"Wenxiang Cao, Xuesen Lv, Xingang Wang, Jian-Xin Lu, Juhyuk Moon, Fubing Zou, Weichen Tian, Chi Sun Poon","doi":"10.1016/j.cemconcomp.2025.106150","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106150","url":null,"abstract":"Matrix strength and interfacial bonding between aggregate and matrix are critical factors influencing the performance of lightweight cementitious composites (LCC). This study proposes an environmentally friendly and efficient strategy for developing high-performance fly ash cenospheres (FAC)-containing LCC by combining sodium sulfate (SS) and calcium-silicate-hydrate (C-S-H) seeds. Moreover, the roles of SS and C-S-H seeds on achieving superior strength of LCC were elaborated by characterizing the hydration, microstructure, pore structure, and interfacial zone. Results show that the combined use of C-S-H seeds and SS accelerated silicate and aluminate hydration, shortened the setting time of LCC, and refined the pore size. FAC particles provided a nucleation site for the precipitation of ettringite due to the increased aluminum concentration and formation of gypsum on interface. Furthermore, C-S-H seeds and SS significantly improved the interfacial zone between FAC and matrix due to the enhanced pozzolanic reactivity of FAC. C-S-H seeds and SS primarily functioned through a physical nucleation and chemical activation to improve the matrix strength and interfacial zone, respectively, resulting in a high-performance LCC. Consequently, remarkable increases of 131.4 ± 19.8% and 29.0 ± 5.1% in early and late compressive strength of LCC were achieved. These findings present a novel approach for developing high-strength lightweight concrete with enhanced early strength under ambient curing.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"59 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Highly activated pozzolanic materials to develop sustainable concrete: a new perspective from photoexcited nano-TiO2","authors":"Jihong Jiang, Yanchun Miao, Qianping Ran, Yali Li, Yunjian Li, Zongshuo Tao, Zeyu Lu","doi":"10.1016/j.cemconcomp.2025.106149","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106149","url":null,"abstract":"Fly ash, a by-product of coal combustion, is a pozzolanic solid waste with annual production of 1.63 billion tonnes, which has been widely used to replace cement clinker to develop sustainable concrete. However, the incorporation of high volumes of inert fly ash significantly reduces the early mechanical strength of concrete due to its low pozzolanic activity. This study presents an innovative strategy to effectively enhance the reactivity of fly ash by utilizing hydroxyl free radicals (•OH), highly reactive oxidative species generated by nano-TiO₂ under UV light excitation. Experimental results demonstrated that photoexcited nano-TiO₂ significantly promoted the depolymerization of inert glassy phases in fly ash, resulting in a 28% increase in Ca(OH)₂ consumption within 72 hours. Consequently, the compressive and flexural strengths of mortar at 28 days increased by 37% and 16%, respectively, with a strength activity index reaching 95.4%. In addition, the water absorption and chloride ion diffusion coefficient were reduced by 15% and 18%, respectively, due to a more refined pore structure driven by enhanced pozzolanic reactivity. Density Functional Theory (DFT) calculations further revealed that •OH substantially lowered the energy barrier for Si-O-Al bonds cleavage (from 22.93 kcal/mol for OH^- to 8.54 kcal/mol for •OH), confirming its superior catalytic efficiency and thermodynamic advantage. In conclusion, the findings confirm that photoexcited nano-TiO₂ can serve as an effective activator for enhancing the utilization efficiency of fly ash in sustainable concrete.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synergistic reinforcement of recycled carbon fibers and biochar in high-performance, low-carbon cement composites: a sustainable pathway for construction materials","authors":"Huanyu Li, Ning Zhang, Jian Yang, Lei Wang, Thomas Köberle, Viktor Mechtcherine","doi":"10.1016/j.cemconcomp.2025.106148","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106148","url":null,"abstract":"The integration of biochar as a sustainable reinforcement in cementitious composites has emerged as a dual-benefit strategy for carbon sequestration and biomass waste management in the construction industry. However, excessive biochar incorporation often compromises the mechanical properties of cement matrices. This study introduces an innovative, eco-friendly approach by synergistically combining biochar (2%–10% cement replacement) with recycled carbon fibers (1%–3%) to develop high-performance, low-carbon cement mortars. Experimental findings reveal that while the biochar addition reduces fluidity and prolongs setting times, it enhances the cement hydration degree through nucleation effects, internal curing, and accelerated CO₂ diffusion, promoting the formation of ettringite, calcium silicate hydrate gels, and the carbonation process. Despite improvements in flexural strength, biochar-induced porosity negatively impacts compressive strength. The incorporation of recycled carbon fibers counteracts this limitation, significantly enhancing the compressive and flexural strengths of biochar-augmented mortars by up to 14% and 62%, respectively, compared to plain cement matrices, through fiber bridging mechanisms. Although a strong interfacial bond is observed between the fibers and the biochar-modified matrices, the reinforcing efficiency diminishes with higher biochar dosages. Furthermore, the fiber and biochar contents should be limited to specific amounts to avoid excessive porosity and the resulting strength loss. Additionally, incorporating 10% biochar alone into cementitious composites (10BC) provides the most favorable balance of environmental and economic performance under compressive strength criteria, achieving an emission reduction of 3.7 kg CO₂ eq./m³/MPa and a profit of 10.3 CNY/m³/MPa. Further enhancement is possible by adding 2% recycled carbon fiber to the 10BC mortar, increasing the total emission reduction to 41.1 kg CO₂ eq./m³/MPa when both compressive and flexural strengths are considered—albeit with a reduction in economic profitability. This study not only advances the development of low-carbon, high-strength building materials but also paves the way for the scalable application of biochar in the construction sector.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144136939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calcined clays for climate neutral (“net zero”) cements: shear-dependent rheological behavior and application performance","authors":"Jiaxin Chen, Johann Plank","doi":"10.1016/j.cemconcomp.2025.106145","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106145","url":null,"abstract":"The performance of low-carbon cements prepared from different neat calcined clays (CCs) can be very inconsistent due to substantial variations in the composition of the CC samples. To gain a better understanding and further promote the practical application of such low-carbon cements incorporating CCs, the influence of calcined clays possessing different mineralogical compositions on the rheological behavior of the blended cements was investigated. First, the shear-dependent rheology of pastes preparing from four types of CCs (1:1 and 1:2 type) blended with OPC at 70:30 and 30:70 wt./wt. ratios was elucidated. As it is well established that mortar tests are more representative for the behavior of actual concrete than cement paste, the rheological properties of OPC/CC mortars were evaluated via spread flow, flow line and V-funnel empty time tests. An industrial precast type HPEG (methallyl ether) PCE and a non-ionic co-dispersant were employed as dispersants. It was found that incorporation of CC greatly influences packing density and water film thickness of the composite cements. Moreover, performance of the blended cements significantly depends on the physio-chemical properties of the individual CCs, e.g. their particle size distribution, morphology and surface chemistry. To elucidate the underlying mechanism, PCE adsorption and surface charge (zeta potential) of the CC composite cements were determined, and a correlation between effectiveness of the PCE and its adsorbed amount per BET specific surface area of the binder was revealed.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144137185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel insight into the physical implication of percolation threshold of cement suspensions from microscopic and macroscopic perspectives","authors":"Xiaohan Yu, Jiaping Liu, Le Teng, Xin Shu, Chen Chen, Xin Liu","doi":"10.1016/j.cemconcomp.2025.106146","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106146","url":null,"abstract":"The percolation threshold plays a significant role in influencing the yield stress of cement-based materials. However, this crucial parameter has not been well understood given the absence of robust and reliable experimental methods and computing models. This study estimates the percolation threshold through regression analysis of yield stress and reveals its physical implications from the microscopic and macroscopic perspectives. The results indicate that the regression approach does not capture the theoretical percolation threshold, but rather a rigidity percolation threshold. The rigidity percolation threshold, reflecting the formation of a mechanically stable interaction network, is governed by the balance between colloidal forces and dominant separating force, either gravity or Brownian force. In cement pastes where gravity dominates over Brownian motion, the rigidity percolation threshold is significantly higher than the theoretical percolation threshold. A power-law relationship has been established between rigidity and theoretical percolation thresholds where the exponent is dependent on the gravitational Péclet number. In pastes containing large amounts of finer particles, where Brownian motion exceeds gravity, the rigidity percolation threshold aligns with the theoretical percolation threshold. From a macroscopic perspective, the rigidity percolation threshold is directly linked to the bleeding of cement pastes. A reduction in the solid volume fraction below the rigidity percolation threshold can result in bleeding, since the insufficient cement grains cannot form an internal particle network to resist gravity.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144130270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of aggregate distribution on the cracking behavior of concrete: A discrete element method study","authors":"Zesen Peng, Qing-feng Liu, Xuan Gao, Xin-Yu Zhao, Jin Xia, Qing-xiang Xiong","doi":"10.1016/j.cemconcomp.2025.106119","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106119","url":null,"abstract":"The aggregate distribution in concrete significantly influences the location of Interfacial Transition Zones (ITZs), impacting the initiation and propagation paths of cracks and complicating the prediction of concrete’s cracking behavior. To figure out the effects of aggregate distribution on concrete crack features, this study constructs a porosity-based heterogeneous model using the Discrete Element Method (DEM), considering the weak mechanical properties within the ITZs to accurately represent concrete crack evolution. Statistical analysis is then conducted to investigate the effects of aggregate distribution on the uniaxial compressive performance of concrete. The results indicate a linear relationship between the average compressive stress increment and the cracking proportion during the inelastic stage of concrete. Cracks are less likely to form between aggregates that are distributed along the loading direction. Furthermore, the length and endpoint positions of cracks between each pair of aggregates are determined within a specific range. Based on these statistical results, a crack prediction algorithm is proposed, and its key parameters are determined. Comparing the predicted crack patterns with those obtained from DEM modeling results demonstrates the algorithm’s accuracy in predicting the primary cracks in concrete subjected to uniaxial compression. This study hopes to provide a reference for predicting crack features in concrete with different aggregate distributions, facilitating more accurate assessments of structural damage and enhancing the safety and service life of concrete structures.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"117 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143940291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Self-healing assessment of fibre reinforced cementitious mortars developed for 3D concrete printing: recovery of mechanical performance and self-sealing capability","authors":"Behzad Zahabizadeh, João Pereira, Eduardo N.B. Pereira, Vítor M.C. F. Cunha","doi":"10.1016/j.cemconcomp.2025.106113","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106113","url":null,"abstract":"This study investigated the self-healing capability of two fibre reinforced cementitious mortars, with and without crystalline admixture, which were specifically developed for 3D concrete printing. Four-point bending tests were carried out to assess the recovery of mechanical properties, focusing on resistance and stiffness recovery indexes. Two residual crack opening displacements of 50 μm and 500 μm were imposed on the different series of the specimens to compare their influence on the self-healing capability. Crack self-sealing efficiency was investigated by capturing crack images using a digital microscope. In addition to the assessment of the self-healing efficiency over time, the relationship between mechanical recovery indexes and average crack widths, as well as the relationship between different recovery indexes were also studied. The results showed a higher recovery performance for mixtures with crystalline admixture in the case of stiffness recovery and self-sealing capabilities. Moreover, the results showed a decreased on the healing efficiency with the increase of the crack widths.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"110 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143926963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative Analysis of Pore Structures and Microcracks in Self-Healing Concrete after Freeze-Thaw Exposure: An X-Ray Computed Tomography-based Approach","authors":"Jialuo He, Yong Deng, Xianming Shi","doi":"10.1016/j.cemconcomp.2025.106105","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2025.106105","url":null,"abstract":"X-ray computed tomography (CT) is a valuable tool for investigating the microstructure of concrete. This study introduces a method for analyzing the pore structures and microcracks of self-healing concrete after 300 freeze/thaw (F/T) cycles using CT images with a relatively low resolution of 18.08 μm. Urea-formaldehyde microcapsules alone and in combination with polyvinyl alcohol microfibers were able to reduce 39.1% and 65.5% of the microcracks, respectively. Our approach involves calculating the total porosity and identifying constituents within the damaged pore structure based on geometric characteristics, employing the concepts of both circularity and roundness to discriminate intact pores, microcracks, and small/large-size pores with microcracks. The method’s reliability is validated by comparing the total porosity results with the mercury intrusion porosimetry data. Our approach provides an effective tool for quantitative evaluation of the microstructure of self-healing concrete under freeze-thaw conditions, paving the way for more efficient and cost-effective analyses of concrete durability.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143909912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of MgAl–NO2-LDHs on passivation of reinforcing steel in simulated geopolymer solution","authors":"Yuchen Wu, Zhipeng Xu, Jiangwei Zhu, Fengjiang Li, Jie Hu, Yuwei Ma, Zuhua Zhang, Haoliang Huang, Jiangxiong Wei, Qijun Yu, Caijun Shi","doi":"10.1016/j.cemconcomp.2024.105676","DOIUrl":"https://doi.org/10.1016/j.cemconcomp.2024.105676","url":null,"abstract":"Because of ion exchange properties, the presence of layered double hydroxides (LDHs) influences passivation process of reinforcement embedded in geopolymer concrete. In this study, the ion exchange behavior of MgAl–NO-LDHs and its effect on the characteristics of passivation film and electrochemical behavior of passive reinforcement in simulated slag-fly ash-waste ceramic powders geopolymer solution (SGP) are extensively investigated. The results indicate that LDHs with layered structure improve the protection efficiency of adsorption layer in SGP. Further, the intercalated NO is efficiently exchanged with OH in SGP, thus increasing the thickness and corrosion resistance of the formed passivation film. However, because the adsorption layer halts NO release process, the beneficial effect is mainly observed during later immersion stage.","PeriodicalId":519419,"journal":{"name":"Cement and Concrete Composites","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141836819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}