Cement and Concrete Research最新文献

{"title":"Chloride transport, binding, and microstructure in alkali-activated concrete with different types of precursor combinations","authors":"Zuobang Yao ,&nbsp;Ram Pal ,&nbsp;Haemin Song ,&nbsp;Arthur Van de Keere ,&nbsp;Ali Kashani ,&nbsp;Elke Gruyaert ,&nbsp;Taehwan Kim","doi":"10.1016/j.cemconres.2025.108002","DOIUrl":"10.1016/j.cemconres.2025.108002","url":null,"abstract":"<div><div>This paper presented the experimental results of investigating chloride resistance and the microstructure of alkali-activated concrete (AAC). To show the reliable and efficient chloride transport analyses for AAC, a modified rapid chloride penetration test using 10 V was validated, and the conventional chloride profile methods were compared with the newly developed micro X-ray fluorescence (μXRF) profile method. Six AAC mixtures incorporating different precursors were evaluated for mechanical strength, water absorption, chloride diffusion, and binding. At the same content of ground granulated blast furnace slag in mixtures, the precursor incorporating calcined bauxite tailings and rice husk ash increased porosity and reduced chloride resistance compared to that containing fly ash. This study revealed that chloride binding in all AAC used in this study was predominantly physical and reversible, contrasting with Portland cement systems. μXRF technique provided reliable and spatially resolved chloride profile data for AAC. This study provides valuable insights into AAC performance and testing, emphasising the importance of precursor selection for sustainable AAC.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"198 ","pages":"Article 108002"},"PeriodicalIF":10.9,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694944","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":"An experimental and numerical study of alkali-activated fly ash paste – from dissolution kinetics to microstructure formation","authors":"Yun Chen ,&nbsp;Jiayi Chen ,&nbsp;Mayank Gupta ,&nbsp;Xuhui Liang ,&nbsp;Luiz Miranda de Lima ,&nbsp;Zhiyuan Xu ,&nbsp;Yibing Zuo ,&nbsp;Suhong Yin ,&nbsp;Qijun Yu ,&nbsp;Guang Ye","doi":"10.1016/j.cemconres.2025.107999","DOIUrl":"10.1016/j.cemconres.2025.107999","url":null,"abstract":"<div><div>This study presents an extended numerical approach based on GeoMicro3D to simulate the reaction kinetics and three-dimensional (3D) microstructure evolution of alkali-activated fly ash (AAFA). Dissolution experiments were conducted under varying NaOH concentrations and temperatures to formulate predictive rate functions for Si and Al release. These experimentally derived kinetic functions, alongside a thermodynamic dataset for N-(C-)A-S-H gels, were incorporated into the GeoMicro3D model to capture the chemical reactions and 3D microstructure evolution of AAFA. The model well captured reaction degree of fly ash, formation of solid products, evolution of pore solution compositions, and porosity over time. Notably, it is the first to predict the time-dependent spatial distribution of phases within the 3D AAFA microstructure by integrating kinetic and microstructural modeling. Dual validation using both dissolution data and microstructural metrics demonstrates the model's reliability and robustness. This integrated framework provides new insights into the coupled chemical–microstructural evolution of alkali-activated materials.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"198 ","pages":"Article 107999"},"PeriodicalIF":10.9,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144678281","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":"Assignment of SiO vibrational modes in the IR spectra of C-S-H phases based on single-crystal polarized IR and Raman spectra of 14 Å tobermorite, jennite, and jaffeite","authors":"Krassimir Garbev ,&nbsp;Biliana Gasharova ,&nbsp;Angela Ullrich ,&nbsp;Günter Beuchle ,&nbsp;Peter Stemmermann","doi":"10.1016/j.cemconres.2025.108000","DOIUrl":"10.1016/j.cemconres.2025.108000","url":null,"abstract":"<div><div>This article explains the vibrational modes in the Si<img>O stretching range in the IR spectra of synthetic C-S-H phases with varying C/S ratios. These are compared with selected <em>in situ</em> spectra of hydrates of OPC, and those of synthetic crystalline hydrates. The assignments were supported by ²⁹Si NMR and trimethylsilylation (TMS) data. IR and Raman polarized spectra of oriented crystals of 14 Å tobermorite, jennite and jaffeite enabled direct observation of the Si<img>O vibrational modes. They were successfully resolved based on the involvement of specific silicon (paired, bridging) and oxygen (bridging, non-bridging) atoms, and were compared with existing theoretical data. The resemblance between the IR spectra of synthetic C-S-H and those formed upon hydration of OPC, proves the suitability of model C-S-H phases for understanding hydration processes. Some uncertainties in the assignment of the C-S-H bands observed in existing <em>in situ</em> IR experiments are discussed, and potential sources of error identified.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"198 ","pages":"Article 108000"},"PeriodicalIF":10.9,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144678275","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":"Inhibition of tricalcium aluminate hydrate–sulfate interactions by size and content-dependent silica particles","authors":"Zhaoheng Guo ,&nbsp;Cheng Liu ,&nbsp;Xu Luo ,&nbsp;Gaofeng Chen ,&nbsp;Huixia Wu ,&nbsp;Zhenhai Xu ,&nbsp;Shujun Li ,&nbsp;Jianming Gao ,&nbsp;Yasong Zhao ,&nbsp;Hongjian Du","doi":"10.1016/j.cemconres.2025.108001","DOIUrl":"10.1016/j.cemconres.2025.108001","url":null,"abstract":"<div><div>The incorporation of nanoscale or microscale silica into cementitious materials has been demonstrated to markedly enhance resistance to sulfate attack. Despite this benefit, the exact mechanisms responsible for these improvements are not yet fully understood, particularly concerning the role of unhydrated silica particles in blended cement under sulfate exposure. Tricalcium aluminate (C₃A), a key component of cement, contributes a substantial proportion of the aluminum phases that are vulnerable to sulfate attack. The present study investigated how silica particles of varying sizes influence the interactions between C₃A hydrates and sulfate solutions. By conducting qualitative and quantitative analyses of the reaction products, microstructural morphology, ion concentrations, zeta potentials, and sulfate concentrations in the solution, a new impact mechanism model was developed. These findings reveal that nanoscale silica (NS) particles in the C₃A hydrates and the sulfate system impede the reaction between hydrogarnet and sulfate, thereby reducing ettringite formation. NS mainly suppresses hydrogarnet dissolution, resulting in lower concentrations of Ca²⁺ and Al³⁺ ions and reduced consumption of SO₄²⁻ ions. This suppression is attributed to the adsorption of NS on the hydrogarnet surface, and NS attracts Ca²⁺, SO₄²⁻ ions, or Ca<img>S ion pairs, leading to surface ion overcharging and thereby reducing hydrogarnet dissolution. In addition, NS particles adhere to the surface of ettringite, preventing the adsorption of Ca²⁺, SO₄²⁻, or Ca<img>S ion pairs, thereby inhibiting ettringite formation and growth. This effect is notably dependent on the presence of NS, as microscale silica or insufficient quantities of NS lessen or eliminate the impact. These findings provide insights into the use of nanomaterials to enhance the durability of cement-based materials and establish a foundational basis for future research in this area.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"198 ","pages":"Article 108001"},"PeriodicalIF":10.9,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144671016","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":"Understanding early hydration in belite calcium sulfoaluminate cements: Impacts of minor elements and citric acid","authors":"Imane Koufany ,&nbsp;Jaime Fernandez-Sanchez ,&nbsp;Ana Cuesta ,&nbsp;Isabel Santacruz ,&nbsp;Eric P. Bescher ,&nbsp;Miguel A.G. Aranda ,&nbsp;Angeles G. De la Torre","doi":"10.1016/j.cemconres.2025.107982","DOIUrl":"10.1016/j.cemconres.2025.107982","url":null,"abstract":"<div><div>This study investigates the early-age hydration behavior of eight belite calcium sulfoaluminate (BCSA) cement batches with nearly identical compositions and physical properties, yet exhibiting significantly different hydration kinetics. Two clusters were identified: relatively fast-setting cements with a final setting time of 22 min and a main calorimetric peak at 2 h, and relatively slow-setting cements with 28-minute setting times and peaks at 3 h. These values can be retarded by adding citric acid. The fast-setting cements displayed higher early concentrations of soluble potassium (149 mM) and sulfate (76 mM) than slow-setting cements (107 mM and 57 mM, respectively), attributed to greater potassium sulfate content. Higher alkaline content accelerates ye'elimite dissolution and hasten ettringite crystallization. Isothermal calorimetry and in-situ laboratory X-ray powder diffraction (analyzed via Rietveld refinement) confirmed that the differences in dissolution and crystallization kinetics underlie the observed variability. The addition of citric acid extended both initial and final setting times by approximately 1.8 h. Its retarding effect was most pronounced for anhydrite dissolution, with a smaller impact on ye'elimite dissolution and AFt crystallization. Pore solution analysis revealed that citric acid increased calcium and sulfate concentrations while reducing potassium levels, supporting a retardation mechanism involving calcium complexation and preferential sorption/deposition of citrate onto anhydrous phases. These findings underscore the importance of early-age phase-specific dissolution behavior in governing BCSA cement performance, particularly for applications requiring rapid setting and early strength development.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"198 ","pages":"Article 107982"},"PeriodicalIF":10.9,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144669782","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":"Mechanistic insights into calcium-silicate-hydrate nucleation from molecular dynamics simulations","authors":"Jon López-Zorrilla ,&nbsp;Eduardo Duque-Redondo ,&nbsp;Pablo Martin ,&nbsp;Jiale Huang ,&nbsp;Xabier M. Aretxabaleta ,&nbsp;Juan J. Gaitero ,&nbsp;Hegoi Manzano","doi":"10.1016/j.cemconres.2025.107979","DOIUrl":"10.1016/j.cemconres.2025.107979","url":null,"abstract":"<div><div>The nucleation and growth of C-S-H play a prominent role in cement hydration and the microstructure development of hardened cement paste. Understanding the nucleation could enable control of the kinetics of the process, for instance designing more efficient additives. Unfortunately, experimental characterization and computational modeling of nucleation remain challenging. In this work, molecular dynamics simulations were used to investigate the formation of C-S-H aggregates from initial primary particles (PPs) in solution. Starting with a dimeric PP obtained from Evolutionary Algorithms, simulations were performed with varying Ca(OH)₂ concentrations. The results show that calcium accelerates the assemblage into stable aggregates, releasing water molecules in the process. The size and density of the PPs and aggregates are compared with recent experimental data, revealing discrepancies for complexes and PPs, but better agreement for aggregates and globules. This study provides insights, and opens new questions, on the identification of nucleation pathways of C-S-H.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"198 ","pages":"Article 107979"},"PeriodicalIF":10.9,"publicationDate":"2025-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144662873","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":"Advanced modelling of moisture transport process in unsaturated cementitious materials considering multi-modal pore size distributions","authors":"Liang-yu Tong ,&nbsp;Qing Xiang Xiong ,&nbsp;Xinyuan Ke ,&nbsp;Natalia Mariel Alderete ,&nbsp;Nele De Belie ,&nbsp;Qing-feng Liu","doi":"10.1016/j.cemconres.2025.107973","DOIUrl":"10.1016/j.cemconres.2025.107973","url":null,"abstract":"<div><div>Moisture permeation in unsaturated cementitious materials is highly related to the pore structure characteristics. The present study carries out a novel pore-scale analysis to quantitatively establish the relationship between pore structure features and water vapour sorption isotherms, and develops a microstructure-based model for predicting the moisture transport in cementitious materials, considering multi-modal lognormal pore size distributions. A key innovation of this study is the introduction of a new S-shaped function to characterize the fraction of trapped water due to the pore-blocking effect during desorption, highlighting its strong dependence on the peak pore size. The predicted water vapour sorption isotherms—accounting for both pore-blocking and cavitation mechanisms—along with relative permeabilities and internal moisture distributions during adsorption and desorption, were validated against experimental data, showing good agreement. The findings reveal that a denser pore structure will contain a relatively higher water saturation degree at the same relative humidity. Furthermore, the results emphasize that a multi-modal pore size distribution model provides a more comprehensive representation of moisture transport behaviour compared to the conventional single-modal approach. By bridging pore-scale mechanisms with macro-scale transport modelling, this study proposes an advanced numerical approach for investigating moisture transport in cementitious materials.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"198 ","pages":"Article 107973"},"PeriodicalIF":10.9,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144656326","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":"Enhancing the rheology, reaction kinetics and early-age strength of limestone calcined clay cement (LC3) with sodium silicate addition","authors":"Xiaodi Dai ,&nbsp;Marcus Yio ,&nbsp;Haoming Wu ,&nbsp;Susan Bernal Lopez ,&nbsp;Chris Cheeseman ,&nbsp;Hong S. Wong","doi":"10.1016/j.cemconres.2025.107997","DOIUrl":"10.1016/j.cemconres.2025.107997","url":null,"abstract":"<div><div>The effect of small-dose sodium silicate (SS) solutions with varying compositions on the rheology and early-age strength of limestone calcined clay cement (LC³) was evaluated. SS addition reduced colloidal interactions in LC³, leading to significant reductions in initial yield stress and viscosity, depending on composition. All SS-added systems met the initial setting time requirements of EN 197–1. A solution containing 1 % Na₂O and a silicate modulus of 0.4 notably accelerated silicate and aluminate reactions in cement clinker, as well as synergistic reactions between calcined clay and limestone. This resulted in 1-day strength gains of 120 % and 13 % compared to LC³ and CEM I, respectively. Microstructural analysis revealed a denser matrix and refined pore structure at 1 day, consistent with accelerated phase evolution. These results demonstrate that well-formulated SS solutions can significantly enhance both rheology and early-age performance of LC³, supporting their use as effective accelerators in sustainable cement systems.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"198 ","pages":"Article 107997"},"PeriodicalIF":10.9,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144633248","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":"Tensile properties and self-healing mechanism of pre-cracked UHPC under different curing environments","authors":"Yiming Yao ,&nbsp;Xun Lin ,&nbsp;Can Chen ,&nbsp;Hongrui Zhang ,&nbsp;Sijing Chen ,&nbsp;Hangyu Zhou ,&nbsp;Tianyu Wang ,&nbsp;Barzin Mobasher","doi":"10.1016/j.cemconres.2025.107985","DOIUrl":"10.1016/j.cemconres.2025.107985","url":null,"abstract":"<div><div>This study investigates the effects of curing environments, age, and initial crack width on the self-healing performance of pre-cracked UHPC. Direct tensile tests were conducted using crack width as a quantitative index for damage and healing. Results showed significant recovery in tensile strength, with all specimens surpassing the control group after 56 days. Single fiber pull-out tests revealed temperature-dependent interfacial effects: a 60 °C water bath enhanced secondary hydration but also accelerated steel fiber corrosion, altering the failure mode from pull-out to fracture. Microstructural changes were examined via thermal analysis, X-CT, and SEM, confirming that water baths promoted hydration and densification. However, surface crack healing hindered internal hydration by limiting moisture and CO₂ ingress. A multi-scale analysis linked macroscopic tensile recovery to microscopic mechanisms. Additionally, a theoretical model based on hydration kinetics and the Arrhenius equation was proposed to estimate healable crack width, providing predictions that aligned well with experimental data.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"198 ","pages":"Article 107985"},"PeriodicalIF":10.9,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144630032","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":"Mechanistic insights into microstructural changes caused by stapling in extrusion-based 3D printed concrete (3DPC)","authors":"Rijiao Yang ,&nbsp;Chengji Xu ,&nbsp;Sen Fang ,&nbsp;Xinze Li ,&nbsp;Yu Peng ,&nbsp;Zhendi Wang ,&nbsp;Qiang Zeng","doi":"10.1016/j.cemconres.2025.107998","DOIUrl":"10.1016/j.cemconres.2025.107998","url":null,"abstract":"<div><div>Stapling is an effective post-implantation method for reinforcing three-dimensional (3D) printed concrete (3DPC); however, it may alter the microstructure of the adjacent concrete slurry. To uncover the mechanisms of microstructural alterations induced by stapling, remaining inadequately understood, we comprehensively characterized the microstructure of extrusion-based 3DPC with two viscosity levels, stapled using steels of five different diameters. The results suggest that the anchoring effect of the staples enhanced the interlayer bonding, while the formation of the staple-matrix interfacial defects decreased the compressive strength. These defects were non-uniformly distributed along the staples, and the 3DPC with higher viscosity exhibited more severe defects. The contribution of staple-matrix defects to mechanical strength was assessed based on defect ratio and connected length. Finally, a model was developed to capture the deformation of concrete slurry during the stapling process. These findings deepen the mechanistic understanding of the conflict between stapling reinforcement and interfacial weakness in 3DPC.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"198 ","pages":"Article 107998"},"PeriodicalIF":10.9,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144630162","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}