Pub Date : 2026-01-09DOI: 10.1016/j.cemconres.2026.108132
Thilo Schmid , O. Burkan Isgor , Ueli Angst
Corrosion of steel in concrete involves complex transport and (electro-) chemical processes at the steel–concrete interface (SCI). Reactive transport modeling is a powerful tool to investigate these mechanisms and has strong potential to provide critical insights into corrosion-related deterioration and thereby contribute to ensuring the durability of traditional and modern low-carbon concretes. Traditional reactive transport models use homogenization techniques that are computationally efficient but overlook the detailed pore structure at the SCI. Our study introduces an approach that leverages high-resolution FIB-SEM nanotomograms to create discretized finite element domains, enabling direct pore-scale reactive transport modeling. We showcase selected examples involving aqueous species relevant to corrosion, including corrosion product precipitation in the interfacial pore network. Simulation results demonstrate that pore structure gives rise to significant local variations in concentrations and precipitate formation, thereby explaining the heterogeneity of corrosion phenomena in cementitious materials. Notably, narrow pores acting as transport bottlenecks caused local aqueous accumulation, promoting precipitation in contrast to more open regions. For comparison, a homogenized model – using independently computed diffusion tortuosity and porosity from 3D pore structures – was implemented. Remarkably, without parameter fitting, this model captured average trends but failed to resolve key localized phenomena like early corrosion product precipitation. We conclude that explicitly modeling pore-scale structures is essential for accurately capturing reactive transport processes at the SCI. Our framework offers a path towards more accurate simulation of micron- and sub-micron scale processes, challenging simplifying assumptions in traditional models, and emphasizing the need for incorporating local structural features at the SCI in corrosion modeling.
{"title":"Pore-scale simulation of reactive transport processes at the steel–concrete interface","authors":"Thilo Schmid , O. Burkan Isgor , Ueli Angst","doi":"10.1016/j.cemconres.2026.108132","DOIUrl":"10.1016/j.cemconres.2026.108132","url":null,"abstract":"<div><div>Corrosion of steel in concrete involves complex transport and (electro-) chemical processes at the steel–concrete interface (SCI). Reactive transport modeling is a powerful tool to investigate these mechanisms and has strong potential to provide critical insights into corrosion-related deterioration and thereby contribute to ensuring the durability of traditional and modern low-carbon concretes. Traditional reactive transport models use homogenization techniques that are computationally efficient but overlook the detailed pore structure at the SCI. Our study introduces an approach that leverages high-resolution FIB-SEM nanotomograms to create discretized finite element domains, enabling direct pore-scale reactive transport modeling. We showcase selected examples involving aqueous species relevant to corrosion, including corrosion product precipitation in the interfacial pore network. Simulation results demonstrate that pore structure gives rise to significant local variations in concentrations and precipitate formation, thereby explaining the heterogeneity of corrosion phenomena in cementitious materials. Notably, narrow pores acting as transport bottlenecks caused local aqueous <figure><img></figure> accumulation, promoting <figure><img></figure> precipitation in contrast to more open regions. For comparison, a homogenized model – using independently computed diffusion tortuosity and porosity from 3D pore structures – was implemented. Remarkably, without parameter fitting, this model captured average trends but failed to resolve key localized phenomena like early corrosion product precipitation. We conclude that explicitly modeling pore-scale structures is essential for accurately capturing reactive transport processes at the SCI. Our framework offers a path towards more accurate simulation of micron- and sub-micron scale processes, challenging simplifying assumptions in traditional models, and emphasizing the need for incorporating local structural features at the SCI in corrosion modeling.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"202 ","pages":"Article 108132"},"PeriodicalIF":13.1,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923707","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}
Pub Date : 2026-01-08DOI: 10.1016/j.cemconres.2025.108131
Shunmin Xiao, Yi Jiang, Zihan Ma, Long Jiang, Jionghuang He, Qi Liu, Peiliang Shen, Chi Sun Poon
Alumina-silica gels are highly reactive pozzolans derived from the carbonation of solid waste containing calcium and aluminosilicate. Their microstructure and reactivity are critically influenced by the Al/Si ratio, which in turn varies greatly depending on the original composition of the raw materials. In this study, alumina-silica gels with Al/Si ratios of 0.01–0.91 were synthesized through a two-step carbonation process, aiming at revealing their differences in pozzolanic reactivity. Findings indicate that their pozzolanic reactivity and reaction pathways were governed by chemical composition, AlSi microstructural configuration, and resulting physical properties. An Al/Si ratio of 0.01 resulted in a gel with the highest porosity and specific surface area, as well as the lowest particle size. This gel rapidly formed C–S–H and nearly completed the reaction within 1 d, releasing the highest cumulative heat of 764.9 J/g during its reaction with calcium hydroxide. However, when the Al/Si ratio increased to 0.35, the gel reacted more slowly and exhibited two low-intensity exothermic peaks of 1.7 and 0.6 mW/g that were associated with C–A–S–H and strätlingite formation, respectively. Despite similar compositions and physical properties, gels differed in depolymerization and reaction rates. This was because the incorporation of Na acted as charge-balancing ions when Al tetrahedra replaced some of the Si tetrahedra. Particularly, for the gel with the highest Al/Si ratio of 0.91, its rich Na content greatly accelerated depolymerization. This caused a sharp increase in heat release between 12 and 60 h (218.2 J/g), with strätlingite as the main product.
{"title":"Effect of Al/Si ratio on the reactivity of waste- and two-step carbonation-derived alumina-silica gel","authors":"Shunmin Xiao, Yi Jiang, Zihan Ma, Long Jiang, Jionghuang He, Qi Liu, Peiliang Shen, Chi Sun Poon","doi":"10.1016/j.cemconres.2025.108131","DOIUrl":"10.1016/j.cemconres.2025.108131","url":null,"abstract":"<div><div>Alumina-silica gels are highly reactive pozzolans derived from the carbonation of solid waste containing calcium and aluminosilicate. Their microstructure and reactivity are critically influenced by the Al/Si ratio, which in turn varies greatly depending on the original composition of the raw materials. In this study, alumina-silica gels with Al/Si ratios of 0.01–0.91 were synthesized through a two-step carbonation process, aiming at revealing their differences in pozzolanic reactivity. Findings indicate that their pozzolanic reactivity and reaction pathways were governed by chemical composition, Al<img>Si microstructural configuration, and resulting physical properties. An Al/Si ratio of 0.01 resulted in a gel with the highest porosity and specific surface area, as well as the lowest particle size. This gel rapidly formed C–S–H and nearly completed the reaction within 1 d, releasing the highest cumulative heat of 764.9 J/g during its reaction with calcium hydroxide. However, when the Al/Si ratio increased to 0.35, the gel reacted more slowly and exhibited two low-intensity exothermic peaks of 1.7 and 0.6 mW/g that were associated with C–A–S–H and strätlingite formation, respectively. Despite similar compositions and physical properties, gels differed in depolymerization and reaction rates. This was because the incorporation of Na acted as charge-balancing ions when Al tetrahedra replaced some of the Si tetrahedra. Particularly, for the gel with the highest Al/Si ratio of 0.91, its rich Na content greatly accelerated depolymerization. This caused a sharp increase in heat release between 12 and 60 h (218.2 J/g), with strätlingite as the main product.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"202 ","pages":"Article 108131"},"PeriodicalIF":13.1,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145908792","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}
Pub Date : 2026-01-03DOI: 10.1016/j.cemconres.2025.108128
Shuai Ding , Cise Unluer , Kai Li , Yanlong Ren , Ning Li , Zhangli Hu , Jiaping Liu
MgO expansive agents (MEA) and fly ash (FA) are widely combined to mitigate shrinkage in concrete, yet their interaction mechanisms remain unclear. This study clarifies how FA regulates MEA-induced expansion through microstructural evolution and pore solution chemistry, with swelling and crystallization pressures identified as the driving forces. At early stages, FA lowered pH, elevated Mg2+ concentration, accelerating periclase hydration. Higher mesoporosity enlarged dissolution interface, promoted formation of finer brucite with stronger water adsorption capacity, increasing swelling pressure. At later stages, pozzolanic reaction of FA reduced portlandite formation, diminishing spatial confinement near MEA and alleviating crystallization pressure. Suppressed portlandite barriers and enhanced Mg2+ mobility promoted brucite precipitation into surrounding voids, refining pore structure and improving dimensional stability. This work extends understanding of MEA-induced deformation to a coupled chemical–microstructural level and shows that FA regulates expansion driving forces through ionic and microstructural interactions, establishing a framework for achieving full-stage shrinkage compensation.
{"title":"Unravelling chemical-microstructural pathways of deformation in MgO-fly ash cementitious systems","authors":"Shuai Ding , Cise Unluer , Kai Li , Yanlong Ren , Ning Li , Zhangli Hu , Jiaping Liu","doi":"10.1016/j.cemconres.2025.108128","DOIUrl":"10.1016/j.cemconres.2025.108128","url":null,"abstract":"<div><div>MgO expansive agents (MEA) and fly ash (FA) are widely combined to mitigate shrinkage in concrete, yet their interaction mechanisms remain unclear. This study clarifies how FA regulates MEA-induced expansion through microstructural evolution and pore solution chemistry, with swelling and crystallization pressures identified as the driving forces. At early stages, FA lowered pH, elevated Mg<sup>2+</sup> concentration, accelerating periclase hydration. Higher mesoporosity enlarged dissolution interface, promoted formation of finer brucite with stronger water adsorption capacity, increasing swelling pressure. At later stages, pozzolanic reaction of FA reduced portlandite formation, diminishing spatial confinement near MEA and alleviating crystallization pressure. Suppressed portlandite barriers and enhanced Mg<sup>2+</sup> mobility promoted brucite precipitation into surrounding voids, refining pore structure and improving dimensional stability. This work extends understanding of MEA-induced deformation to a coupled chemical–microstructural level and shows that FA regulates expansion driving forces through ionic and microstructural interactions, establishing a framework for achieving full-stage shrinkage compensation.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108128"},"PeriodicalIF":13.1,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880215","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}
Pub Date : 2026-01-02DOI: 10.1016/j.cemconres.2025.108127
Micael Rubens Cardoso da Silva , Jiahui Qi , Ian Ross , Ana Paula Kirchheim , Brant Walkley
The performance of superplasticisers in alkali-activated materials (AAMs) remains poorly understood, limiting the wider adoption of low-carbon cement technologies. This study examines the behaviour of lignosulfonate- (LS), naphthalene- (NP), and polycarboxylate ether (PCE)-based superplasticisers in NaOH/Na₂SiO₃-activated systems with ground granulated blast furnace slag (GGBFS) and metakaolin (MK). The adsorption phenomena and polymer conformation were investigated by combining mini-slump tests (flow behaviour), ATR-FTIR (chemical interactions), DLS (polymer size), TEM-EDX (polymer conformation), zeta potential measurements (surface charge), and total organic carbon analysis (polymer uptake). Results show that in both GGBFS and MK systems, high alkalinity alters polymer ionisation, suppresses electrostatic interactions, reduces superplasticiser solubility, and drives polymer agglomeration. In GGBFS systems, Ca2+ enhances superplasticiser adsorption to solid particles. LS-based superplasticisers demonstrated superior alkaline resistance, slump retention, and adsorption capacity relative to NP and PCE. These findings provide new mechanistic insights to guide the design of high-performance superplasticisers tailored for low-carbon AAM systems.
{"title":"Adsorption phenomena and surface interactions between superplasticisers and ground blast furnace slag and metakaolin particles in alkali solutions: Implications for low-carbon cements","authors":"Micael Rubens Cardoso da Silva , Jiahui Qi , Ian Ross , Ana Paula Kirchheim , Brant Walkley","doi":"10.1016/j.cemconres.2025.108127","DOIUrl":"10.1016/j.cemconres.2025.108127","url":null,"abstract":"<div><div>The performance of superplasticisers in alkali-activated materials (AAMs) remains poorly understood, limiting the wider adoption of low-carbon cement technologies. This study examines the behaviour of lignosulfonate- (LS), naphthalene- (NP), and polycarboxylate ether (PCE)-based superplasticisers in NaOH/Na₂SiO₃-activated systems with ground granulated blast furnace slag (GGBFS) and metakaolin (MK). The adsorption phenomena and polymer conformation were investigated by combining mini-slump tests (flow behaviour), ATR-FTIR (chemical interactions), DLS (polymer size), TEM-EDX (polymer conformation), zeta potential measurements (surface charge), and total organic carbon analysis (polymer uptake). Results show that in both GGBFS and MK systems, high alkalinity alters polymer ionisation, suppresses electrostatic interactions, reduces superplasticiser solubility, and drives polymer agglomeration. In GGBFS systems, Ca<sup>2+</sup> enhances superplasticiser adsorption to solid particles. LS-based superplasticisers demonstrated superior alkaline resistance, slump retention, and adsorption capacity relative to NP and PCE. These findings provide new mechanistic insights to guide the design of high-performance superplasticisers tailored for low-carbon AAM systems.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108127"},"PeriodicalIF":13.1,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880213","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}
Pub Date : 2025-12-30DOI: 10.1016/j.cemconres.2025.108121
Kai Cui , Danyang Zhao , Yingliang Zhao , Yong Zheng , Weiwei Wu , Qinglong Qin , Fenghua Nie , Jun Chang , Peiliang Shen , Chi Sun Poon
Calcium sulfoaluminate cement (CSA) often exhibits limited long-term strength due to the lack of suitable supplementary cementitious materials (SCMs) that can effectively promote secondary hydration. This study introduces a novel approach for preparing CO2 induced SCMs (CSCMs) derived from CSA, aiming to overcome this limitation and enhance both hydration kinetics and mechanical performance. CSCMs, produced by CO2 induced CSA for three hours, consist of polycrystalline calcium carbonate phases, specifically, aragonite (7.6 %), vaterite (2.1 %) and calcite (22.4 %), alongside amorphous AlSi gel. When incorporated into CSA at a dosage of 10 wt%, these CSCMs significantly accelerated hydration, resulting in increased formation of AFt and AH3, which boosted early compressive strength by 22.7 % in one day and 14.4 % at three days compared to control samples. Beyond early strength gains, the presence of CSCMs facilitated further reactions among calcium carbonate, AlSi gel, and C4A3Š, leading to the generation of Mc and Hc phases. These products stabilized AFt and contributed to improving compressive strength over extended curing periods. After 180 days, samples containing CSCMs exhibited strength increases of 26.1 % (5 % CSCMs), 31.8 % (10 % CSCMs), and 27.2 % (20 % CSCMs), while the control sample experienced a 5.9 % strength reduction and 8.2 % AFt decomposition. The enhanced performance is attributed to the high reactivity and nucleation effects of the calcium carbonate and AlSi gel components. This study developed low-cost CSCMs for dedicated CSA, while resolving the conflict between CSA strength development and carbon emission reduction.
{"title":"Development of CO2-induced SCMs for calcium sulfoaluminate cement: Towards enhancing hydration, compressive strength and later stage-ettringite stability","authors":"Kai Cui , Danyang Zhao , Yingliang Zhao , Yong Zheng , Weiwei Wu , Qinglong Qin , Fenghua Nie , Jun Chang , Peiliang Shen , Chi Sun Poon","doi":"10.1016/j.cemconres.2025.108121","DOIUrl":"10.1016/j.cemconres.2025.108121","url":null,"abstract":"<div><div>Calcium sulfoaluminate cement (CSA) often exhibits limited long-term strength due to the lack of suitable supplementary cementitious materials (SCMs) that can effectively promote secondary hydration. This study introduces a novel approach for preparing CO<sub>2</sub> induced SCMs (CSCMs) derived from CSA, aiming to overcome this limitation and enhance both hydration kinetics and mechanical performance. CSCMs, produced by CO<sub>2</sub> induced CSA for three hours, consist of polycrystalline calcium carbonate phases, specifically, aragonite (7.6 %), vaterite (2.1 %) and calcite (22.4 %), alongside amorphous Al<img>Si gel. When incorporated into CSA at a dosage of 10 wt%, these CSCMs significantly accelerated hydration, resulting in increased formation of AFt and AH<sub>3</sub>, which boosted early compressive strength by 22.7 % in one day and 14.4 % at three days compared to control samples. Beyond early strength gains, the presence of CSCMs facilitated further reactions among calcium carbonate, Al<img>Si gel, and C<sub>4</sub>A<sub>3</sub>Š, leading to the generation of Mc and Hc phases. These products stabilized AFt and contributed to improving compressive strength over extended curing periods. After 180 days, samples containing CSCMs exhibited strength increases of 26.1 % (5 % CSCMs), 31.8 % (10 % CSCMs), and 27.2 % (20 % CSCMs), while the control sample experienced a 5.9 % strength reduction and 8.2 % AFt decomposition. The enhanced performance is attributed to the high reactivity and nucleation effects of the calcium carbonate and Al<img>Si gel components. This study developed low-cost CSCMs for dedicated CSA, while resolving the conflict between CSA strength development and carbon emission reduction.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108121"},"PeriodicalIF":13.1,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880214","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}
Pub Date : 2025-12-24DOI: 10.1016/j.cemconres.2025.108126
Yizhou Zhao , Barbara Lothenbach , Zhangli Hu , Biwan Xu
The magnesium-to-KH2PO4 (Mg/PO₄) molar ratio is crucial for magnesium potassium phosphate (MKP) cement-based composites. To develop Ultra-High-Performance Cement-based Composite (UHPCC) using MKP cement, the effect of Mg/PO₄ molar ratios (4–8) on the properties and microstructure of steel fiber-reinforced MKP cement-based composites was investigated. Increasing the Mg/PO₄ ratio accelerated the hydration kinetics, without compromising flowability. The lowest molar ratio (Mg/PO₄ = 4) resulted in significant shrinkage, whereas ratios ≥6 induced slight expansion. The optimal molar ratio was determined to be Mg/PO4 = 7, which yielded a composite meeting UHPCC requirements, with 28-day compressive, flexural, and tensile strengths of ∼132 MPa, ∼ 44 MPa, and ∼ 14 MPa, respectively. The optimum properties achieved at this ratio can be attributed to the highest fiber-matrix bonding stress and a denser microstructure with a more rational composition, leading to higher local elastic modulus, increased hardness, and improved crack resistance.
{"title":"Optimizing Mg/PO4 molar ratio for ultra-high-performance steel fiber-reinforced magnesium potassium phosphate cement-based composite","authors":"Yizhou Zhao , Barbara Lothenbach , Zhangli Hu , Biwan Xu","doi":"10.1016/j.cemconres.2025.108126","DOIUrl":"10.1016/j.cemconres.2025.108126","url":null,"abstract":"<div><div>The magnesium-to-KH<sub>2</sub>PO<sub>4</sub> (Mg/PO₄) molar ratio is crucial for magnesium potassium phosphate (MKP) cement-based composites. To develop Ultra-High-Performance Cement-based Composite (UHPCC) using MKP cement, the effect of Mg/PO₄ molar ratios (4–8) on the properties and microstructure of steel fiber-reinforced MKP cement-based composites was investigated. Increasing the Mg/PO₄ ratio accelerated the hydration kinetics, without compromising flowability. The lowest molar ratio (Mg/PO₄ = 4) resulted in significant shrinkage, whereas ratios ≥6 induced slight expansion. The optimal molar ratio was determined to be Mg/PO<sub>4</sub> = 7, which yielded a composite meeting UHPCC requirements, with 28-day compressive, flexural, and tensile strengths of ∼132 MPa, ∼ 44 MPa, and ∼ 14 MPa, respectively. The optimum properties achieved at this ratio can be attributed to the highest fiber-matrix bonding stress and a denser microstructure with a more rational composition, leading to higher local elastic modulus, increased hardness, and improved crack resistance.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108126"},"PeriodicalIF":13.1,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145823220","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}
Pub Date : 2025-12-23DOI: 10.1016/j.cemconres.2025.108125
Peter J. McDonald , David A. Faux , Longfei Ma , Hong Wong
In recent years, 1H NMR relaxometry has become a mainstream methodology for study of the nano-porosity of cement-based materials. For the most part, measurements have been carried out using variants of the classic CPMG and solid-echo NMR pulse sequences and, to a lesser extent, the inversion recovery sequence.
Notwithstanding considerable successes, these methods all have one or another disadvantage, quite often associated with reliable differentiation of the so-called inter-layer and quasi-crystalline water fractions. In this paper, we introduce the application of the spin-lock experiment as a convenient alternative methodology. Early results are presented. Measuring overcomes some of the earlier difficulties, potentially has some wider advantages but also has raised some interesting questions of interpretation associated with the partitioning of water between C-S-H interlayer spaces and quasi-crystalline phases.
{"title":"1H NMR relaxation analysis of cement-based materials: The spin-lock T1ρ experiment and the partitioning of water in C-S-H inter-layer spaces","authors":"Peter J. McDonald , David A. Faux , Longfei Ma , Hong Wong","doi":"10.1016/j.cemconres.2025.108125","DOIUrl":"10.1016/j.cemconres.2025.108125","url":null,"abstract":"<div><div>In recent years, <sup>1</sup>H NMR relaxometry has become a mainstream methodology for study of the nano-porosity of cement-based materials. For the most part, measurements have been carried out using variants of the classic CPMG <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> and solid-echo NMR pulse sequences and, to a lesser extent, the inversion recovery <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> sequence.</div><div>Notwithstanding considerable successes, these methods all have one or another disadvantage, quite often associated with reliable differentiation of the so-called inter-layer and quasi-crystalline water fractions. In this paper, we introduce the application of the <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>1</mn><mi>ρ</mi></mrow></msub></math></span> spin-lock experiment as a convenient alternative methodology. Early results are presented. Measuring <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>1</mn><mi>ρ</mi></mrow></msub></math></span> overcomes some of the earlier difficulties, potentially has some wider advantages but also has raised some interesting questions of interpretation associated with the partitioning of water between C-S-H interlayer spaces and quasi-crystalline phases.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108125"},"PeriodicalIF":13.1,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145812863","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}
Pub Date : 2025-12-22DOI: 10.1016/j.cemconres.2025.108124
Weihuan Li , Chenchen Xiong , Yang Zhou , Yangzezhi Zheng , Jiarui Xing , Yanji Jin , Yulin Wang
Mineral dissolution is a critical phenomenon in various fields, particularly in the early hydration of Portland cement. Despite its importance, atomic-scale mechanisms remain elusive due to limitations in experimental and computational methods. Using an efficient sampling strategy that integrates metadynamics and targeted molecular dynamics, we developed a deep learning interatomic potential with quantum-level accuracy and scalable computational efficiency to reveal the dissolution mechanisms of tricalcium aluminate (C3A). The results uncover distinct dissociation pathways of calcium and aluminate ions. Specifically, Ca ions follow a ligand-exchange mechanism, preferentially transitioning to an unsaturated coordination state before bonding with water molecules. Conversely, Al ions first coordinate with water molecules to reach a supersaturated coordination state, which promotes the opening of six-membered rings and the cleavage of Al ions. This work elucidates the thermodynamics of C3A dissolution, deepening the understanding of mineral-water interfacial reactions, and provides an efficient, accurate approach for probing complex reaction pathways.
{"title":"Deciphering the initial hydration reaction of tricalcium aluminate based on Ab initio-accurate machine learning force field","authors":"Weihuan Li , Chenchen Xiong , Yang Zhou , Yangzezhi Zheng , Jiarui Xing , Yanji Jin , Yulin Wang","doi":"10.1016/j.cemconres.2025.108124","DOIUrl":"10.1016/j.cemconres.2025.108124","url":null,"abstract":"<div><div>Mineral dissolution is a critical phenomenon in various fields, particularly in the early hydration of Portland cement. Despite its importance, atomic-scale mechanisms remain elusive due to limitations in experimental and computational methods. Using an efficient sampling strategy that integrates metadynamics and targeted molecular dynamics, we developed a deep learning interatomic potential with quantum-level accuracy and scalable computational efficiency to reveal the dissolution mechanisms of tricalcium aluminate (C<sub>3</sub>A). The results uncover distinct dissociation pathways of calcium and aluminate ions. Specifically, Ca ions follow a ligand-exchange mechanism, preferentially transitioning to an unsaturated coordination state before bonding with water molecules. Conversely, Al ions first coordinate with water molecules to reach a supersaturated coordination state, which promotes the opening of six-membered rings and the cleavage of Al ions. This work elucidates the thermodynamics of C<sub>3</sub>A dissolution, deepening the understanding of mineral-water interfacial reactions, and provides an efficient, accurate approach for probing complex reaction pathways.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108124"},"PeriodicalIF":13.1,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145813726","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}
Pub Date : 2025-12-22DOI: 10.1016/j.cemconres.2025.108117
Huaming Liang , Hanlin Zou , Huan Wang , Zhendi Wang , Chunsheng Zhou
To quantify the correlation between dynamic drying shrinkage and pore-scale water removal kinetics, the pore-scale water allocation and dynamic shrinkage of white cement pastes upon drying at 75%, 43%, and 11% RHs were monitored and analyzed. Experimental results show a bilinear dependence of dynamic shrinkage on the removals of interlayer and gel water within CSH gel irrespective of RHs. CSH gel behaves like flexible hydrous sponges skewered by a stiff skeleton. Although CSH sponges lose water and contract remarkably upon drying, the spatial constraint of skeleton limits the deformation of pastes. Consequently, only 0.72% to 4.23% of interlayer and gel water losses are translated into measurable shrinkage. The removal of gel water contributes to shrinkage more than that of interlayer water due to the larger size of gel pores, though both their contributions decrease with declining RH and become similar. Mitigating shrinkage necessitates reducing CSH contraction and enhancing skeleton stiffness.
{"title":"Quantitative dependence of dynamic drying shrinkage of white cement pastes on pore-scale water removal kinetics","authors":"Huaming Liang , Hanlin Zou , Huan Wang , Zhendi Wang , Chunsheng Zhou","doi":"10.1016/j.cemconres.2025.108117","DOIUrl":"10.1016/j.cemconres.2025.108117","url":null,"abstract":"<div><div>To quantify the correlation between dynamic drying shrinkage and pore-scale water removal kinetics, the pore-scale water allocation and dynamic shrinkage of white cement pastes upon drying at 75%, 43%, and 11% RHs were monitored and analyzed. Experimental results show a bilinear dependence of dynamic shrinkage on the removals of interlayer and gel water within C<img>S<img>H gel irrespective of RHs. C<img>S<img>H gel behaves like flexible hydrous sponges skewered by a stiff skeleton. Although C<img>S<img>H sponges lose water and contract remarkably upon drying, the spatial constraint of skeleton limits the deformation of pastes. Consequently, only 0.72% to 4.23% of interlayer and gel water losses are translated into measurable shrinkage. The removal of gel water contributes to shrinkage more than that of interlayer water due to the larger size of gel pores, though both their contributions decrease with declining RH and become similar. Mitigating shrinkage necessitates reducing C<img>S<img>H contraction and enhancing skeleton stiffness.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108117"},"PeriodicalIF":13.1,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145812862","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}
Pub Date : 2025-12-22DOI: 10.1016/j.cemconres.2025.108119
Lang Pang , Jianwei Sun , John L. Provis , Barbara Lothenbach , Bin Ma , Dengquan Wang
The disposal of electrolytic manganese residue (EMR) is a critical challenge. This study introduces an EMR-blast furnace slag-Ca(OH)2 cementitious system (EGCH), utilizing the gypsum in EMR to activate the slag to form a product resembling a supersulfated cement. With up to 40 % EMR incorporation, it achieves compressive strengths of 16.8 MPa at 3 d and 33.2 MPa at 28 days. The primary reaction products are AFt, C-A-S-H and hydrotalcite. A thermodynamic simulation-assisted iterative calculation was developed and validated by pore solution analysis, to accurately quantify phase evolution. EMR content significantly influences the reaction and results in distinct exothermic profiles. The optimal 40 % EMR content results in the densest microstructure due to the balanced formation of AFt and C-A-S-H. Mn is immobilized in EGCH with two barriers to its leaching and cannot leach out until the pH drops below 7. This binder offers a practical solution for the utilization of EMR.
电解锰渣（EMR）的处理是一个严峻的挑战。本研究介绍了EMR-高炉矿渣- ca (OH)2胶凝体系（EGCH），利用EMR中的石膏活化矿渣，形成类似超硫酸盐水泥的产品。EMR掺入量高达40%，3d抗压强度为16.8 MPa， 28天抗压强度为33.2 MPa。主要反应产物为AFt、C-A-S-H和水滑石。建立了一种热力学模拟辅助迭代计算方法，并通过孔隙溶液分析验证了该方法的准确性。EMR含量显著影响反应并导致不同的放热曲线。最佳EMR含量为40%时，由于AFt和C-A-S-H的形成平衡，导致微观结构最致密。Mn被固定在EGCH中，有两种阻碍其浸出的障碍，直到pH降至7以下才会浸出。这种粘合剂为电子病历的利用提供了一种实用的解决方案。
{"title":"Thermodynamic simulation-assisted design of the electrolytic manganese residue-slag-Ca(OH)2 cementitious system: Reaction and Mn immobilization","authors":"Lang Pang , Jianwei Sun , John L. Provis , Barbara Lothenbach , Bin Ma , Dengquan Wang","doi":"10.1016/j.cemconres.2025.108119","DOIUrl":"10.1016/j.cemconres.2025.108119","url":null,"abstract":"<div><div>The disposal of electrolytic manganese residue (EMR) is a critical challenge. This study introduces an EMR-blast furnace slag-Ca(OH)<sub>2</sub> cementitious system (EG<sup>CH</sup>), utilizing the gypsum in EMR to activate the slag to form a product resembling a supersulfated cement. With up to 40 % EMR incorporation, it achieves compressive strengths of 16.8 MPa at 3 d and 33.2 MPa at 28 days. The primary reaction products are AFt, C-A-S-H and hydrotalcite. A thermodynamic simulation-assisted iterative calculation was developed and validated by pore solution analysis, to accurately quantify phase evolution. EMR content significantly influences the reaction and results in distinct exothermic profiles. The optimal 40 % EMR content results in the densest microstructure due to the balanced formation of AFt and C-A-S-H. Mn is immobilized in EG<sup>CH</sup> with two barriers to its leaching and cannot leach out until the pH drops below 7. This binder offers a practical solution for the utilization of EMR.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108119"},"PeriodicalIF":13.1,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145812864","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}
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