Pub Date : 2026-03-01Epub 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":"2026-03-01","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}
Pub Date : 2026-03-01Epub Date: 2025-12-20DOI: 10.1016/j.cemconres.2025.108123
Tulio Honorio , Walter Batista Bonfim , Oswaldo Cascudo
The impedance and complex electrical conductivity of C-S-H have not been directly measured, even though electromagnetic measurements are a key non-destructive technique for probing cement systems. Here, we evaluate the frequency-dependent electrical conductivity of C-S-H using molecular dynamics simulations for the first time. The effect of nanopore size is assessed for pores spanning the interlayer to the gel range, showing that interlayer conductivity is governed by subdiffusive ion dynamics while Fickean dynamics drives gel pores behavior. Ionic self-correlations dominate the conductivity, while water–ion and solid–ion contributions are smaller but non-negligible. By combining molecular dynamics with mean-field homogenization, we obtain gel-scale estimates consistent with available data (i.e., with ratio between gel conductivity and pore solution conductivity on the order of 1/100). As with other transport properties, accounting for anisotropy and associated dimensionality loss is critical for understanding electrical conductivity bottom-up. Our results provide direct evaluation of the frequency-dependent conductivity of C-S-H, offering valuable input for multiscale modeling and for interpreting electromagnetic measurements of cementitious materials.
{"title":"Impedance and electrical conductivity of C-S-H","authors":"Tulio Honorio , Walter Batista Bonfim , Oswaldo Cascudo","doi":"10.1016/j.cemconres.2025.108123","DOIUrl":"10.1016/j.cemconres.2025.108123","url":null,"abstract":"<div><div>The impedance and complex electrical conductivity of C-S-H have not been directly measured, even though electromagnetic measurements are a key non-destructive technique for probing cement systems. Here, we evaluate the frequency-dependent electrical conductivity of C-S-H using molecular dynamics simulations for the first time. The effect of nanopore size is assessed for pores spanning the interlayer to the gel range, showing that interlayer conductivity is governed by subdiffusive ion dynamics while Fickean dynamics drives gel pores behavior. Ionic self-correlations dominate the conductivity, while water–ion and solid–ion contributions are smaller but non-negligible. By combining molecular dynamics with mean-field homogenization, we obtain gel-scale estimates consistent with available data (i.e., with ratio between gel conductivity and pore solution conductivity on the order of 1/100). As with other transport properties, accounting for anisotropy and associated dimensionality loss is critical for understanding electrical conductivity bottom-up. Our results provide direct evaluation of the frequency-dependent conductivity of C-S-H, offering valuable input for multiscale modeling and for interpreting electromagnetic measurements of cementitious materials.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108123"},"PeriodicalIF":13.1,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145785097","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}
Despite their global abundance, heterogenous clays are often excluded from SCM applications, due to their limited pozzolanicity. This study investigates hydration evolution, particularly aluminum uptake pathways, in statistically designed cement blends incorporating thermo-mechanochemically activated low-kaolinite clays.
Despite kaolinite contents below 40%, a 30% binary blend achieved 110% and 125% of OPC strength at 7 and 56 days, respectively, while reducing total porosity by 42% at 56 days. 29Si NMR indicated an increase in silicate chain length in C-(A)-S-H, correlating with pore structure refinement and strength gain in 56 days of hydration. 27Al NMR revealed a preferential incorporation of aluminum into C-(A)-S-H rather than AFm phases. This behavior is attributed to the lower alumina availability in the system compared to LC3 blends, suggesting that in such environments, C-(A)-S-H becomes the dominant host phase for aluminum. This incorporation pathway reduces the Al availability for carbonate-AFm formation, limiting the synergy typically observed in LC3 systems with added limestone.
尽管非均质粘土在全球范围内丰富，但由于其有限的火山喷发性，它们通常被排除在SCM应用之外。本研究调查了统计设计的水泥混合物中水化演化，特别是铝的吸收途径，这些水泥混合物含有热机械化学活化的低高岭石粘土。尽管高岭石含量低于40%，但30%的二元共混物在第7天和第56天分别达到了OPC强度的110%和125%，同时在第56天将总孔隙度降低了42%。29Si核磁共振表明，C-(A)- s - h中的硅酸盐链长增加，这与水化56 d后孔隙结构的细化和强度的增加有关。27Al核磁共振显示铝优先掺入C-(a)- s - h相，而不是AFm相。这种行为归因于与LC3混合物相比，体系中氧化铝的可用性较低，这表明在这种环境下，C-(A)- s - h成为铝的主要宿主相。这种掺入途径降低了Al对碳酸盐- afm形成的可用性，限制了在添加石灰石的LC3体系中通常观察到的协同作用。
{"title":"Evolution of hydration in cement blends with incorporation of activated low-kaolinite clays: Insights into the preferred aluminum uptake by C-(A)-S-H","authors":"Amrita Hazarika , Liming Huang , Joao Figueira , Arezou Babaahmadi","doi":"10.1016/j.cemconres.2025.108086","DOIUrl":"10.1016/j.cemconres.2025.108086","url":null,"abstract":"<div><div>Despite their global abundance, heterogenous clays are often excluded from SCM applications, due to their limited pozzolanicity. This study investigates hydration evolution, particularly aluminum uptake pathways, in statistically designed cement blends incorporating thermo-mechanochemically activated low-kaolinite clays.</div><div>Despite kaolinite contents below 40%, a 30% binary blend achieved 110% and 125% of OPC strength at 7 and 56 days, respectively, while reducing total porosity by 42% at 56 days. <sup>29</sup>Si NMR indicated an increase in silicate chain length in C-(A)-S-H, correlating with pore structure refinement and strength gain in 56 days of hydration. <sup>27</sup>Al NMR revealed a preferential incorporation of aluminum into C-(A)-S-H rather than AFm phases. This behavior is attributed to the lower alumina availability in the system compared to LC3 blends, suggesting that in such environments, C-(A)-S-H becomes the dominant host phase for aluminum. This incorporation pathway reduces the Al availability for carbonate-AFm formation, limiting the synergy typically observed in LC3 systems with added limestone.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108086"},"PeriodicalIF":13.1,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731815","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 : 2026-03-01Epub 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":"2026-03-01","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 : 2026-02-01Epub Date: 2025-10-27DOI: 10.1016/j.cemconres.2025.108065
Lupesh Dudi, Shashank Bishnoi
Experiments were performed to study the corrosion kinetics of steel in carbonated Portland cement (PC) and four low-clinker binder (clinker replaced with fly-ash, slag, and calcined clay) mortars equilibrated at various relative humidity conditions. The results show that moisture content is the primary factor controlling the corrosion kinetics across all binder compositions, while pore structure connectivity and pore solution composition in carbonated binders are additional factors contributing to the higher corrosion rate observed in the low-clinker binders. In comparison to the PC, low-clinker binders have a higher and ratios (due to lower hydroxide ion concentration and release of chlorides and sulfates on carbonation), along with greater porosity and pore connectivity due to coarsening of pore structure after carbonation. Furthermore, the mechanism of corrosion rate-resistivity linear relationship in different carbonated binder compositions is explained based on corrosion rate per unit moisture content, pore solution compositions, and microstructure parameters.
{"title":"Moisture content as controlling mechanism behind corrosion rate of steel in carbonated low-clinker binders","authors":"Lupesh Dudi, Shashank Bishnoi","doi":"10.1016/j.cemconres.2025.108065","DOIUrl":"10.1016/j.cemconres.2025.108065","url":null,"abstract":"<div><div>Experiments were performed to study the corrosion kinetics of steel in carbonated Portland cement (PC) and four low-clinker binder (clinker replaced with fly-ash, slag, and calcined clay) mortars equilibrated at various relative humidity conditions. The results show that moisture content is the primary factor controlling the corrosion kinetics across all binder compositions, while pore structure connectivity and pore solution composition in carbonated binders are additional factors contributing to the higher corrosion rate observed in the low-clinker binders. In comparison to the PC, low-clinker binders have a higher <span><math><mfenced><mrow><mi>C</mi><msup><mi>l</mi><mo>−</mo></msup></mrow></mfenced><mo>/</mo><mfenced><mrow><mi>O</mi><msup><mi>H</mi><mo>−</mo></msup></mrow></mfenced></math></span> and <span><math><mfenced><mrow><mi>S</mi><msubsup><mi>O</mi><mn>4</mn><mrow><mn>2</mn><mo>−</mo></mrow></msubsup></mrow></mfenced><mo>/</mo><mfenced><mrow><mi>O</mi><msup><mi>H</mi><mo>−</mo></msup></mrow></mfenced></math></span> ratios (due to lower hydroxide ion concentration and release of chlorides and sulfates on carbonation), along with greater porosity and pore connectivity due to coarsening of pore structure after carbonation. Furthermore, the mechanism of corrosion rate-resistivity linear relationship in different carbonated binder compositions is explained based on corrosion rate per unit moisture content, pore solution compositions, and microstructure parameters.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108065"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145383466","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}
Introducing metakaolin and sodium water glass (silicate modulus – 2.8, density – 1100...1250 kg/m3) to ordinary portland cement (OPC) caused fundamental changes to the hydration products, forming ones from Na₂O-CaO-SiO₂-Al₂O₃-H₂O system and enhancing heat resistance. The setting times of metakaolin-containing alkali-activated portland cement were rather short. The increased heat resistance of this cement compared to OPC was shown, which is due to no rehydration of CaO, formed during the dehydration of Ca(OH)2, and recrystallization of zeolite-like phase of hydronepheline Na2O·Al2O3·2SiO2·2H2O into nepheline Na2O·Al2O3·2SiO2 without structural destruction. The recrystallization of C-A-S-H phases during sintering into gehlenite 2CaO·Al2O3·SiO2 contributed to a higher structure fragmentation while its self-reinforcement. These processes resulted in an increase in residual strength to 58.6…122.1 %. The mortar based on the designed cement was characterized by compressive strength ≥30 MPa, residual strength ≥70 %, and thermal shrinkage ≤5 % at temperatures up to 1000 °C.
引进偏高岭土和水玻璃钠(硅酸盐模量- 2.8，密度- 1100…1250 kg/m3)转化为普通硅酸盐水泥（OPC），使水化产物发生根本性变化，形成Na₂- cao - sio₂-Al₂O₃-H₂O体系水化产物，提高了耐热性。偏高岭土碱活化硅酸盐水泥的凝结时间较短。与OPC相比，该水泥的耐热性有所提高，这是由于Ca(OH)2脱水过程中形成的CaO没有再水化，并且水辉石Na2O·Al2O3·2SiO2·2H2O的沸石样相重结晶为霞辉石Na2O·Al2O3·2SiO2而没有结构破坏。在烧结成2CaO·Al2O3·SiO2的过程中，C-A-S-H相的再结晶导致了较高的结构破碎和自增强。这些工艺使残余强度提高到58.6% ~ 122.1%。设计的水泥砂浆在高达1000℃的温度下，抗压强度≥30 MPa，残余强度≥70%，热收缩≤5%。
{"title":"Development of metakaolin-enhanced alkali-activated portland cement for high-temperature applications","authors":"Pavlo Kryvenko , Igor Rudenko , Oleksandr Konstantynovskyi , Vladyslav Onatii","doi":"10.1016/j.cemconres.2025.108088","DOIUrl":"10.1016/j.cemconres.2025.108088","url":null,"abstract":"<div><div>Introducing metakaolin and sodium water glass (silicate modulus – 2.8, density <em>–</em> 1100...1250 kg/m<sup>3</sup>) to ordinary portland cement (OPC) caused fundamental changes to the hydration products, forming ones from Na₂O-CaO-SiO₂-Al₂O₃-H₂O system and enhancing heat resistance. The setting times of metakaolin-containing alkali-activated portland cement were rather short. The increased heat resistance of this cement compared to OPC was shown, which is due to no rehydration of CaO, formed during the dehydration of Ca(OH)<sub>2</sub>, and recrystallization of zeolite-like phase of hydronepheline Na<sub>2</sub>O·Al<sub>2</sub>O<sub>3</sub>·2SiO<sub>2</sub>·2H<sub>2</sub>O into nepheline Na<sub>2</sub>O·Al<sub>2</sub>O<sub>3</sub>·2SiO<sub>2</sub> without structural destruction. The recrystallization of C-A-S-H phases during sintering into gehlenite 2CaO·Al<sub>2</sub>O<sub>3</sub>·SiO<sub>2</sub> contributed to a higher structure fragmentation while its self-reinforcement. These processes resulted in an increase in residual strength to 58.6…122.1 %. The mortar based on the designed cement was characterized by compressive strength ≥30 MPa, residual strength ≥70 %, and thermal shrinkage ≤5 % at temperatures up to 1000 °C.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108088"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145536224","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":"Dynamic dissection of a sustainable cement alternative: A multiscale exploration of alkali-activated slag dissolution mechanisms","authors":"Jiazhi Huang , Baomin Wang","doi":"10.1016/j.cemconres.2025.108074","DOIUrl":"10.1016/j.cemconres.2025.108074","url":null,"abstract":"<div><div>The cement industry, contributing 8 % of global CO₂ emissions primarily through Ordinary Portland Cement (OPC) production (∼0.8–1.0 t CO₂/t), urgently requires low-carbon alternatives. This study elucidates atomic-scale dissolution mechanisms in alkali-activated ground granulated blast furnace slag (AAS) via integrated experimental-computational analysis. First-principles simulations of 412-atom GGBS models reveal Ca<sup>2+</sup>/Mg<sup>2+</sup> leaching initiates through non-bridging oxygen bond cleavage (ICOHP = -0.18–0.58 eV), while Al<sup>3+</sup>/Si<sup>4+</sup> release follows oligomer-mediated pathways. Quantum mechanics/molecular mechanics (QM/MM) calculations quantify bond-breaking energy barriers (Al-O-Al: 5.26 < Si-O-Al: 15.51 < Si-O-Si: 38.93 kcal/mol), governed by frontier orbital energy gaps (ΔE = 1.53–2.03 eV). Reactive molecular dynamics (MD) simulations identify three dissolution stages: Na<sup>+</sup>-assisted ion leaching (0–1 ns, D = 3.40 × 10<sup>−7</sup> m<sup>2</sup>/s), Al-O/Si-O network depolymerization (1–7 ns), and Ca-mediated calcium aluminosilicate hydrate (C-A-S-H) nucleation (7–30 ns). By modulating electronic structures to target these mechanisms, we achieve a 63 % carbon reduction compared to OPC. These findings establish design principles for next-generation GGBS-based cementitious materials, enabling scalable, low-carbon construction solutions with performance parity to conventional cement.</div><div><strong>Synopsis</strong></div><div>By transforming waste materials into valuable resources and reducing carbon emissions, we are paving the way for a more sustainable future.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108074"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145404945","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 : 2026-02-01Epub Date: 2025-11-14DOI: 10.1016/j.cemconres.2025.108087
Jing Xie , Xuanhan Zhang , Xiang Hu , Zemei Wu , Caijun Shi
This study comprehensively investigates the mechanism by which temperature (5–40 °C) affects the air bubble behavior in belite-rich cement (BRC), comparing with portland cement (PC) system. Key factors, including surface tension, ionic strength, internal matrix temperature, viscosity, and cement particle-bubble/SDS interactions, were analyzed. Bubble generation efficiency in pore solution was enhanced with temperature due to reduced surface tension and increased ionic strength. Relational degree between initial bubble volume and ionic strength (0.8938) was higher than that with surface tension (0.7018) in pore solution. A “critical temperature” (CT) governed bubble drainage, coalescence, and Ostwald ripening. For BRC concrete, increasing temperature below CT of 26 °C enhanced bubble stability by strengthening viscosity and particle-bubble interactions, thereby lowering spacing factor. Above CT, excessive heat caused bubble expansion/rupture, increasing spacing factor. Notably, as indicated by its higher CT, BRC exhibited inferior low-temperature (≤12 °C) stability compared to PC but superior high-temperature stability.
{"title":"Insights into the temperature effect on air bubble behavior in belite-rich cement systems","authors":"Jing Xie , Xuanhan Zhang , Xiang Hu , Zemei Wu , Caijun Shi","doi":"10.1016/j.cemconres.2025.108087","DOIUrl":"10.1016/j.cemconres.2025.108087","url":null,"abstract":"<div><div>This study comprehensively investigates the mechanism by which temperature (5–40 °C) affects the air bubble behavior in belite-rich cement (BRC), comparing with portland cement (PC) system. Key factors, including surface tension, ionic strength, internal matrix temperature, viscosity, and cement particle-bubble/SDS interactions, were analyzed. Bubble generation efficiency in pore solution was enhanced with temperature due to reduced surface tension and increased ionic strength. Relational degree between initial bubble volume and ionic strength (0.8938) was higher than that with surface tension (0.7018) in pore solution. A “critical temperature” (CT) governed bubble drainage, coalescence, and Ostwald ripening. For BRC concrete, increasing temperature below CT of 26 °C enhanced bubble stability by strengthening viscosity and particle-bubble interactions, thereby lowering spacing factor. Above CT, excessive heat caused bubble expansion/rupture, increasing spacing factor. Notably, as indicated by its higher CT, BRC exhibited inferior low-temperature (≤12 °C) stability compared to PC but superior high-temperature stability.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108087"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145509624","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 : 2026-02-01Epub Date: 2025-11-30DOI: 10.1016/j.cemconres.2025.108100
Zihan Ma , Yi Jiang , Shunmin Xiao , Xiao Zhang , Qinglong Qin , Jiangshan Li , Peiliang Shen , Chi-Sun Poon
This study systematically investigates the enforced carbonation behavior of tricalcium aluminate (C3A) across a precisely controlled pH range of 5.8–12.5. The results indicate that C3A carbonation is thermodynamically spontaneous; its overall rate, reaction pathway, and phase assemblage are significantly influenced by solution pH. The accumulation rate of calcium carbonate (Cc) increases sharply below pH 11.0 and peaks at pH 9.5–10.0, where only 4.1 wt% of the initial C3A remains after 10 min of carbonation. Phase analysis reveals a distinct pH-dependent transition: CO32−-AFm dominates when pH > 11.0, whereas Cc is the primary product when pH < 11.0. Mechanistically, pH governs C3A carbonation via three coupled effects: (i) by modulating Al dissolution, it alters the aqueous Ca/Al ratio, thereby adjusting the relative supersaturation of Cc and CO32−-AFm; (ii) it determines the precipitation threshold of Al(OH)3, enabling dissolved Al(OH)4− to react with nascent Cc and form CO32−-AFm; and (iii) at pH < 6, an Al-rich amorphous film rapidly forms on the surface, effectively halting further carbonation. These findings enhance our understanding of aluminate carbonation mechanisms in cementitious systems and provide insights into tailoring pH to optimize CO2 uptake in cement.
{"title":"pH-Dependent carbonation behavior of tricalcium aluminate","authors":"Zihan Ma , Yi Jiang , Shunmin Xiao , Xiao Zhang , Qinglong Qin , Jiangshan Li , Peiliang Shen , Chi-Sun Poon","doi":"10.1016/j.cemconres.2025.108100","DOIUrl":"10.1016/j.cemconres.2025.108100","url":null,"abstract":"<div><div>This study systematically investigates the enforced carbonation behavior of tricalcium aluminate (C<sub>3</sub>A) across a precisely controlled pH range of 5.8–12.5. The results indicate that C<sub>3</sub>A carbonation is thermodynamically spontaneous; its overall rate, reaction pathway, and phase assemblage are significantly influenced by solution pH. The accumulation rate of calcium carbonate (Cc) increases sharply below pH 11.0 and peaks at pH 9.5–10.0, where only 4.1 wt% of the initial C<sub>3</sub>A remains after 10 min of carbonation. Phase analysis reveals a distinct pH-dependent transition: CO<sub>3</sub><sup>2−</sup>-AFm dominates when pH > 11.0, whereas Cc is the primary product when pH < 11.0. Mechanistically, pH governs C<sub>3</sub>A carbonation via three coupled effects: (i) by modulating Al dissolution, it alters the aqueous Ca/Al ratio, thereby adjusting the relative supersaturation of Cc and CO<sub>3</sub><sup>2−</sup>-AFm; (ii) it determines the precipitation threshold of Al(OH)<sub>3</sub>, enabling dissolved Al(OH)<sub>4</sub><sup>−</sup> to react with nascent Cc and form CO<sub>3</sub><sup>2−</sup>-AFm; and (iii) at pH < 6, an Al-rich amorphous film rapidly forms on the surface, effectively halting further carbonation. These findings enhance our understanding of aluminate carbonation mechanisms in cementitious systems and provide insights into tailoring pH to optimize CO<sub>2</sub> uptake in cement.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108100"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145619725","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 : 2026-02-01Epub Date: 2025-11-11DOI: 10.1016/j.cemconres.2025.108084
Liang-yu Tong , Qing-feng Liu , Elke Gruyaert , Natalia Mariel Alderete , Qing-xiang Xiong , Nele De Belie
Replacement of ordinary Portland cement (OPC) by blast-furnace slag (BFS) modifies the durability behaviour of concrete. Combined with the experimental tests, this study proposes a comprehensive framework for modelling carbonation in BFS concrete, integrating hydration, transport-reactive, and diffusivity predictive modules. The framework enables synchronized iterations between chemical reaction modelling and transport processes considering microstructural evolution over time. Each module is validated against prior experimental data, including the volume fraction of hydration products, trend-based diffusivities and carbonation depths. Compared with model that neglect microstructural evolution, this framework, which considers altered compositional profiles after hydration and dynamically adjusts transport properties in response to microstructural changes during carbonation, yields higher predictive accuracy. Results indicate that carbonation resistance in BFS concrete improves with extended curing durations due to more complete hydration and a denser microstructure. Conversely, higher BFS replacement levels reduce the concrete's CO₂ buffering capacity and increase gas diffusivity after carbonation, finally accelerating carbonation. Parametric analysis further identifies an optimal relative humidity range for BFS concrete at approximately 30 %–60 %, and rising CO₂ concentrations increase carbonation depth. This innovative approach not only improves the accuracy of carbonation predictions but also serves as a valuable tool for optimizing the durability and hence sustainability of BFS-based construction materials.
{"title":"Experimental and numerical study on carbonation of blast-furnace slag concrete considering the microstructural evolution","authors":"Liang-yu Tong , Qing-feng Liu , Elke Gruyaert , Natalia Mariel Alderete , Qing-xiang Xiong , Nele De Belie","doi":"10.1016/j.cemconres.2025.108084","DOIUrl":"10.1016/j.cemconres.2025.108084","url":null,"abstract":"<div><div>Replacement of ordinary Portland cement (OPC) by blast-furnace slag (BFS) modifies the durability behaviour of concrete. Combined with the experimental tests, this study proposes a comprehensive framework for modelling carbonation in BFS concrete, integrating hydration, transport-reactive, and diffusivity predictive modules. The framework enables synchronized iterations between chemical reaction modelling and transport processes considering microstructural evolution over time. Each module is validated against prior experimental data, including the volume fraction of hydration products, trend-based diffusivities and carbonation depths. Compared with model that neglect microstructural evolution, this framework, which considers altered compositional profiles after hydration and dynamically adjusts transport properties in response to microstructural changes during carbonation, yields higher predictive accuracy. Results indicate that carbonation resistance in BFS concrete improves with extended curing durations due to more complete hydration and a denser microstructure. Conversely, higher BFS replacement levels reduce the concrete's CO₂ buffering capacity and increase gas diffusivity after carbonation, finally accelerating carbonation. Parametric analysis further identifies an optimal relative humidity range for BFS concrete at approximately 30 %–60 %, and rising CO₂ concentrations increase carbonation depth. This innovative approach not only improves the accuracy of carbonation predictions but also serves as a valuable tool for optimizing the durability and hence sustainability of BFS-based construction materials.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108084"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145485705","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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