Pub Date : 2026-10-26DOI: 10.1016/j.cemconres.2026.108447
Shengqian Ruan, Jian-Xin Lu, Wenlin Tu, Chi Sun Poon
Whether alkali-activated fly ash/slag (AAFS) is intrinsically more resistant than ordinary Portland cement (OPC) under sulfuric acid attack remains debatable, as the degradation process is multidimensional and controlled by coupled transport, dissolution, and precipitation processes. This study systematically investigated the sulfuric acid resistance of AAFS (10–75 wt% ground granulated blast-furnace slag, i.e. GGBS) and OPC-based binders (neat OPC and mixtures with 50 wt% GGBS or 25 wt% fly ash) at pH 1.0–2.0. Degradation-front propagation, degraded-layer robustness, and H2S release potential were evaluated. The evolution of phase assemblage, silicate structure, microstructure, and chemical profiles was analyzed to elucidate the degradation mechanisms. The results show that GGBS-rich AAFS and OPC-based binders both showed markedly slower acid ingress than fly ash-rich AAFS, mainly attributed to their higher volumetric density of acid-neutralizing Ca-, Na-, and Mg-bearing sites and lower capillary porosity. However, OPC-based binders developed gypsum-rich degraded layers, which were mechanically weaker and readily removed by flushing or disturbance. In contrast, fly ash-rich AAFS retained the most coherent degraded layers because their N–A–S–H-dominated matrix was more resistant to leaching-induced collapse and gypsum-related cracking. Therefore, binder selection should be guided by whether acid resistance or degraded-layer integrity is more critical in applications. A mechanistically informed descriptor, termed the acid-fixation efficiency, was further proposed to relate degradation-front propagation to the balance between acid-consuming capacity and transport potential. This framework can be used to predict acid resistance and to guide durable binder selection and material design.
碱活化粉煤灰/矿渣（AAFS）是否在本质上比普通硅酸盐水泥（OPC）更耐硫酸侵蚀仍存在争议，因为其降解过程是多方面的，受耦合输移、溶解和沉淀过程的控制。本研究系统地研究了AAFS（10-75 wt%磨碎的粒状高炉渣，即GGBS）和OPC基粘结剂（纯OPC和与50 wt% GGBS或25 wt%粉煤灰的混合物）在pH 1.0-2.0下的耐硫酸性能。降解前传播、降解层鲁棒性和H2S释放电位进行了评估。分析了相组合、硅酸盐结构、微观结构和化学特征的演变，阐明了降解机理。结果表明，与富粉煤灰的AAFS相比，富含ggbs的AAFS和opc基粘结剂的入酸速度明显减慢，这主要是由于它们具有更高的酸中和Ca、Na和mg位点的体积密度和更低的毛管孔隙度。然而，opc基粘合剂形成了富含石膏的降解层，其机械强度较弱，容易通过冲洗或扰动去除。相比之下，富含粉煤灰的AAFS保留了最一致的降解层，因为它们的n - a - s - h主导的基质更能抵抗浸出引起的坍塌和石膏相关的开裂。因此，粘合剂的选择应以耐酸性或降解层的完整性在应用中更为关键为指导。研究人员进一步提出了一个机械信息描述符，称为固酸效率，将降解前沿传播与酸消耗能力和运输潜力之间的平衡联系起来。该框架可用于预测耐酸性，并指导耐用粘合剂的选择和材料设计。
{"title":"New insights into sulfuric acid resistance mechanisms of alkali-activated and Portland cement systems","authors":"Shengqian Ruan, Jian-Xin Lu, Wenlin Tu, Chi Sun Poon","doi":"10.1016/j.cemconres.2026.108447","DOIUrl":"https://doi.org/10.1016/j.cemconres.2026.108447","url":null,"abstract":"Whether alkali-activated fly ash/slag (AAFS) is intrinsically more resistant than ordinary Portland cement (OPC) under sulfuric acid attack remains debatable, as the degradation process is multidimensional and controlled by coupled transport, dissolution, and precipitation processes. This study systematically investigated the sulfuric acid resistance of AAFS (10–75 wt% ground granulated blast-furnace slag, i.e. GGBS) and OPC-based binders (neat OPC and mixtures with 50 wt% GGBS or 25 wt% fly ash) at pH 1.0–2.0. Degradation-front propagation, degraded-layer robustness, and H<ce:inf loc=\"post\">2</ce:inf>S release potential were evaluated. The evolution of phase assemblage, silicate structure, microstructure, and chemical profiles was analyzed to elucidate the degradation mechanisms. The results show that GGBS-rich AAFS and OPC-based binders both showed markedly slower acid ingress than fly ash-rich AAFS, mainly attributed to their higher volumetric density of acid-neutralizing Ca-, Na-, and Mg-bearing sites and lower capillary porosity. However, OPC-based binders developed gypsum-rich degraded layers, which were mechanically weaker and readily removed by flushing or disturbance. In contrast, fly ash-rich AAFS retained the most coherent degraded layers because their N–A–S–H-dominated matrix was more resistant to leaching-induced collapse and gypsum-related cracking. Therefore, binder selection should be guided by whether acid resistance or degraded-layer integrity is more critical in applications. A mechanistically informed descriptor, termed the acid-fixation efficiency, was further proposed to relate degradation-front propagation to the balance between acid-consuming capacity and transport potential. This framework can be used to predict acid resistance and to guide durable binder selection and material design.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"28 1","pages":""},"PeriodicalIF":11.4,"publicationDate":"2026-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149274788","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 : 2026-05-01Epub Date: 2026-02-11DOI: 10.1016/j.cemconres.2026.108160
Morteza Tayebi , Katrin Schollbach , J.C.O. Zepper , Stefan Melzer , H.J.H. Brouwers
DRI in EAFs will reduce the availability of blast-furnace slag, necessitating alternative SCMs. Five DRI–EAF slags (four engineered, and one industrial) were investigated, spanning CaO/SiO₂ ≈ 1.3 or 2.0, FeOx ≈25 or 40 wt%, and cooling (air-cooled vs water-granulated). At 25 wt% clinker replacement, hydration and performance were quantified by isothermal and R3 calorimetry, UPV, autogenous shrinkage, XRD/TGA, compressive strength, and leaching. Cooling history, through the control of the amorphous fraction, governed reactivity: water-granulated slags exhibited higher cumulative heat, accelerated set, and superior strength activity indices compared to air-cooled analogues. Basicity and FeOx exerted secondary effects: higher basicity accelerated hydration and reduced autogenous shrinkage, whereas elevated FeOx retarded reaction. All binders formed C–S–H, ettringite, and portlandite; hydrotalcite-like LDHs were detected only for the low-basicity, water-granulated slag. All mortars complied with Dutch leaching limits and met SCM strength benchmarks, evidencing the viability of engineered DRI–EAF slags as low-CO₂ cementitious binders.
{"title":"Effect of phase composition on the reactivity of DRI-EAF slags as SCM","authors":"Morteza Tayebi , Katrin Schollbach , J.C.O. Zepper , Stefan Melzer , H.J.H. Brouwers","doi":"10.1016/j.cemconres.2026.108160","DOIUrl":"10.1016/j.cemconres.2026.108160","url":null,"abstract":"<div><div>DRI in EAFs will reduce the availability of blast-furnace slag, necessitating alternative SCMs. Five DRI–EAF slags (four engineered, and one industrial) were investigated, spanning CaO/SiO₂ ≈ 1.3 or 2.0, FeOx ≈25 or 40 wt%, and cooling (air-cooled vs water-granulated). At 25 wt% clinker replacement, hydration and performance were quantified by isothermal and R<sup>3</sup> calorimetry, UPV, autogenous shrinkage, XRD/TGA, compressive strength, and leaching. Cooling history, through the control of the amorphous fraction, governed reactivity: water-granulated slags exhibited higher cumulative heat, accelerated set, and superior strength activity indices compared to air-cooled analogues. Basicity and FeOx exerted secondary effects: higher basicity accelerated hydration and reduced autogenous shrinkage, whereas elevated FeOx retarded reaction. All binders formed C–S–H, ettringite, and portlandite; hydrotalcite-like LDHs were detected only for the low-basicity, water-granulated slag. All mortars complied with Dutch leaching limits and met SCM strength benchmarks, evidencing the viability of engineered DRI–EAF slags as low-CO₂ cementitious binders.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"203 ","pages":"Article 108160"},"PeriodicalIF":13.1,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146152976","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 : 2026-05-01Epub Date: 2026-02-10DOI: 10.1016/j.cemconres.2026.108158
Song Xiang , Huanchun Cai , Prannoy Suraneni , Xu Chen
The rheology of fresh geopolymers is primarily governed by Si content and alkalinity, yet the underlying mechanism in Ca-free systems remains insufficiently understood. Metakaolin geopolymers with (0–1) Na2O:1Al2O3:(2–4) SiO2:14H2O were investigated through rheological, microstructural, and spectroscopic characterizations. Yield stress peaked at 2.4 mol SiO2 and 0.3 mol Na2O. At these maxima, flocculated networks showed diminished roundness (<0.25) and increased fractal dimension (~1.67), alongside maximal dissolved Al concentrations (0.11 and 0.06 mol/L), signifying gelation-driven structural complexity. As Si content and alkalinity further increased, FTIR–ICP analyses revealed that progressive enrichment of surface-adsorbed Si/Al drove condensation to its temporary limit, while precipitating low-polymerized sodium silicates. This precipitation attachment enhanced roundness, reduced fractal dimension, and thus pronouncedly decreased yield stress. In silicate-activated systems, continued Si enrichment generated unstable silica-rich layers, as declining yield stress gradually stabilized. Collectively, these findings establish a mechanistic framework that simultaneously links rheology to floc structures and interfacial chemistry.
{"title":"Understanding the rheology of non-calcium metakaolin geopolymers from chemical and floc-structural perspectives: Effects of silicate concentration and alkalinity","authors":"Song Xiang , Huanchun Cai , Prannoy Suraneni , Xu Chen","doi":"10.1016/j.cemconres.2026.108158","DOIUrl":"10.1016/j.cemconres.2026.108158","url":null,"abstract":"<div><div>The rheology of fresh geopolymers is primarily governed by Si content and alkalinity, yet the underlying mechanism in Ca-free systems remains insufficiently understood. Metakaolin geopolymers with (0–1) Na<sub>2</sub>O:1Al<sub>2</sub>O<sub>3</sub>:(2–4) SiO<sub>2</sub>:14H<sub>2</sub>O were investigated through rheological, microstructural, and spectroscopic characterizations. Yield stress peaked at 2.4 mol SiO<sub>2</sub> and 0.3 mol Na<sub>2</sub>O. At these maxima, flocculated networks showed diminished roundness (<0.25) and increased fractal dimension (~1.67), alongside maximal dissolved Al concentrations (0.11 and 0.06 mol/L), signifying gelation-driven structural complexity. As Si content and alkalinity further increased, FTIR–ICP analyses revealed that progressive enrichment of surface-adsorbed Si/Al drove condensation to its temporary limit, while precipitating low-polymerized sodium silicates. This precipitation attachment enhanced roundness, reduced fractal dimension, and thus pronouncedly decreased yield stress. In silicate-activated systems, continued Si enrichment generated unstable silica-rich layers, as declining yield stress gradually stabilized. Collectively, these findings establish a mechanistic framework that simultaneously links rheology to floc structures and interfacial chemistry.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"203 ","pages":"Article 108158"},"PeriodicalIF":13.1,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146152980","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 : 2026-05-01Epub Date: 2026-02-10DOI: 10.1016/j.cemconres.2026.108161
Qiusong Chen , Tianjiao Yu , Daolin Wang , Bin Liu , Yan Feng , Qinli Zhang , Yikai Liu
Calcium aluminate cement (CAC), characterized by superior properties and low-carbon emission, shows strong potential to replace traditional ordinary Portland cement (OPC) in in-situ phosphogypsum (PG) backfill. Although the microstructural characteristics and pollutant immobilization have been investigated, its hydration kinetics, microstructural evolution, and carbon reduction behavior remain insufficiently explored. This study aims to investigate the intrinsic links between hydration mechanisms and macroscopic properties. The flowability, setting behavior, strength development, hydration characteristics and carbon footprints of CAC-based and OPC-based backfill systems were systematically evaluated through experiments and thermodynamic simulations. The results show that PG alters the hydration of CAC, exerting a dual effect on its macroscopic properties. Thermodynamic simulations indicate sequential formation of amorphous Al (OH)3, ettringite and OH-hydrotalcite, with synergistic interactions enhance strength development. The comparison of both systems shows that differences in product types, formation conditions and interactions fundamentally govern their macroscopic variations.
{"title":"Comparative study on phosphogypsum-based cemented paste backfill prepared with ordinary Portland cement and calcium aluminate cement: Correlations among macroscopic properties, thermodynamic behavior and hydration mechanism","authors":"Qiusong Chen , Tianjiao Yu , Daolin Wang , Bin Liu , Yan Feng , Qinli Zhang , Yikai Liu","doi":"10.1016/j.cemconres.2026.108161","DOIUrl":"10.1016/j.cemconres.2026.108161","url":null,"abstract":"<div><div>Calcium aluminate cement (CAC), characterized by superior properties and low-carbon emission, shows strong potential to replace traditional ordinary Portland cement (OPC) in in-situ phosphogypsum (PG) backfill. Although the microstructural characteristics and pollutant immobilization have been investigated, its hydration kinetics, microstructural evolution, and carbon reduction behavior remain insufficiently explored. This study aims to investigate the intrinsic links between hydration mechanisms and macroscopic properties. The flowability, setting behavior, strength development, hydration characteristics and carbon footprints of CAC-based and OPC-based backfill systems were systematically evaluated through experiments and thermodynamic simulations. The results show that PG alters the hydration of CAC, exerting a dual effect on its macroscopic properties. Thermodynamic simulations indicate sequential formation of amorphous Al (OH)<sub>3</sub>, ettringite and OH-hydrotalcite, with synergistic interactions enhance strength development. The comparison of both systems shows that differences in product types, formation conditions and interactions fundamentally govern their macroscopic variations.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"203 ","pages":"Article 108161"},"PeriodicalIF":13.1,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146152985","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 : 2026-05-01Epub Date: 2026-02-07DOI: 10.1016/j.cemconres.2026.108149
Sirajuddin Moghul , Léa Köller , Astrid Sidos , Franco Zunino , Robert J. Flatt
In blended cements, superplasticizers may distribute unevenly between the different mineral components, a challenge compounded by the heterogeneity of supplementary cementitious materials (SCMs). While it is understood that this may impact both rheology and hydration kinetics, the topic has not yet been addressed either systematically or quantitatively. This study does this by developing a quantitative framework called Pore Solution Matching (PSM), which enables systematic characterization superplasticizer distribution in multicomponent binders, using limestone calcined clay cement (LC3) as a representative system. This is done by using a polycarboxylate ether (PCE) and a diphosphonate superplasticizers. Protocols are established to conduct adsorption studies on the individual components of LC3, clinker, calcined clay, and limestone, to obtain results that represent an early-age LC3 paste. Integrating such data into a surface-based mass balance model it is possible to reconstruct polymer distributions and surface coverages across the different phases in LC3. As revealed by isothermal calorimetry this has important implications on hydration kinetics. Specifically, it is shown that the retardation response of LC3 varies linearly with the surface coverage of OPC by either of the superplasticizer used.
Though demonstrated here for LC3, the methodology and insights presented are applicable to a broad class of SCM-rich binders, offering a generalizable strategy for admixture design in a broad range of cementitious systems, including but not limited to low carbon cements.
{"title":"Pore solution matching: A method to resolve superplasticizer distributions in blended cements","authors":"Sirajuddin Moghul , Léa Köller , Astrid Sidos , Franco Zunino , Robert J. Flatt","doi":"10.1016/j.cemconres.2026.108149","DOIUrl":"10.1016/j.cemconres.2026.108149","url":null,"abstract":"<div><div>In blended cements, superplasticizers may distribute unevenly between the different mineral components, a challenge compounded by the heterogeneity of supplementary cementitious materials (SCMs). While it is understood that this may impact both rheology and hydration kinetics, the topic has not yet been addressed either systematically or quantitatively. This study does this by developing a quantitative framework called Pore Solution Matching (PSM), which enables systematic characterization superplasticizer distribution in multicomponent binders, using limestone calcined clay cement (LC3) as a representative system. This is done by using a polycarboxylate ether (PCE) and a diphosphonate superplasticizers. Protocols are established to conduct adsorption studies on the individual components of LC3, clinker, calcined clay, and limestone, to obtain results that represent an early-age LC3 paste. Integrating such data into a surface-based mass balance model it is possible to reconstruct polymer distributions and surface coverages across the different phases in LC3. As revealed by isothermal calorimetry this has important implications on hydration kinetics. Specifically, it is shown that the retardation response of LC3 varies linearly with the surface coverage of OPC by either of the superplasticizer used.</div><div>Though demonstrated here for LC3, the methodology and insights presented are applicable to a broad class of SCM-rich binders, offering a generalizable strategy for admixture design in a broad range of cementitious systems, including but not limited to low carbon cements.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"203 ","pages":"Article 108149"},"PeriodicalIF":13.1,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134210","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 : 2026-05-01Epub Date: 2026-02-10DOI: 10.1016/j.cemconres.2026.108147
Xi Chen , Dhanendra Kumar , En-Hua Yang
An alternative approach to developing low-carbon concrete is through carbon mineralization in aggregates. This research focuses on carbon mineralized magnesium (Mg)-based manufactured aggregates. First, a low-carbon synthesis process for brucite [Mg(OH)2] and the incorporation of silica fume to enhance the strength and carbon sequestration capacity were investigated. The 25% (by weight) of silica fume improved the mechanical strength (~31 MPa) and carbon sequestration capacity (~26 wt%) of manufactured aggregates. The underlying chemical and microstructural characterizations showed that silica fume acts as an inert filler. Carbon emission assessments yielded a negative carbon footprint of 0.186 kg CO₂/kg of aggregates. The 50% volumetric replacement of natural fine aggregates with manufactured aggregates in 50 MPa concrete retained the compressive strength, while also achieving a 10% reduction in embodied carbon. In the case of 20 MPa mortar, 100% of natural fine aggregates could be replaced with Mg-based manufactured aggregates developed in his study.
开发低碳混凝土的另一种方法是通过骨料中的碳矿化。本研究的重点是碳矿化镁（Mg）基人造骨料。首先，研究了水镁石[Mg(OH)2]的低碳合成工艺，并研究了硅灰的掺入以提高水镁石的强度和固碳能力。25%（重量）的硅灰提高了合成集料的机械强度（~31 MPa）和固碳能力（~26 wt%）。基础化学和微观结构表征表明，硅灰作为一种惰性填料。碳排放评估得出的负碳足迹为0.186 kg CO₂/kg骨料。在50 MPa的混凝土中，用人造骨料代替50%的天然细骨料，保留了抗压强度，同时也实现了10%的碳减排。在20mpa砂浆条件下，研制的mg基人造骨料可替代100%的天然细骨料。
{"title":"Carbon-negative magnesium-based manufactured aggregates development for carbon negative cement-based materials","authors":"Xi Chen , Dhanendra Kumar , En-Hua Yang","doi":"10.1016/j.cemconres.2026.108147","DOIUrl":"10.1016/j.cemconres.2026.108147","url":null,"abstract":"<div><div>An alternative approach to developing low-carbon concrete is through carbon mineralization in aggregates. This research focuses on carbon mineralized magnesium (Mg)-based manufactured aggregates. First, a low-carbon synthesis process for brucite [Mg(OH)<sub>2</sub>] and the incorporation of silica fume to enhance the strength and carbon sequestration capacity were investigated. The 25% (by weight) of silica fume improved the mechanical strength (~31 MPa) and carbon sequestration capacity (~26 wt%) of manufactured aggregates. The underlying chemical and microstructural characterizations showed that silica fume acts as an inert filler. Carbon emission assessments yielded a negative carbon footprint of 0.186 kg CO₂/kg of aggregates. The 50% volumetric replacement of natural fine aggregates with manufactured aggregates in 50 MPa concrete retained the compressive strength, while also achieving a 10% reduction in embodied carbon. In the case of 20 MPa mortar, 100% of natural fine aggregates could be replaced with Mg-based manufactured aggregates developed in his study.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"203 ","pages":"Article 108147"},"PeriodicalIF":13.1,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146152984","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 : 2026-05-01Epub Date: 2026-02-12DOI: 10.1016/j.cemconres.2026.108172
Jihoon Lee , Franco Zunino , Juhyuk Moon
The use of limestone can mitigate the limited availability of supplementary cementitious materials while reducing the clinker factor, but it often decreases strength. This study demonstrates that ethanoldiisopropanolamine (EDIPA) enables an increase in strength of slag-limestone cement. EDIPA facilitated the aluminate reaction, enhancing the formation of monocarbonate and ettringite in limestone-containing binder. Meanwhile, additional aluminates were preferentially incorporated into C–A–S–H rather than AFm phases in limestone-free binder. EDIPA improved the slag reactivity, increasing C–A–S–H precipitation with a lower Ca/Si ratio and a higher Al/Si ratio. Although neither EDIPA nor limestone influenced early sulfate adsorption on C–A–S–H, they seem to cause its desorption, resulting in additional ettringite formation at later ages. Consequently, EDIPA did not improve the strength of the limestone-free binder, but the combined increase in hydration products by EDIPA and limestone refined the pore structure and enhanced the strength, exceeding that of limestone-free binder despite a 20% limestone replacement.
{"title":"An advanced understanding for synergistic effect of limestone and ethanol di-isopropanolamine on slag-limestone ternary cement","authors":"Jihoon Lee , Franco Zunino , Juhyuk Moon","doi":"10.1016/j.cemconres.2026.108172","DOIUrl":"10.1016/j.cemconres.2026.108172","url":null,"abstract":"<div><div>The use of limestone can mitigate the limited availability of supplementary cementitious materials while reducing the clinker factor, but it often decreases strength. This study demonstrates that ethanoldiisopropanolamine (EDIPA) enables an increase in strength of slag-limestone cement. EDIPA facilitated the aluminate reaction, enhancing the formation of monocarbonate and ettringite in limestone-containing binder. Meanwhile, additional aluminates were preferentially incorporated into C–A–S–H rather than AFm phases in limestone-free binder. EDIPA improved the slag reactivity, increasing C–A–S–H precipitation with a lower Ca/Si ratio and a higher Al/Si ratio. Although neither EDIPA nor limestone influenced early sulfate adsorption on C–A–S–H, they seem to cause its desorption, resulting in additional ettringite formation at later ages. Consequently, EDIPA did not improve the strength of the limestone-free binder, but the combined increase in hydration products by EDIPA and limestone refined the pore structure and enhanced the strength, exceeding that of limestone-free binder despite a 20% limestone replacement.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"203 ","pages":"Article 108172"},"PeriodicalIF":13.1,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146160167","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 : 2026-05-01Epub Date: 2026-02-05DOI: 10.1016/j.cemconres.2026.108159
Qiaomu Zheng , En-Hua Yang , Yanqun Xu , Chen Li , Xinping Zhu , Zuhua Zhang , Zhengwu Jiang
By incorporating characteristic expansive agents, the crack self-healing capability of UHPFRC under aqueous carbonation is enhanced. Synergistic use of sulfur (ye'elimite-based, S-EA)- and magnesium (periclase-based, M-EA)-rich expansive agents reduces the capillary pore content/size through crystalline filling while increasing the gel pore volume by hydration promotion. Such a dual influence balances the overall chemical stability and the surface ion exchange capacity of UHPFRC. Post-cracking, slower periclase hydration from M-EA sustains the alkalinity of crack solution, thus stimulating secondary hydration and subsequent self-healing. S-EA-derived ettringite improves the spatial uniformity of self-healing products by templating the oriented carbonate nucleation during the early carbonation, whereas M-EA-derived brucite promotes the crack closure via prolonging the crack solution supersaturation and facilitating the calcite-aragonite intergrowth. During the later carbonation, Mg-calcite contributes to enhanced nanomechanical properties and modulated failure modes of self-healing products through localized lattice stress fields. Aragonite further reconstructs a more integrated self-healing phase-quartz aggregate interface through the reduction of lattice mismatches. These two mechanisms collectively reinforce the mechanical property restoration of UHPFRC.
{"title":"Aqueous carbonation-induced self-healing of UHPFRC: Role of sulfur/magnesium-rich expansive agents in crack closure and mechanical restoration","authors":"Qiaomu Zheng , En-Hua Yang , Yanqun Xu , Chen Li , Xinping Zhu , Zuhua Zhang , Zhengwu Jiang","doi":"10.1016/j.cemconres.2026.108159","DOIUrl":"10.1016/j.cemconres.2026.108159","url":null,"abstract":"<div><div>By incorporating characteristic expansive agents, the crack self-healing capability of UHPFRC under aqueous carbonation is enhanced. Synergistic use of sulfur (ye'elimite-based, S-EA)- and magnesium (periclase-based, M-EA)-rich expansive agents reduces the capillary pore content/size through crystalline filling while increasing the gel pore volume by hydration promotion. Such a dual influence balances the overall chemical stability and the surface ion exchange capacity of UHPFRC. Post-cracking, slower periclase hydration from M-EA sustains the alkalinity of crack solution, thus stimulating secondary hydration and subsequent self-healing. S-EA-derived ettringite improves the spatial uniformity of self-healing products by templating the oriented carbonate nucleation during the early carbonation, whereas M-EA-derived brucite promotes the crack closure via prolonging the crack solution supersaturation and facilitating the calcite-aragonite intergrowth. During the later carbonation, Mg-calcite contributes to enhanced nanomechanical properties and modulated failure modes of self-healing products through localized lattice stress fields. Aragonite further reconstructs a more integrated self-healing phase-quartz aggregate interface through the reduction of lattice mismatches. These two mechanisms collectively reinforce the mechanical property restoration of UHPFRC.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"203 ","pages":"Article 108159"},"PeriodicalIF":13.1,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122633","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 : 2026-05-01Epub Date: 2026-02-05DOI: 10.1016/j.cemconres.2026.108146
Laura Caneda-Martínez , Hela Bessaies-Bey , Xiaohan Yu , Karen Mourda , Patrick Belin , Belén González-Fonteboa , Nicolas Roussel
The contribution of early hydration products is often neglected in rheological studies of cementitious systems, particularly with respect to the quantitative evaluation of their influence on particle packing. Ettringite, owing to its predominance as an early-age hydration product and its frequently elongated morphology, is the most relevant phase to consider in this context. This study investigates the factors controlling ettringite morphology in the absence of admixtures and evaluates their impact on packing behaviour. Ettringite was synthesised under controlled solution conditions and analysed via microscopic techniques to assess the effect of ion concentration on morphology. In addition, the packing properties of ettringite samples of different morphology were studied by applying controlled compressive stress through centrifugation experiments. Results show that ettringite morphology is defined by solution supersaturation with respect to ettringite and mechanical stress: reduced supersaturation (i.e. dilution of the system) favours the formation of longer, thinner crystals, while stress induces breaking, with the resulting aspect ratio of the crystals dictated by the magnitude of the applied stress. Ettringite crystals were found to exhibit poor packing properties compared to those of common building materials. Moreover, a clear correlation between aspect ratio and packing properties was identified, consistent with predictive models for elongated macroscopic particles. These findings have significant practical implications, as understanding and controlling ettringite morphology can provide an effective means to tune early-age rheology in cement-based materials. We finally suggest that these findings are specifically relevant for low-clinker content binders where supersaturation is expected to be lower than traditional binders.
{"title":"Chemical and mechanical origin of ettringite morphology and packing properties","authors":"Laura Caneda-Martínez , Hela Bessaies-Bey , Xiaohan Yu , Karen Mourda , Patrick Belin , Belén González-Fonteboa , Nicolas Roussel","doi":"10.1016/j.cemconres.2026.108146","DOIUrl":"10.1016/j.cemconres.2026.108146","url":null,"abstract":"<div><div>The contribution of early hydration products is often neglected in rheological studies of cementitious systems, particularly with respect to the quantitative evaluation of their influence on particle packing. Ettringite, owing to its predominance as an early-age hydration product and its frequently elongated morphology, is the most relevant phase to consider in this context. This study investigates the factors controlling ettringite morphology in the absence of admixtures and evaluates their impact on packing behaviour. Ettringite was synthesised under controlled solution conditions and analysed via microscopic techniques to assess the effect of ion concentration on morphology. In addition, the packing properties of ettringite samples of different morphology were studied by applying controlled compressive stress through centrifugation experiments. Results show that ettringite morphology is defined by solution supersaturation with respect to ettringite and mechanical stress: reduced supersaturation (i.e. dilution of the system) favours the formation of longer, thinner crystals, while stress induces breaking, with the resulting aspect ratio of the crystals dictated by the magnitude of the applied stress. Ettringite crystals were found to exhibit poor packing properties compared to those of common building materials. Moreover, a clear correlation between aspect ratio and packing properties was identified, consistent with predictive models for elongated macroscopic particles. These findings have significant practical implications, as understanding and controlling ettringite morphology can provide an effective means to tune early-age rheology in cement-based materials. We finally suggest that these findings are specifically relevant for low-clinker content binders where supersaturation is expected to be lower than traditional binders.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"203 ","pages":"Article 108146"},"PeriodicalIF":13.1,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122649","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 : 2026-05-01Epub Date: 2026-02-05DOI: 10.1016/j.cemconres.2026.108154
Gen Li, Xiong Qian, Yining Gao, Peiliang Shen, Yong Tao, Chi Sun Poon
Water adsorption and capillary condensation in cementitious mesopores govern early transport and hydration kinetics, yet how surface chemistry couples to pore wetting remains unclear. Using grand canonical Monte Carlo simulations, we quantify water uptake and condensation in slit-shaped dicalcium silicate mesopores with varying surface hydroxylation degree. We identify a Matthew effect in hydration, i.e., a positive-feedback process in which water accumulation promotes surface hydroxylation, which in turn strengthens solid-liquid interactions and accelerates further uptake. The enhanced water adsorption on hydroxylated surfaces arises from more interfacial hydrogen bonds and shorter bonding distances, increasing the orientational ordering and structuring of interfacial water. Therefore, more reactive minerals develop more hydroxylated surfaces that increase water uptake and promote further hydration, exacerbating interphase heterogeneity in the hydration degree of cement paste. These results clarify the preferential transport and accumulation of water in cement mesopores and provide explanations for long-term hydration degree disparities of clinker phases.
{"title":"The Matthew effect in cement hydration: Hydroxylation-driven wetting of C2S mesopores","authors":"Gen Li, Xiong Qian, Yining Gao, Peiliang Shen, Yong Tao, Chi Sun Poon","doi":"10.1016/j.cemconres.2026.108154","DOIUrl":"10.1016/j.cemconres.2026.108154","url":null,"abstract":"<div><div>Water adsorption and capillary condensation in cementitious mesopores govern early transport and hydration kinetics, yet how surface chemistry couples to pore wetting remains unclear. Using grand canonical Monte Carlo simulations, we quantify water uptake and condensation in slit-shaped dicalcium silicate mesopores with varying surface hydroxylation degree. We identify a Matthew effect in hydration, i.e., a positive-feedback process in which water accumulation promotes surface hydroxylation, which in turn strengthens solid-liquid interactions and accelerates further uptake. The enhanced water adsorption on hydroxylated surfaces arises from more interfacial hydrogen bonds and shorter bonding distances, increasing the orientational ordering and structuring of interfacial water. Therefore, more reactive minerals develop more hydroxylated surfaces that increase water uptake and promote further hydration, exacerbating interphase heterogeneity in the hydration degree of cement paste. These results clarify the preferential transport and accumulation of water in cement mesopores and provide explanations for long-term hydration degree disparities of clinker phases.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"203 ","pages":"Article 108154"},"PeriodicalIF":13.1,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146122650","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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