Pub Date : 2026-03-16DOI: 10.1016/j.cemconres.2026.108191
Franz Becker, Friedlinde Goetz-Neunhoeffer, Jürgen Neubauer
The hydration of C3S with anhydrite and hydratable alumina was studied with heat flow calorimetry, XRD, and pore solution analysis. Two mixtures that would form predominantly monosulfate or ettringite along with straetlingite as predicted by thermodynamic modeling were selected. Additionally, an Al-rich mixture was chosen to show the effect of an aluminum surplus on C3S reaction. The hydration of these mixtures was analyzed and compared with the predicted phase assemblages from thermodynamic modeling. The results revealed the rapid formation of high amounts of ettringite in all systems. Throughout the hydration, the high ettringite supersaturation in close proximity to its solubility curves resulted in pore solution compositions kinetically favoring ettringite precipitation within the first 24 h. Resultant ion concentrations inhibited the formation of monosulfate due to its undersaturation. Simultaneously, an amorphous C-A-S-H phase, thermodynamically similar to zeolite_P(Ca), is expected to form until its undersaturation can lead to the formation of straetlingite.
{"title":"Hydration of C3S in anhydrite and hydratable alumina mixtures: Insights into experimental and thermodynamic phase development","authors":"Franz Becker, Friedlinde Goetz-Neunhoeffer, Jürgen Neubauer","doi":"10.1016/j.cemconres.2026.108191","DOIUrl":"https://doi.org/10.1016/j.cemconres.2026.108191","url":null,"abstract":"The hydration of C<sub>3</sub>S with anhydrite and hydratable alumina was studied with heat flow calorimetry, XRD, and pore solution analysis. Two mixtures that would form predominantly monosulfate or ettringite along with straetlingite as predicted by thermodynamic modeling were selected. Additionally, an Al-rich mixture was chosen to show the effect of an aluminum surplus on C<sub>3</sub>S reaction. The hydration of these mixtures was analyzed and compared with the predicted phase assemblages from thermodynamic modeling. The results revealed the rapid formation of high amounts of ettringite in all systems. Throughout the hydration, the high ettringite supersaturation in close proximity to its solubility curves resulted in pore solution compositions kinetically favoring ettringite precipitation within the first 24 h. Resultant ion concentrations inhibited the formation of monosulfate due to its undersaturation. Simultaneously, an amorphous C-A-S-H phase, thermodynamically similar to zeolite_P(Ca), is expected to form until its undersaturation can lead to the formation of straetlingite.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"59 1","pages":""},"PeriodicalIF":11.4,"publicationDate":"2026-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147478969","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: 2025-12-02DOI: 10.1016/j.cemconres.2025.108098
Charlotte Dewitte , Mateusz Wyrzykowski , Ellina Bernard
MgO-based cements represent a promising, low-CO2 alternative to traditional Portland cement. In magnesium silicate cements, M-S-H is the main phase. Although the thermodynamic properties and hydration mechanisms of this phase have been investigated, studies on its mechanical behaviour remain limited. This study aimed to determine the factors influencing the micro-mechanical properties of the MgO-SiO2 pastes. Detailed chemical (X-ray diffraction, Thermogravimetric analysis, Energy-dispersive spectrometry analysis), microstructural (water porosity), and mechanical (indentation) analyses were conducted. The source of raw materials and the production protocol (mortar mixer, ball mill, pressing) influence the mineralogy of pastes and silicon distribution. Additives have a moderate impact on the mineralogy of pastes. Samples with the lowest porosity exhibit the highest elastic properties. Once the effect of porosity is accounted for, a higher brucite content correlates with increased elastic properties.
{"title":"Factors influencing the micro-mechanical properties of MgO-SiO2 pastes","authors":"Charlotte Dewitte , Mateusz Wyrzykowski , Ellina Bernard","doi":"10.1016/j.cemconres.2025.108098","DOIUrl":"10.1016/j.cemconres.2025.108098","url":null,"abstract":"<div><div>MgO-based cements represent a promising, low-CO<sub>2</sub> alternative to traditional Portland cement. In magnesium silicate cements, M-S-H is the main phase. Although the thermodynamic properties and hydration mechanisms of this phase have been investigated, studies on its mechanical behaviour remain limited. This study aimed to determine the factors influencing the micro-mechanical properties of the MgO-SiO<sub>2</sub> pastes. Detailed chemical (X-ray diffraction, Thermogravimetric analysis, Energy-dispersive spectrometry analysis), microstructural (water porosity), and mechanical (indentation) analyses were conducted. The source of raw materials and the production protocol (mortar mixer, ball mill, pressing) influence the mineralogy of pastes and silicon distribution. Additives have a moderate impact on the mineralogy of pastes. Samples with the lowest porosity exhibit the highest elastic properties. Once the effect of porosity is accounted for, a higher brucite content correlates with increased elastic properties.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108098"},"PeriodicalIF":13.1,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145645794","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: 2025-12-23DOI: 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":"2026-03-01","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 : 2026-03-01Epub 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":"2026-03-01","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 : 2026-03-01Epub Date: 2025-12-18DOI: 10.1016/j.cemconres.2025.108103
Jesus López-Salas, J. Ivan Escalante-García
The synergistic activation of a novel one-part volcanic pumice-PC hybrid binder with a Na₂SO₄-Al₂(SO₄)₃-Ca(OH)₂ (NŜ-AŜ-CH) ternary system was elucidated using a suite of advanced characterization techniques. The reaction proceeds via two distinct pathways: a rapid sulfatic pathway, where Al₂(SO₄)₃ promotes ettringite (AFt) formation for early strength, and a primary alkaline pathway, where the Na₂SO₄-Ca(OH)₂ synergy generates in-situ NaOH, driving VP dissolution and C-(N)-A-S-H formation. This resulted in a nearly threefold increase in 1-day strength, with optimized binders reaching over 70 MPa at 90 days. Long-term analysis reveals the “dual role” of AS, as its persistent AFt provides microstructural reinforcement. This leads to a “composite strength mechanism,” a key finding where high strength is achieved even in systems with a less polymerized silicate network (low Mean Chain Length). The NS-CH synergy, in contrast, is the primary driver for high polymerization, informing a new model for designing sustainable binders.
采用一系列先进的表征技术，研究了一种新型的单组分火山浮石- pc复合粘结剂与Na₂SO₄-Al₂（SO₄）₃-Ca（OH）₂（NŜ-AŜ-CH）三元体系的协同活化作用。反应通过两种不同的途径进行：快速硫酸途径，其中Al₂（SO₄）₃促进钙矾石（AFt）的形成以获得早期强度；初级碱性途径，其中Na₂SO₄- ca (OH) 2协同作用产生原位NaOH，驱动VP溶解和C-(N) a -s - h的形成。这使得1天的强度增加了近3倍，优化后的粘合剂在90天的强度超过70 MPa。长期分析揭示了AS的“双重作用”，因为其持久的AFt提供了微观结构的强化。这导致了“复合强度机制”，这是一个关键的发现，即使在具有较少聚合硅酸盐网络（低平均链长）的系统中也能实现高强度。相比之下，NS-CH协同作用是高聚合的主要驱动因素，为设计可持续粘合剂提供了新的模型。
{"title":"Synergistic sulfate-alkaline activation of one-part volcanic pumice–cement binders: Mechanisms and microstructural evolution","authors":"Jesus López-Salas, J. Ivan Escalante-García","doi":"10.1016/j.cemconres.2025.108103","DOIUrl":"10.1016/j.cemconres.2025.108103","url":null,"abstract":"<div><div>The synergistic activation of a novel one-part volcanic pumice-PC hybrid binder with a Na₂SO₄-Al₂(SO₄)₃-Ca(OH)₂ (NŜ-AŜ-CH) ternary system was elucidated using a suite of advanced characterization techniques. The reaction proceeds via two distinct pathways: a rapid sulfatic pathway, where Al₂(SO₄)₃ promotes ettringite (AFt) formation for early strength, and a primary alkaline pathway, where the Na₂SO₄-Ca(OH)₂ synergy generates in-situ NaOH, driving VP dissolution and C-(N)-A-S-H formation. This resulted in a nearly threefold increase in 1-day strength, with optimized binders reaching over 70 MPa at 90 days. Long-term analysis reveals the “dual role” of AS, as its persistent AFt provides microstructural reinforcement. This leads to a “composite strength mechanism,” a key finding where high strength is achieved even in systems with a less polymerized silicate network (low Mean Chain Length). The NS-CH synergy, in contrast, is the primary driver for high polymerization, informing a new model for designing sustainable binders.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108103"},"PeriodicalIF":13.1,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145785131","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: 2025-12-17DOI: 10.1016/j.cemconres.2025.108102
José S. Andrade Neto , Ivo C. Carvalho , Henrique A. Santana , Paulo Matos , Ana Paula Kirchheim
This study applied a statistical mixture design to assess the influence of clinker composition and mineralogy on early hydration and strength. Twenty-one mixtures were prepared using six industrial clinkers with distinct mineralogical characteristics. Hydration was assessed using isothermal calorimetry, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Compressive strength was measured at 1 and 28 days. The results revealed that alkali content (Na2Oeq) was the most influential parameter controlling cumulative heat release up to 72 h. Interestingly, no clear correlation was observed between bulk phase content and early strength, emphasizing that mineralogical composition alone is not a reliable predictor of performance. These findings underscore the complexity of hydration mechanisms and highlight the importance of controlling clinker chemistry and mineralogy. Moreover, statistical mixture design proved an effective tool for exploring multivariate interactions governing hydration and strength development.
{"title":"The role of clinker mineralogy in cement properties: An analysis using statistical mixture design","authors":"José S. Andrade Neto , Ivo C. Carvalho , Henrique A. Santana , Paulo Matos , Ana Paula Kirchheim","doi":"10.1016/j.cemconres.2025.108102","DOIUrl":"10.1016/j.cemconres.2025.108102","url":null,"abstract":"<div><div>This study applied a statistical mixture design to assess the influence of clinker composition and mineralogy on early hydration and strength. Twenty-one mixtures were prepared using six industrial clinkers with distinct mineralogical characteristics. Hydration was assessed using isothermal calorimetry, X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Compressive strength was measured at 1 and 28 days. The results revealed that alkali content (Na<sub>2</sub>Oeq) was the most influential parameter controlling cumulative heat release up to 72 h. Interestingly, no clear correlation was observed between bulk phase content and early strength, emphasizing that mineralogical composition alone is not a reliable predictor of performance. These findings underscore the complexity of hydration mechanisms and highlight the importance of controlling clinker chemistry and mineralogy. Moreover, statistical mixture design proved an effective tool for exploring multivariate interactions governing hydration and strength development.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108102"},"PeriodicalIF":13.1,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797700","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: 2025-12-03DOI: 10.1016/j.cemconres.2025.108099
Qiaomu Zheng , En-Hua Yang , Chen Li , Qiang Ren , Hongen Zhang , Wenting Li , Sifan Zhang , Zhengwu Jiang
Enhancing the toughness gain of ultra-high performance fiber-reinforced concrete (UHPFRC) through fundamental unit (e.g., nanostructure) optimization remains a challenge. This work explores the multi-scale mechanical behaviors of UHPFRC under four-point flexural loads, incorporating silica fume (SF) and ultra-fine fly ash (UFFA) as the ultra-fine mineral additives. SF and UFFA promote the formation of C(A)SH with high Si/Ca and Al/Ca ratio, altering the structural characteristics of both cement matrix and fiber-matrix interface. At the nanoscale, SF enhances the C(A)SH modulus through higher cohesion force, while UFFA elevates its friction coefficient; although both additives decrease C(A)SH hardness by reduced intrinsic modulus, their synergism improves C(A)SH stiffness. At the micro/macroscale, the stiffness of cement matrix and modulus of fiber-matrix interface dominate the strain-hardening behavior before fiber debonding, whereas the stiffness and friction coefficient of interface control the strain-softening process during fiber pulling-out. These insights highlight the hierarchical pathway to toughness modulation in UHPFRC.
{"title":"Multi-scale mechanical behaviors of ultra-high performance fiber-reinforced concrete influenced by ultra-fine mineral additives: A hierarchical perspective on toughness gain modulation","authors":"Qiaomu Zheng , En-Hua Yang , Chen Li , Qiang Ren , Hongen Zhang , Wenting Li , Sifan Zhang , Zhengwu Jiang","doi":"10.1016/j.cemconres.2025.108099","DOIUrl":"10.1016/j.cemconres.2025.108099","url":null,"abstract":"<div><div>Enhancing the toughness gain of ultra-high performance fiber-reinforced concrete (UHPFRC) through fundamental unit (e.g., nanostructure) optimization remains a challenge. This work explores the multi-scale mechanical behaviors of UHPFRC under four-point flexural loads, incorporating silica fume (SF) and ultra-fine fly ash (UFFA) as the ultra-fine mineral additives. SF and UFFA promote the formation of C(<em>A</em>)SH with high Si/Ca and Al/Ca ratio, altering the structural characteristics of both cement matrix and fiber-matrix interface. At the nanoscale, SF enhances the C(<em>A</em>)SH modulus through higher cohesion force, while UFFA elevates its friction coefficient; although both additives decrease C(<em>A</em>)SH hardness by reduced intrinsic modulus, their synergism improves C(<em>A</em>)SH stiffness. At the micro/macroscale, the stiffness of cement matrix and modulus of fiber-matrix interface dominate the strain-hardening behavior before fiber debonding, whereas the stiffness and friction coefficient of interface control the strain-softening process during fiber pulling-out. These insights highlight the hierarchical pathway to toughness modulation in UHPFRC.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108099"},"PeriodicalIF":13.1,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145673801","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: 2025-12-16DOI: 10.1016/j.cemconres.2025.108118
Jiaze Wang , Hangjie Zhou , Yufeng Song , Chengzhuo Xie , Cise Unluer , Shaoqin Ruan
The reactivity of magnesia (MgO) is a critical determinant of the performance of magnesia-based cements. While conventional theory correlates MgO reactivity primarily with specific surface area (SSA), this study utilizes a multi-technique approach to reveal a more complex dependency governed by the interplay between pore structure and surface defect density. Through controlled synthesis of MgO from calcinating Mg(OH)2 at 400, 500, and 600 °C for 2 h, we demonstrate that the sample calcined at 500 °C (S5–2) exhibits the highest reactivity, despite possessing a lower SSA than the 400 °C counterpart. A multi-technique approach, combining TEM, in-situ XRD, BET, LF-NMR, XPS, PL, and ESR analyses, reveals that this enhanced reactivity is strongly correlated with a synergistic combination of a favorable mesoporous architecture (~10–100 nm), hypothesized to facilitate efficient water transport, and a maximized concentration of surface oxygen vacancies, which are believed to promote hydrolysis. This perspective supplements existing theory and provides guidance for designing magnesia cements with stable and reproducible performance, addressing one of the major challenges in this field.
{"title":"Revisiting MgO reactivity: The critical role of mesopores and surface defects of particles","authors":"Jiaze Wang , Hangjie Zhou , Yufeng Song , Chengzhuo Xie , Cise Unluer , Shaoqin Ruan","doi":"10.1016/j.cemconres.2025.108118","DOIUrl":"10.1016/j.cemconres.2025.108118","url":null,"abstract":"<div><div>The reactivity of magnesia (MgO) is a critical determinant of the performance of magnesia-based cements. While conventional theory correlates MgO reactivity primarily with specific surface area (SSA), this study utilizes a multi-technique approach to reveal a more complex dependency governed by the interplay between pore structure and surface defect density. Through controlled synthesis of MgO from calcinating Mg(OH)<sub>2</sub> at 400, 500, and 600 °C for 2 h, we demonstrate that the sample calcined at 500 °C (S5–2) exhibits the highest reactivity, despite possessing a lower SSA than the 400 °C counterpart. A multi-technique approach, combining TEM, in-situ XRD, BET, LF-NMR, XPS, PL, and ESR analyses, reveals that this enhanced reactivity is strongly correlated with a synergistic combination of a favorable mesoporous architecture (~10–100 nm), hypothesized to facilitate efficient water transport, and a maximized concentration of surface oxygen vacancies, which are believed to promote hydrolysis. This perspective supplements existing theory and provides guidance for designing magnesia cements with stable and reproducible performance, addressing one of the major challenges in this field.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"201 ","pages":"Article 108118"},"PeriodicalIF":13.1,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145797702","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: 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":"2026-03-01","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 : 2026-03-01Epub Date: 2025-12-09DOI: 10.1016/j.cemconres.2025.108101
Thomas Bernard , William Wilson
The chloride penetration rate in a cementitious system characterizes its ability to resist chloride-induced corrosion. Assessing this property involves determining a diffusion coefficient obtained from diffusion or migration tests, or from models. The evolution of penetration depth can be used to predict the durability of a cementitious system, as it follows a linear relationship with the square root of time, known as the square root law. However, given the many assumptions behind this law, it remains unclear when and how it can be used to predict future penetration depths. This study investigates the applicability of the law for seven binders and shows that it can be used to monitor the evolution of penetration depth before the stabilization of the properties of the specimen, except when glass powder is used. However, predicting future penetration depths is more accurate when both the microstructure and surface content are stable.
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