Pub 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":"2025-12-02","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 : 2025-12-01DOI: 10.1016/j.cemconres.2025.108094
Jiaxin Liao , Jian Liu , Haocheng Zhao , Xiangming Kong , Zhongzhou Xu , Puyu Zhou
Shotcrete often exhibits lower strength after several days despite its rapid setting, primarily because accelerators interfere with cement hydration and microstructure development. This study investigates the effects of two typical accelerators—aluminium sulphate (AS) and sodium aluminate (NA)—on setting behaviour and early strength of cementitious materials. Isothermal calorimetry, XRD, and TGA were employed to characterize the hydration process, while low-field NMR (LF-NMR) was used to monitor pore structure evolution. The results show that increasing dosages of AS and NA proportionally reduces setting time while increasing the 12-h strength of cement mortars. At equivalent aluminium contents, NA is more effective than AS in setting acceleration. Within 3 days of curing, the mortars with AS exhibit consistently higher strength than the reference, whereas those with NA demonstrate the opposite comparison, although both AS and NA visibly accelerate C₃S hydration. AS promotes ettringite formation, while NA favours AFm and calcium aluminate hydrates. Based on the influence of porosity on strength, the pores measured by LF-NMR in hardened cement pastes (HCPs) are categorized as harmless pores including interlayer and gel pores of C–S–H, and harmful pores including interhydrate and capillary pores. AS decreases both total and harmful porosity in HCPs while increasing harmless porosity. In contrast, NA shows opposite trend, with total porosity remaining approximately unchanged. A semi-empirical model correlating mortar strength with harmless and harmful porosity is proposed to account for the effects of pore filling, interparticle binding of hydration products, and pore size distribution of HCPs on strength development.
{"title":"Quantitative correlation of cement hydration, pore structure evolution and strength development of cement pastes with accelerators","authors":"Jiaxin Liao , Jian Liu , Haocheng Zhao , Xiangming Kong , Zhongzhou Xu , Puyu Zhou","doi":"10.1016/j.cemconres.2025.108094","DOIUrl":"10.1016/j.cemconres.2025.108094","url":null,"abstract":"<div><div>Shotcrete often exhibits lower strength after several days despite its rapid setting, primarily because accelerators interfere with cement hydration and microstructure development. This study investigates the effects of two typical accelerators—aluminium sulphate (AS) and sodium aluminate (NA)—on setting behaviour and early strength of cementitious materials. Isothermal calorimetry, XRD, and TGA were employed to characterize the hydration process, while low-field NMR (LF-NMR) was used to monitor pore structure evolution. The results show that increasing dosages of AS and NA proportionally reduces setting time while increasing the 12-h strength of cement mortars. At equivalent aluminium contents, NA is more effective than AS in setting acceleration. Within 3 days of curing, the mortars with AS exhibit consistently higher strength than the reference, whereas those with NA demonstrate the opposite comparison, although both AS and NA visibly accelerate C₃S hydration. AS promotes ettringite formation, while NA favours AFm and calcium aluminate hydrates. Based on the influence of porosity on strength, the pores measured by LF-NMR in hardened cement pastes (HCPs) are categorized as harmless pores including interlayer and gel pores of C–S–H, and harmful pores including interhydrate and capillary pores. AS decreases both total and harmful porosity in HCPs while increasing harmless porosity. In contrast, NA shows opposite trend, with total porosity remaining approximately unchanged. A semi-empirical model correlating mortar strength with harmless and harmful porosity is proposed to account for the effects of pore filling, interparticle binding of hydration products, and pore size distribution of HCPs on strength development.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108094"},"PeriodicalIF":13.1,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145645310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-30DOI: 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":"2025-11-30","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 : 2025-11-29DOI: 10.1016/j.cemconres.2025.108095
Huawei Liu , Yaxin Tao , Chao Zhu , Chao Liu , Yifei Wang , Jiao Yun , Yukun Zhang
3D printed concrete exhibits significant durability issues under freeze–thaw (F–T) conditions due to its unique pore structure, restricting its widespread application in cold regions. In this study, the frost resistance of 3D printed recycled aggregate concrete (3DPRAC) was systematically evaluated at different recycled coarse aggregate (RCA) replacement ratios (0 %, 50 %, and 100 %), and the underlying damage mechanisms induced by F–T cycles were elucidated. Results indicated that the frost resistance of 3DPRAC was notably inferior to cast concrete and further deteriorated nonlinearly with increasing RCA replacement ratios. Ellipsoidal pores within 3DPRAC facilitated ice crystal formation, accelerating crack initiation and propagation. Damage originated from the porous old mortar in RCA and dual interfacial transition zones, while ultimate failure was dominated by a multi-interface and pore structure defect system jointly formed by RCA and printed structure. This research provides theoretical insights for durability design of 3D printed concrete structures in cold-region applications.
{"title":"3D printed concrete with recycled coarse aggregate: Freeze–thaw resistance assessment and damage mechanisms","authors":"Huawei Liu , Yaxin Tao , Chao Zhu , Chao Liu , Yifei Wang , Jiao Yun , Yukun Zhang","doi":"10.1016/j.cemconres.2025.108095","DOIUrl":"10.1016/j.cemconres.2025.108095","url":null,"abstract":"<div><div>3D printed concrete exhibits significant durability issues under freeze–thaw (F–T) conditions due to its unique pore structure, restricting its widespread application in cold regions. In this study, the frost resistance of 3D printed recycled aggregate concrete (3DPRAC) was systematically evaluated at different recycled coarse aggregate (RCA) replacement ratios (0 %, 50 %, and 100 %), and the underlying damage mechanisms induced by F–T cycles were elucidated. Results indicated that the frost resistance of 3DPRAC was notably inferior to cast concrete and further deteriorated nonlinearly with increasing RCA replacement ratios. Ellipsoidal pores within 3DPRAC facilitated ice crystal formation, accelerating crack initiation and propagation. Damage originated from the porous old mortar in RCA and dual interfacial transition zones, while ultimate failure was dominated by a multi-interface and pore structure defect system jointly formed by RCA and printed structure. This research provides theoretical insights for durability design of 3D printed concrete structures in cold-region applications.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108095"},"PeriodicalIF":13.1,"publicationDate":"2025-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145613721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-27DOI: 10.1016/j.cemconres.2025.108096
Xiaobo Niu , Yogarajah Elakneswaran , Ryosuke Kikuchi , Ang Li , Sivasubramaniam Seralathan , Yoshihisa Hiraki , Junya Sato , Takeshi Osugi , Takashi Kamiyama , Brant Walkley
The incorporation of boron (B) as a neutron absorber into metakaolin-based geopolymers for the remediation of radioactive debris following nuclear accidents has attracted considerable attention. In this study, boron carbide (B4C) was employed as a functional filler, while cetyltrimethylammonium bromide (CTAB) acted as both a dispersant and a stabiliser to enhance the neutron shielding properties of metakaolin-based geopolymers. Although the addition of B4C improved processability via a “roller-ball” effect and had no discernible impact on the geopolymerisation process, its weakly polar, negatively charged surface led to the formation of a loose, weak-shell interfacial transition zone (ITZ) between the filler and the matrix, thereby reducing mechanical strength and chemical stability. In contrast, CTAB self-assembled into an interdigitated monolayer on the B4C surface, reversing its surface charge to positive and promoting its uniform dispersion within the matrix. While CTAB slightly inhibited the dissolution of metakaolin, it preferentially interacted with B4C, thereby mitigating the adverse effects on the geopolymerisation process. Moreover, CTAB promoted gelation within the ITZ surrounding B4C, facilitating the development of a dense, potassium-deficient, yet electrostatically stabilised microstructure. This synergistic interaction enhanced interfacial bonding between the filler and the matrix, enabled efficient stress transfer, and significantly improved mechanical performance and chemical stability. Furthermore, the B4C–CTAB-modified geopolymers demonstrated enhanced neutron shielding performance. Overall, this work offers a promising approach for engineering high-performance, multifunctional geopolymer composites for nuclear and environmental applications.
{"title":"Tailoring neutron-shielding boron-metakaolin geopolymers with B4C filler: Surfactant-driven interfacial and microstructural control","authors":"Xiaobo Niu , Yogarajah Elakneswaran , Ryosuke Kikuchi , Ang Li , Sivasubramaniam Seralathan , Yoshihisa Hiraki , Junya Sato , Takeshi Osugi , Takashi Kamiyama , Brant Walkley","doi":"10.1016/j.cemconres.2025.108096","DOIUrl":"10.1016/j.cemconres.2025.108096","url":null,"abstract":"<div><div>The incorporation of boron (B) as a neutron absorber into metakaolin-based geopolymers for the remediation of radioactive debris following nuclear accidents has attracted considerable attention. In this study, boron carbide (B<sub>4</sub>C) was employed as a functional filler, while cetyltrimethylammonium bromide (CTAB) acted as both a dispersant and a stabiliser to enhance the neutron shielding properties of metakaolin-based geopolymers. Although the addition of B<sub>4</sub>C improved processability via a “roller-ball” effect and had no discernible impact on the geopolymerisation process, its weakly polar, negatively charged surface led to the formation of a loose, weak-shell interfacial transition zone (ITZ) between the filler and the matrix, thereby reducing mechanical strength and chemical stability. In contrast, CTAB self-assembled into an interdigitated monolayer on the B<sub>4</sub>C surface, reversing its surface charge to positive and promoting its uniform dispersion within the matrix. While CTAB slightly inhibited the dissolution of metakaolin, it preferentially interacted with B<sub>4</sub>C, thereby mitigating the adverse effects on the geopolymerisation process. Moreover, CTAB promoted gelation within the ITZ surrounding B<sub>4</sub>C, facilitating the development of a dense, potassium-deficient, yet electrostatically stabilised microstructure. This synergistic interaction enhanced interfacial bonding between the filler and the matrix, enabled efficient stress transfer, and significantly improved mechanical performance and chemical stability. Furthermore, the B<sub>4</sub>C–CTAB-modified geopolymers demonstrated enhanced neutron shielding performance. Overall, this work offers a promising approach for engineering high-performance, multifunctional geopolymer composites for nuclear and environmental applications.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108096"},"PeriodicalIF":13.1,"publicationDate":"2025-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145609236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-26DOI: 10.1016/j.cemconres.2025.108092
Barbara Lothenbach , Ellina Bernard , Zeyu Zhou , Alexander German , Paula Montserrat-Torres , Frank Winnefeld
MgO can be sourced from magnesium silicates or desalination brines with no direct CO2 emissions from the raw materials. This paper critically reviews available literature on magnesium carbonate cements prepared from MgO, water and magnesium carbonates such as nesquehonite or hydromagnesite. Such MgO - magnesium carbonate cements develop high early strength due to the formation of hydrous carbonate-containing brucite (HCB), which incorporates both carbonate and H2O into its structure. Hydrated magnesium carbonate cements have a high potential to bind additional CO2. In the presence of SiO2, magnesium silicate hydrates (M-S-H) also form, which exhibit a high resistance to carbonation. The Mg/Si ratio governs the phase assemblage, as silica can react with HCB to form M-S-H. Magnesium carbonate and silicate hydrate cements have a pH value ranging from 10 to 11, demonstrate a high resistance to leaching, while the corrosion rate of steel rebars is comparable to PC.
{"title":"Critical review of the properties of MgO - magnesium carbonate cements","authors":"Barbara Lothenbach , Ellina Bernard , Zeyu Zhou , Alexander German , Paula Montserrat-Torres , Frank Winnefeld","doi":"10.1016/j.cemconres.2025.108092","DOIUrl":"10.1016/j.cemconres.2025.108092","url":null,"abstract":"<div><div>MgO can be sourced from magnesium silicates or desalination brines with no direct CO<sub>2</sub> emissions from the raw materials. This paper critically reviews available literature on magnesium carbonate cements prepared from MgO, water and magnesium carbonates such as nesquehonite or hydromagnesite. Such MgO - magnesium carbonate cements develop high early strength due to the formation of hydrous carbonate-containing brucite (HCB), which incorporates both carbonate and H<sub>2</sub>O into its structure. Hydrated magnesium carbonate cements have a high potential to bind additional CO<sub>2</sub>. In the presence of SiO<sub>2</sub>, magnesium silicate hydrates (M-S-H) also form, which exhibit a high resistance to carbonation. The Mg/Si ratio governs the phase assemblage, as silica can react with HCB to form M-S-H. Magnesium carbonate and silicate hydrate cements have a pH value ranging from 10 to 11, demonstrate a high resistance to leaching, while the corrosion rate of steel rebars is comparable to PC.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108092"},"PeriodicalIF":13.1,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145598629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-26DOI: 10.1016/j.cemconres.2025.108089
Shengnan Sha, Sirajuddin Moghul, Robert J. Flatt
The timing of superplasticizer addition is known to impact both the yield stress and hydration kinetics of cementitious systems. Recent results demonstrate that these changes can be directly related to changes in the specific surface area of the cement paste. As this results from a change in hydrate morphology, in particular ettringite, two main reasons may explain yield stress changes in relation to addition time.
On the one hand, these may result from changes in adsorption. On the other hand, they may be due to changes in the maximum packing of the cement paste. To examine both scenarios, we have applied the YODEL, a Yield Stress mODEL that has been recognized as an effective model for predicting the yield stress of cement-based materials.
By doing this, we could evaluate the relative roles of changes in adsorption and of maximum packing in cement-limestone pastes. Results indicate that, in the range of yield stresses and volume fractions measurable in our experiments, changes in adsorption, rather than variations in maximum packing, are the primary difference between direct and delayed addition.
{"title":"New insights into the role of superplasticizer addition time on yield stress of cementitious materials","authors":"Shengnan Sha, Sirajuddin Moghul, Robert J. Flatt","doi":"10.1016/j.cemconres.2025.108089","DOIUrl":"10.1016/j.cemconres.2025.108089","url":null,"abstract":"<div><div>The timing of superplasticizer addition is known to impact both the yield stress and hydration kinetics of cementitious systems. Recent results demonstrate that these changes can be directly related to changes in the specific surface area of the cement paste. As this results from a change in hydrate morphology, in particular ettringite, two main reasons may explain yield stress changes in relation to addition time.</div><div>On the one hand, these may result from changes in adsorption. On the other hand, they may be due to changes in the maximum packing of the cement paste. To examine both scenarios, we have applied the YODEL, a Yield Stress mODEL that has been recognized as an effective model for predicting the yield stress of cement-based materials.</div><div>By doing this, we could evaluate the relative roles of changes in adsorption and of maximum packing in cement-limestone pastes. Results indicate that, in the range of yield stresses and volume fractions measurable in our experiments, changes in adsorption, rather than variations in maximum packing, are the primary difference between direct and delayed addition.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108089"},"PeriodicalIF":13.1,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145598619","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}
This study examines the microstructural evolution and changes in the properties of C–S–H in a cement paste hydrated at elevated temperatures ranging from 110 to 190 C. Using a simple slurry formulation composed only of Class G cement and water, the material’s evolution was quantitatively investigated through a multi-technique approach, including mechanical testing (UCT), microstructural analysis (MIP), and chemical characterization (TGA and XRD). The results reveal two key mechanisms driving the observed strength loss: (1) a significant increase in porosity and pore size over time, leading to microstructural coarsening, and (2) the formation of denser crystalline phases with higher C/S ratios (over 2). Estimations of the C/S ratio and density of the amorphous C–S–H indicate its progressive decalcification and densification, with the lowest C/S values observed at the highest curing temperatures. This work extends previous studies on the quantitative characterization of Class G cement paste hydrated between 7 and 90 C (Bahafid et al., 2017, 2018), offering a comprehensive understanding of microstructural evolution over a broad temperature range - from 7 to 190 C - during hydration.
本研究考察了在110至190°C高温下水化的水泥浆中C - s - h的微观结构演变和性能变化。采用仅由G类水泥和水组成的简单泥浆配方，通过多种技术方法定量研究了材料的演变，包括力学测试（UCT）、微观结构分析（MIP）和化学表征（TGA和XRD）。结果揭示了导致强度损失的两个关键机制：(1)随着时间的推移，孔隙率和孔径显著增加，导致微观结构粗化；(2)形成更高C/S比（大于2）的致密晶相。对非晶C - S - h的C/S比和密度的估计表明，非晶C - S - h逐渐脱钙和致密化，在最高的固化温度下，C/S值最低。这项工作扩展了之前关于G类水泥浆在7到90°C间水化的定量表征的研究（Bahafid et al., 2017,2018），对水化过程中在7到190°C的大温度范围内的微观结构演变有了全面的了解。
{"title":"Effect of the hydration temperature between 110 and 190 ∘C on the microstructure of Class G cement: Phase composition, pore structure and C–S–H chemistry","authors":"Axelle Alavoine , Math Lecomte , Mickael Saillio , Myriam Duc , Siavash Ghabezloo","doi":"10.1016/j.cemconres.2025.108093","DOIUrl":"10.1016/j.cemconres.2025.108093","url":null,"abstract":"<div><div>This study examines the microstructural evolution and changes in the properties of C–S–H in a cement paste hydrated at elevated temperatures ranging from 110 to 190 <span><math><msup><mrow></mrow><mrow><mo>∘</mo></mrow></msup></math></span>C. Using a simple slurry formulation composed only of Class G cement and water, the material’s evolution was quantitatively investigated through a multi-technique approach, including mechanical testing (UCT), microstructural analysis (MIP), and chemical characterization (TGA and XRD). The results reveal two key mechanisms driving the observed strength loss: (1) a significant increase in porosity and pore size over time, leading to microstructural coarsening, and (2) the formation of denser crystalline phases with higher C/S ratios (over 2). Estimations of the C/S ratio and density of the amorphous C–S–H indicate its progressive decalcification and densification, with the lowest C/S values observed at the highest curing temperatures. This work extends previous studies on the quantitative characterization of Class G cement paste hydrated between 7 and 90 <span><math><msup><mrow></mrow><mrow><mo>∘</mo></mrow></msup></math></span>C (Bahafid et al., 2017, 2018), offering a comprehensive understanding of microstructural evolution over a broad temperature range - from 7 to 190 <span><math><msup><mrow></mrow><mrow><mo>∘</mo></mrow></msup></math></span>C - during hydration.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108093"},"PeriodicalIF":13.1,"publicationDate":"2025-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145575225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-21DOI: 10.1016/j.cemconres.2025.108090
Chancel Mawalala Moundounga , Wahab Abdul , Alexander Pisch , Gavin B.G. Stenning , Cecilia Pesce , Theodore Hanein
Ternesite (Ca5(SiO4)2SO4) is a cementitious phase that can be found in the production of calcium sulfoaluminate (CSA) based cements and other alternative binders. Ternesite has received interest due to its potential hydraulic reactivity (under certain conditions) whilst having a low temperature of formation. Despite this, the ternesite phase is not thermodynamically well understood, reducing the ability to accurately model its formation, stability and phase co-existence in clinker. In this work, pure ternesite was synthesised and the high temperature heat content (874–1174 K) and low temperature heat capacity (2−302K) was measured using drop calorimetry and PPMS respectively. These data were then combined with enthalpy of formation results from DFT and previous experiments to model the thermodynamics properties of ternesite using the 3rd generation CALPHAD function. This allows for a single function to describe the thermodynamic properties of ternesite for use in extending existing thermodynamic databases as part of predictive calculations at a temperature range from 0 K to above the clinkering temperature.
{"title":"Thermodynamic properties of ternesite (Ca5(SiO4)2SO4) from 0 K up to clinkering temperatures","authors":"Chancel Mawalala Moundounga , Wahab Abdul , Alexander Pisch , Gavin B.G. Stenning , Cecilia Pesce , Theodore Hanein","doi":"10.1016/j.cemconres.2025.108090","DOIUrl":"10.1016/j.cemconres.2025.108090","url":null,"abstract":"<div><div>Ternesite (Ca<sub>5</sub>(SiO<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>) is a cementitious phase that can be found in the production of calcium sulfoaluminate (CSA) based cements and other alternative binders. Ternesite has received interest due to its potential hydraulic reactivity (under certain conditions) whilst having a low temperature of formation. Despite this, the ternesite phase is not thermodynamically well understood, reducing the ability to accurately model its formation, stability and phase co-existence in clinker. In this work, pure ternesite was synthesised and the high temperature heat content (874–1174 K) and low temperature heat capacity (2−302<em>K</em>) was measured using drop calorimetry and PPMS respectively. These data were then combined with enthalpy of formation results from DFT and previous experiments to model the thermodynamics properties of ternesite using the 3rd generation CALPHAD function. This allows for a single function to describe the thermodynamic properties of ternesite for use in extending existing thermodynamic databases as part of predictive calculations at a temperature range from 0 K to above the clinkering temperature.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108090"},"PeriodicalIF":13.1,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145567521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-19DOI: 10.1016/j.cemconres.2025.108091
Xiao Xu , Shijie Wang , Haifeng Qin , Zhiqiang Zhao , Zheyong Fan , Zhuhua Zhang , Hang Yin
Tobermorite and Calcium Silicate Hydrate (C-S-H) systems are indispensable cement materials but still lack a satisfactory interatomic potential with both high accuracy and high computational efficiency for better understanding their mechanical performance. Here, we develop a Neuroevolution Machine Learning Potential (NEP) with Ziegler-Biersack-Littmark hybrid framework for tobermorite and C-S-H systems, which conveys unprecedented efficiency in molecular dynamics simulations with substantially reduced training datasets. Our NEP model achieves prediction accuracy comparable to DFT calculations using just around 400 training structures, significantly fewer than other existing machine learning potentials trained for tobermorite. Critically, the GPU-accelerated NEP computations enable scalable simulations of large tobermorite systems, reaching several thousand atoms per GPU card with high efficiency. We demonstrate the NEP's versatility by accurately predicting mechanical properties, phonon density of states, and thermal conductivity of tobermorite. Furthermore, we extend the NEP application to large-scale simulations of amorphous C-S-H, highlighting its potential for comprehensive analysis of structural and mechanical behaviors under various realistic conditions.
{"title":"A high-efficiency neuroevolution potential for tobermorite and calcium silicate hydrate systems with ab initio accuracy","authors":"Xiao Xu , Shijie Wang , Haifeng Qin , Zhiqiang Zhao , Zheyong Fan , Zhuhua Zhang , Hang Yin","doi":"10.1016/j.cemconres.2025.108091","DOIUrl":"10.1016/j.cemconres.2025.108091","url":null,"abstract":"<div><div>Tobermorite and Calcium Silicate Hydrate (C-S-H) systems are indispensable cement materials but still lack a satisfactory interatomic potential with both high accuracy and high computational efficiency for better understanding their mechanical performance. Here, we develop a Neuroevolution Machine Learning Potential (NEP) with Ziegler-Biersack-Littmark hybrid framework for tobermorite and C-S-H systems, which conveys unprecedented efficiency in molecular dynamics simulations with substantially reduced training datasets. Our NEP model achieves prediction accuracy comparable to DFT calculations using just around 400 training structures, significantly fewer than other existing machine learning potentials trained for tobermorite. Critically, the GPU-accelerated NEP computations enable scalable simulations of large tobermorite systems, reaching several thousand atoms per GPU card with high efficiency. We demonstrate the NEP's versatility by accurately predicting mechanical properties, phonon density of states, and thermal conductivity of tobermorite. Furthermore, we extend the NEP application to large-scale simulations of amorphous C-S-H, highlighting its potential for comprehensive analysis of structural and mechanical behaviors under various realistic conditions.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108091"},"PeriodicalIF":13.1,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145554904","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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