Pub Date : 2026-02-01Epub Date: 2025-10-27DOI: 10.1016/j.cemconres.2025.108071
Yanlin Huo , Dong Lu , Chun-ran Wu , Huayang Sun , Xiaoyu Han , Zhitao Chen , Yingzi Yang , Victor C. Li
Engineered cementitious composites (ECC) have previously been found to retain the strain-hardening property with a minimum strain of 2 % tensile ductility even at −60 °C. To examine this notable tensile behavior, pull-out tests were performed on polyethylene (PE) fibers with varying moisture contents, inclinations, and embedded lengths at temperatures ranging from 20 °C to −60 °C. The cold shrinkage and ice effects were identified and quantified as the main factors influencing single fiber pull-out behavior at subzero temperatures. Interfacial frictional bond, apparent fiber strength, snubbing coefficient, and fiber strength reduction coefficient were derived, forming the basis for a subzero-temperatures micromechanical model and the analyses of fiber crack-bridging behavior. Furthermore, the model was validated by comparison with experimental uniaxial tensile stress-strain relationships. This method is anticipated to provide fundamental insights into macroscopic tensile properties at subzero temperatures, aiding the design and application of ECC in cold region engineering.
{"title":"Micromechanical behavior of ECC/SHCC at severe cold temperatures: A comprehensive understanding of single fiber pullout","authors":"Yanlin Huo , Dong Lu , Chun-ran Wu , Huayang Sun , Xiaoyu Han , Zhitao Chen , Yingzi Yang , Victor C. Li","doi":"10.1016/j.cemconres.2025.108071","DOIUrl":"10.1016/j.cemconres.2025.108071","url":null,"abstract":"<div><div>Engineered cementitious composites (ECC) have previously been found to retain the strain-hardening property with a minimum strain of 2 % tensile ductility even at −60 °C. To examine this notable tensile behavior, pull-out tests were performed on polyethylene (PE) fibers with varying moisture contents, inclinations, and embedded lengths at temperatures ranging from 20 °C to −60 °C. The cold shrinkage and ice effects were identified and quantified as the main factors influencing single fiber pull-out behavior at subzero temperatures. Interfacial frictional bond, apparent fiber strength, snubbing coefficient, and fiber strength reduction coefficient were derived, forming the basis for a subzero-temperatures micromechanical model and the analyses of fiber crack-bridging behavior. Furthermore, the model was validated by comparison with experimental uniaxial tensile stress-strain relationships. This method is anticipated to provide fundamental insights into macroscopic tensile properties at subzero temperatures, aiding the design and application of ECC in cold region engineering.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108071"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145383462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-11-26DOI: 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":"2026-02-01","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}
The multi-scale pore structure of cement-based materials (CBMs) holds the key to understanding their performance. Most traditional test methods, such as mercury intrusion porosimetry, require pre-drying, which significantly alters the nanoscale pore structure of CBMs. Although proton NMR transverse relaxometry works well for white CBMs, it fails for Portland CBMs due to the ambiguous effect of Fe2O3. To circumvent this effect, an improved longitudinal relaxometry is established based on a newly proposed method to determine longitudinal surface relaxivity. Experimental results show that the longitudinal relaxometry helps measure the porosities of white and Portland cement mortars (WMs and PMs) with good accuracy. The longitudinal surface relaxivity of PMs was measured as 1.84–2.10 nm/ms, which is comparable to the transverse relaxivity of WMs. According to these obtained pore size distribution curves of water-saturated mortars, their predicted water permeabilities agree well with experimentally measured values, which effectively validates the proposed longitudinal relaxometry.
{"title":"Characterizing pore structure of white and ordinary Portland cement mortars with proton NMR longitudinal relaxometry","authors":"Jing Qiao , Yun Zhang , Huaming Liang , Jiangfeng Guo , Chunsheng Zhou","doi":"10.1016/j.cemconres.2025.108073","DOIUrl":"10.1016/j.cemconres.2025.108073","url":null,"abstract":"<div><div>The multi-scale pore structure of cement-based materials (CBMs) holds the key to understanding their performance. Most traditional test methods, such as mercury intrusion porosimetry, require pre-drying, which significantly alters the nanoscale pore structure of CBMs. Although proton NMR transverse relaxometry works well for white CBMs, it fails for Portland CBMs due to the ambiguous effect of Fe<sub>2</sub>O<sub>3</sub>. To circumvent this effect, an improved longitudinal relaxometry is established based on a newly proposed method to determine longitudinal surface relaxivity. Experimental results show that the longitudinal relaxometry helps measure the porosities of white and Portland cement mortars (WMs and PMs) with good accuracy. The longitudinal surface relaxivity of PMs was measured as 1.84–2.10 nm/ms, which is comparable to the transverse relaxivity of WMs. According to these obtained pore size distribution curves of water-saturated mortars, their predicted water permeabilities agree well with experimentally measured values, which effectively validates the proposed longitudinal relaxometry.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108073"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145383463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-10-25DOI: 10.1016/j.cemconres.2025.108070
Dong Xie, Jianming Gao, Cheng Liu
Limestone is widely used as a mineral admixture in cementitious systems, while the sources of cohesion within the limestone particle network remain unclear, especially in the early hydration stages where significant interactions between particle networks and hydration bonds have not yet developed. In this study, the mixed solutions containing calcium ions (Ca2+), sulfate ions (SO42−), and polycarboxylate ethers (PCE) are used to simulate the complex cementitious environment, and electrokinetic measurements and rheology are conducted to investigate the adsorption mechanisms and interparticle forces. The results indicate that Ca2+ ions, strongly adsorbed onto the surface of limestone particles, acting as potential determining ions, are involved in the reconstruction of cohesive networks, conforming to the classic DLVO theory. In SO42−-regulated suspensions with variable ionic strength, the yield stress exhibits a strong linear correlation with the squared zeta potential. The spatial hindrance and electrostatic repulsion generated by PCE adsorption are weakened due to the competitive adsorption of SO42−, while positive charge sites on particle surface can be effectively supplemented by Ca2+, which mediate the adsorption of PCE and significantly reduce competition with SO42−.
{"title":"Cohesion forces of limestone suspensions: Effects of adsorbed calcium ions, sulfate ions and polycarboxylate ethers","authors":"Dong Xie, Jianming Gao, Cheng Liu","doi":"10.1016/j.cemconres.2025.108070","DOIUrl":"10.1016/j.cemconres.2025.108070","url":null,"abstract":"<div><div>Limestone is widely used as a mineral admixture in cementitious systems, while the sources of cohesion within the limestone particle network remain unclear, especially in the early hydration stages where significant interactions between particle networks and hydration bonds have not yet developed. In this study, the mixed solutions containing calcium ions (Ca<sup>2+</sup>), sulfate ions (SO<sub>4</sub><sup>2−</sup>), and polycarboxylate ethers (PCE) are used to simulate the complex cementitious environment, and electrokinetic measurements and rheology are conducted to investigate the adsorption mechanisms and interparticle forces. The results indicate that Ca<sup>2+</sup> ions, strongly adsorbed onto the surface of limestone particles, acting as potential determining ions, are involved in the reconstruction of cohesive networks, conforming to the classic DLVO theory. In SO<sub>4</sub><sup>2−</sup>-regulated suspensions with variable ionic strength, the yield stress exhibits a strong linear correlation with the squared zeta potential. The spatial hindrance and electrostatic repulsion generated by PCE adsorption are weakened due to the competitive adsorption of SO<sub>4</sub><sup>2−</sup>, while positive charge sites on particle surface can be effectively supplemented by Ca<sup>2+</sup>, which mediate the adsorption of PCE and significantly reduce competition with SO<sub>4</sub><sup>2−</sup>.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108070"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-12-01DOI: 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":"2026-02-01","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 : 2026-02-01Epub Date: 2025-10-28DOI: 10.1016/j.cemconres.2025.108068
Yue Zhang , Pan Feng , Runjie Li , Bo Liu , Lei Lei
Alkali-activated slag (AAS) using Na2CO3 or Na2SiO3 offers less corrosive alternatives to NaOH activation but suffers from severe workability limitations. To address this, we propose calcium supplementation strategy to counteract activator anion-induced Ca2+ depletion, the primary cause of polycarboxylate superplasticizer (PCE) dispersion failure. Through assessment of workability, hydration kinetics and strength development, the compatible PCE was identified as AA-7HPEG4.5. The optimal calcium supplementation was determined to be a molar ratio of 0.75 (Ca2+/CO32−) for the Na2CO3-AAS system and 1:1 (Ca2+/SiO32−) for the Na2SiO3-AAS system. These ratios achieved an optimal balance between workability requirements and mechanical performance. It is hypothesized that this mitigation strategy may extend to other PCEs capable of operating in Na2CO3 or Na2SiO3 systems, provided their dispersing power in NaOH-AAS remains sufficient. However, this extrapolation is pending further experimental validation.
{"title":"A mitigation strategy to improve workability of Na2CO3 or Na2SiO3 activated slag system: Supplementation of calcium salt","authors":"Yue Zhang , Pan Feng , Runjie Li , Bo Liu , Lei Lei","doi":"10.1016/j.cemconres.2025.108068","DOIUrl":"10.1016/j.cemconres.2025.108068","url":null,"abstract":"<div><div>Alkali-activated slag (AAS) using Na<sub>2</sub>CO<sub>3</sub> or Na<sub>2</sub>SiO<sub>3</sub> offers less corrosive alternatives to NaOH activation but suffers from severe workability limitations. To address this, we propose calcium supplementation strategy to counteract activator anion-induced Ca<sup>2+</sup> depletion, the primary cause of polycarboxylate superplasticizer (PCE) dispersion failure. Through assessment of workability, hydration kinetics and strength development, the compatible PCE was identified as AA-7HPEG4.5. The optimal calcium supplementation was determined to be a molar ratio of 0.75 (Ca<sup>2+</sup>/CO<sub>3</sub><sup>2−</sup>) for the Na<sub>2</sub>CO<sub>3</sub>-AAS system and 1:1 (Ca<sup>2+</sup>/SiO<sub>3</sub><sup>2−</sup>) for the Na<sub>2</sub>SiO<sub>3</sub>-AAS system. These ratios achieved an optimal balance between workability requirements and mechanical performance. It is hypothesized that this mitigation strategy may extend to other PCEs capable of operating in Na<sub>2</sub>CO<sub>3</sub> or Na<sub>2</sub>SiO<sub>3</sub> systems, provided their dispersing power in NaOH-AAS remains sufficient. However, this extrapolation is pending further experimental validation.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108068"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145383459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-11-06DOI: 10.1016/j.cemconres.2025.108085
Yangrui Li , Yanfei Yue , Jueshi Qian , Yun Bai
The hydration inertness of ternesite (C5S2Š) is the primary barrier to the promotion of Ternesite-Ye'elimite Cement (TYC). This study investigated the potential of iron-doped calcium aluminates to activate the hydration of TYC systems, with particular focus on their roles in enhancing the reactivity of C5S2Š. Three types of calcium aluminates, viz. orthorhombic ye'elimite (C4A3Š), iron-doped cubic ye'elimite (C4(A,F)3Š) and ferrite (C4AF), as well as C5S2Š were synthesized in the laboratory. These four minerals, and three blends formulated by mixing each calcium aluminate with C5S2Š, were mixed with water to obtain a total of seven paste mixtures. Their hydration processes were examined using ICC, XRD, FT-IR, TG, and pore solution chemistry analysis to elucidate the influence of iron-doped calcium aluminates (C4(A,F)3Š and C4AF) on the hydration reactivity of C5S2Š and the corresponding mechanisms. Results show that C4(A,F)3Š significantly enhanced the hydration reactivity of C5S2Š by providing reactive amorphous (A,F)H3 to consume gypsum from the hydration of C5S2Š. Evidently, iron doping exhibited a gypsum-like acceleration effect on the hydration of C5S2Š + C4(A,F)3Š system, albeit through a distinct chemical pathway. However, C4AF demonstrated quite limited effect on the C5S2Š + C4AF system, due to the gradual formation of a gel layer on the C4AF surface that restricted further hydration.
{"title":"Can iron-doped calcium aluminates activate ternesite hydration?","authors":"Yangrui Li , Yanfei Yue , Jueshi Qian , Yun Bai","doi":"10.1016/j.cemconres.2025.108085","DOIUrl":"10.1016/j.cemconres.2025.108085","url":null,"abstract":"<div><div>The hydration inertness of ternesite (C<sub>5</sub>S<sub>2</sub>Š) is the primary barrier to the promotion of Ternesite-Ye'elimite Cement (TYC). This study investigated the potential of iron-doped calcium aluminates to activate the hydration of TYC systems, with particular focus on their roles in enhancing the reactivity of C<sub>5</sub>S<sub>2</sub>Š. Three types of calcium aluminates, viz. orthorhombic ye'elimite (C<sub>4</sub>A<sub>3</sub>Š), iron-doped cubic ye'elimite (C<sub>4</sub>(A,F)<sub>3</sub>Š) and ferrite (C<sub>4</sub>AF), as well as C<sub>5</sub>S<sub>2</sub>Š were synthesized in the laboratory. These four minerals, and three blends formulated by mixing each calcium aluminate with C<sub>5</sub>S<sub>2</sub>Š, were mixed with water to obtain a total of seven paste mixtures. Their hydration processes were examined using ICC, XRD, FT-IR, TG, and pore solution chemistry analysis to elucidate the influence of iron-doped calcium aluminates (C<sub>4</sub>(A,F)<sub>3</sub>Š and C<sub>4</sub>AF) on the hydration reactivity of C<sub>5</sub>S<sub>2</sub>Š and the corresponding mechanisms. Results show that C<sub>4</sub>(A,F)<sub>3</sub>Š significantly enhanced the hydration reactivity of C<sub>5</sub>S<sub>2</sub>Š by providing reactive amorphous (A,F)H<sub>3</sub> to consume gypsum from the hydration of C<sub>5</sub>S<sub>2</sub>Š. Evidently, iron doping exhibited a gypsum-like acceleration effect on the hydration of C<sub>5</sub>S<sub>2</sub>Š + C<sub>4</sub>(A,F)<sub>3</sub>Š system, albeit through a distinct chemical pathway. However, C<sub>4</sub>AF demonstrated quite limited effect on the C<sub>5</sub>S<sub>2</sub>Š + C<sub>4</sub>AF system, due to the gradual formation of a gel layer on the C<sub>4</sub>AF surface that restricted further hydration.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108085"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145447421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-10-27DOI: 10.1016/j.cemconres.2025.108064
L.C. Queiroz , W.S. Barbosa , M.D.S. de Lima , I.N.L. Paes , A.P. Kirchheim , C.P. Bergmann
Doping during Portland cement clinker synthesis significantly influences the stabilization and reactivity of tricalcium silicate (C3S) polymorphs. Therefore, this study investigates the effect of MgO, ZnO, and TiO2 doping (at 0.5 and 1.0 wt%) on the structural and hydration behavior of C3S. Synthesis was performed at 1500 °C for six hours, followed by characterization using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) surface area analysis, and isothermal calorimetry. To further assess the catalytic effects of dopant ions on C3S hydration, higher doping levels (4.0 and 8.0 wt%) were also evaluated. The results show that doping promotes stabilization of the T3, M1, and M3 C3S polymorphs. Among the dopants, MgO-enhanced phases exhibited higher intrinsic reactivity. However, despite this increased reactivity, hydration rates were reduced across all systems due to a dual effect: catalytic interactions with the hydration products and the formation of a physical barrier by excess dopant. These findings provide new insights into the design of doped clinker systems for tailored hydration performance.
{"title":"Effect of ionic doping on the structure and reactivity of Portland cement tricalcium silicate","authors":"L.C. Queiroz , W.S. Barbosa , M.D.S. de Lima , I.N.L. Paes , A.P. Kirchheim , C.P. Bergmann","doi":"10.1016/j.cemconres.2025.108064","DOIUrl":"10.1016/j.cemconres.2025.108064","url":null,"abstract":"<div><div>Doping during Portland cement clinker synthesis significantly influences the stabilization and reactivity of tricalcium silicate (C<sub>3</sub>S) polymorphs. Therefore, this study investigates the effect of MgO, ZnO, and TiO<sub>2</sub> doping (at 0.5 and 1.0 wt%) on the structural and hydration behavior of C<sub>3</sub>S. Synthesis was performed at 1500 °C for six hours, followed by characterization using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) surface area analysis, and isothermal calorimetry. To further assess the catalytic effects of dopant ions on C<sub>3</sub>S hydration, higher doping levels (4.0 and 8.0 wt%) were also evaluated. The results show that doping promotes stabilization of the T3, M1, and M3 C<sub>3</sub>S polymorphs. Among the dopants, MgO-enhanced phases exhibited higher intrinsic reactivity. However, despite this increased reactivity, hydration rates were reduced across all systems due to a dual effect: catalytic interactions with the hydration products and the formation of a physical barrier by excess dopant. These findings provide new insights into the design of doped clinker systems for tailored hydration performance.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108064"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145383654","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":"2026-02-01","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 : 2026-02-01Epub Date: 2025-11-03DOI: 10.1016/j.cemconres.2025.108072
Guangqi Xiong , Zheng Fang , Yuanliang Ren , Xiaolong Jia , Hongkuang Luo , Jiaxin Yang , Bo Ran , Shuai Zhou , Chong Wang
To address the limitations of conventional vibration in removing microbubbles from cement paste, this study introduces power ultrasound as a novel defoaming technology and investigates its effectiveness and mechanism. Experiments conducted at a water-to-cement ratio of 0.50, with or without air-entraining agents, and demonstrated that ultrasound treatment effectively eliminated microbubbles, as confirmed by 1H NMR and FBRM analyses. Compared to controls, treated batches exhibited increases in compressive strength of 17.1 % and 7.3 % at 3 days, and 6.8 % and 3.8 % at 28 days. Modeling indicates that bubbles move towards the pressure node once ultrasound is applied, and whether bubble coalescence occurs is primarily governed by the secondary Bjerknes force. Coalesced bubbles will then rise due to increased buoyancy. These findings highlight the significant potential of power ultrasound as an innovative and efficient defoaming technology for cement-based materials, offering improved microstructure and mechanical performance.
{"title":"A novel defoaming technology for cement paste by using power ultrasound treatment","authors":"Guangqi Xiong , Zheng Fang , Yuanliang Ren , Xiaolong Jia , Hongkuang Luo , Jiaxin Yang , Bo Ran , Shuai Zhou , Chong Wang","doi":"10.1016/j.cemconres.2025.108072","DOIUrl":"10.1016/j.cemconres.2025.108072","url":null,"abstract":"<div><div>To address the limitations of conventional vibration in removing microbubbles from cement paste, this study introduces power ultrasound as a novel defoaming technology and investigates its effectiveness and mechanism. Experiments conducted at a water-to-cement ratio of 0.50, with or without air-entraining agents, and demonstrated that ultrasound treatment effectively eliminated microbubbles, as confirmed by <sup>1</sup>H NMR and FBRM analyses. Compared to controls, treated batches exhibited increases in compressive strength of 17.1 % and 7.3 % at 3 days, and 6.8 % and 3.8 % at 28 days. Modeling indicates that bubbles move towards the pressure node once ultrasound is applied, and whether bubble coalescence occurs is primarily governed by the secondary Bjerknes force. Coalesced bubbles will then rise due to increased buoyancy. These findings highlight the significant potential of power ultrasound as an innovative and efficient defoaming technology for cement-based materials, offering improved microstructure and mechanical performance.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"200 ","pages":"Article 108072"},"PeriodicalIF":13.1,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145434840","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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