Pub Date : 2025-03-21DOI: 10.1016/j.cemconres.2025.107869
Michal Hlobil, Luca Michel, Mohit Pundir, David S. Kammer
Cold joints in extruded concrete structures form once the exposed surface of a deposited filament dries prematurely and gets sequentially covered by a layer of fresh concrete. This creates a material heterogeneity which lowers the structural durability and shortens the designed service life. Many factors concurrently affect cold joint formation, yet a suitable tool for their categorization is missing. Here, we present a computational model that simulates the drying kinetics at the exposed structural surface, accounting for cement hydration and the resulting microstructural development. The model provides a time estimate for cold joint formation as a result. It allows us to assess the drying severity for a given geometry of the structure, its interaction with the environment, and ambient conditions. We evaluate the assessed factors and provide generalized recommendations for cold joint mitigation.
{"title":"A thermo-hygro model to determine the factors dictating cold joint formation in 3D printed concrete","authors":"Michal Hlobil, Luca Michel, Mohit Pundir, David S. Kammer","doi":"10.1016/j.cemconres.2025.107869","DOIUrl":"https://doi.org/10.1016/j.cemconres.2025.107869","url":null,"abstract":"Cold joints in extruded concrete structures form once the exposed surface of a deposited filament dries prematurely and gets sequentially covered by a layer of fresh concrete. This creates a material heterogeneity which lowers the structural durability and shortens the designed service life. Many factors concurrently affect cold joint formation, yet a suitable tool for their categorization is missing. Here, we present a computational model that simulates the drying kinetics at the exposed structural surface, accounting for cement hydration and the resulting microstructural development. The model provides a time estimate for cold joint formation as a result. It allows us to assess the drying severity for a given geometry of the structure, its interaction with the environment, and ambient conditions. We evaluate the assessed factors and provide generalized recommendations for cold joint mitigation.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"92 1","pages":""},"PeriodicalIF":11.4,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143666463","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 : 2025-03-20DOI: 10.1016/j.cemconres.2025.107853
Olivia Rindle, Florian Sixt, Liam Spillane, Elena Willinger, Torben Gädt
Ettringite forms directly after Portland cement is mixed with water. Polycarboxylate ether-type superplasticizers can stabilize nano-ettringite particles in the pore solution and modify ettringite formation. It was previously impossible to isolate the nano-ettringite from the cement pore solution at commonly used water-to-cement (w/c) ratios of 0.5 and lower. Therefore, the exact morphology of ettringite in the pore solution has not been systematically studied. This paper presents a novel method for obtaining nano-ettringite from cement paste by centrifugation with a high-density liquid. Ettringite was isolated at three different water-to-cement ratios (0.3, 0.4, and 0.5) and four dosages of a polycarboxylate ether-type superplasticizer (0.05%, 0.1%, 0.25%, and 0.4%). The size and morphology of the obtained ettringite particles were analyzed using transmission electron microscopy (TEM). The chemical composition and structure of ettringite were confirmed using electron energy loss spectroscopy, high-resolution TEM imaging, and X-ray diffraction. The ettringite particle size decreases as the superplasticizer dosage increases. As a result, the specific surface area at higher superplasticizer dosages increases from 39 m2 g−1 to 58 m2 g−1. In-situ calorimetry was used to measure the initial heat release and estimate the amount of ettringite formed. Since the initial heat did not change significantly with varying superplasticizer dosages, it suggests that the studied superplasticizer has a minor influence on the amount of ettringite at the considered concentrations. In summary, cement paste centrifugation using a high-density fluid allows the isolation of superplasticizer-stabilized nano-ettringite from cement paste. The method could be valuable for other studies dealing with the impact of ettringite morphology.
波特兰水泥与水混合后会直接形成闪长岩。聚羧酸醚类超塑化剂可以稳定孔隙溶液中的纳米闪长岩颗粒，并改变闪长岩的形成。以前，当常用的水灰比（w/c）为 0.5 或更低时，无法从水泥孔隙溶液中分离出纳米铁素体。因此，孔隙溶液中埃特林岩的确切形态尚未得到系统研究。本文介绍了一种通过高密度液体离心从水泥浆中获得纳米埃曲沸石的新方法。在三种不同的水灰比（0.3、0.4 和 0.5）和四种聚羧酸醚型超塑化剂用量（0.05%、0.1%、0.25% 和 0.4%）条件下分离出了埃丁石。利用透射电子显微镜（TEM）分析了所获得的乙曲石颗粒的尺寸和形态。利用电子能量损失光谱、高分辨率 TEM 成像和 X 射线衍射确认了埃曲沸石的化学成分和结构。随着超塑化剂用量的增加，埃曲沸石的粒径减小。因此，在较高的超塑化剂用量下，比表面积从 39 m2 g-1 增加到 58 m2 g-1。采用原位量热法测量初始放热量，并估算形成的乙丁睛石量。由于初始热量并没有随着超塑化剂用量的变化而发生显著变化，这表明所研究的超塑化剂在所考虑的浓度下对乙曲石的数量影响较小。总之，使用高密度流体对水泥浆进行离心分离，可以从水泥浆中分离出超塑化剂稳定的纳米乙丁睛石。这种方法对于其他涉及乙丁睛石形态影响的研究很有价值。
{"title":"Revealing the morphology of nano-ettringite in cement paste: A TEM study on the influence of polycarboxylate ether superplasticizers","authors":"Olivia Rindle, Florian Sixt, Liam Spillane, Elena Willinger, Torben Gädt","doi":"10.1016/j.cemconres.2025.107853","DOIUrl":"https://doi.org/10.1016/j.cemconres.2025.107853","url":null,"abstract":"Ettringite forms directly after Portland cement is mixed with water. Polycarboxylate ether-type superplasticizers can stabilize nano-ettringite particles in the pore solution and modify ettringite formation. It was previously impossible to isolate the nano-ettringite from the cement pore solution at commonly used water-to-cement (w/c) ratios of 0.5 and lower. Therefore, the exact morphology of ettringite in the pore solution has not been systematically studied. This paper presents a novel method for obtaining nano-ettringite from cement paste by centrifugation with a high-density liquid. Ettringite was isolated at three different water-to-cement ratios (0.3, 0.4, and 0.5) and four dosages of a polycarboxylate ether-type superplasticizer (0.05%, 0.1%, 0.25%, and 0.4%). The size and morphology of the obtained ettringite particles were analyzed using transmission electron microscopy (TEM). The chemical composition and structure of ettringite were confirmed using electron energy loss spectroscopy, high-resolution TEM imaging, and X-ray diffraction. The ettringite particle size decreases as the superplasticizer dosage increases. As a result, the specific surface area at higher superplasticizer dosages increases from 39<!-- --> <!-- -->m<sup>2</sup> <!-- -->g<sup>−1</sup> to 58<!-- --> <!-- -->m<sup>2</sup> <!-- -->g<sup>−1</sup>. In-situ calorimetry was used to measure the initial heat release and estimate the amount of ettringite formed. Since the initial heat did not change significantly with varying superplasticizer dosages, it suggests that the studied superplasticizer has a minor influence on the amount of ettringite at the considered concentrations. In summary, cement paste centrifugation using a high-density fluid allows the isolation of superplasticizer-stabilized nano-ettringite from cement paste. The method could be valuable for other studies dealing with the impact of ettringite morphology.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"91 1","pages":""},"PeriodicalIF":11.4,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660436","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 : 2025-03-18DOI: 10.1016/j.cemconres.2025.107871
Zian Tang , Yuanrui Song , Wenyu Li
The alkali-activation process is known to be rapid and thus challenging to characterize. In this work, we used proton density magnetic resonance imaging (PD-MRI) to observe the water distribution during the alkali-activation process of metakaolin. With the obtained visible brightness changing of the solid phase and the bled water, the setting time of the alkali-activated materials (AAMs) can be determined, while the migration of paramagnetic contents (Fe) and the accumulation of unreacted base can be traced. Moreover, the total shrinkage of the activated paste was calculated for the first time based on MRI in this manuscript. The results show the potential use of this technique for characterizing AAMs with lower paramagnetic content.
{"title":"Analysis of time-resolved water distribution and paramagnetic contents migration during alkali-activation process of Metakaolin using PD-MRI","authors":"Zian Tang , Yuanrui Song , Wenyu Li","doi":"10.1016/j.cemconres.2025.107871","DOIUrl":"10.1016/j.cemconres.2025.107871","url":null,"abstract":"<div><div>The alkali-activation process is known to be rapid and thus challenging to characterize. In this work, we used proton density magnetic resonance imaging (PD-MRI) to observe the water distribution during the alkali-activation process of metakaolin. With the obtained visible brightness changing of the solid phase and the bled water, the setting time of the alkali-activated materials (AAMs) can be determined, while the migration of paramagnetic contents (Fe) and the accumulation of unreacted base can be traced. Moreover, the total shrinkage of the activated paste was calculated for the first time based on MRI in this manuscript. The results show the potential use of this technique for characterizing AAMs with lower paramagnetic content.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"193 ","pages":"Article 107871"},"PeriodicalIF":10.9,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143640560","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 : 2025-03-17DOI: 10.1016/j.cemconres.2025.107876
Junjie You , Yanrong Zhang , Cheng Yang , Qianyi Song , Yi Sun
Basic magnesium sulfate cement (BMSC) contains excess MgO causing volume instability, limiting its applications. Although forced carbonation stabilizes MgO into carbonates, it compromises strength by transforming strength-contributing phases. This study presents a forced carbonation strategy based on hierarchical pore regulation. We constructed a multi-scale pore network from nano to macro scale, optimizing CO2 diffusion channels and carbonation product deposition space through synergy of basalt fiber and recycled wood fiber. The system exhibits a three-stage mechanism during forced carbonation: pressure-driven dissolution, filling-directed reconstruction, and self-regulating evolution. Under this mechanism, the developed carbonated bio-based magnesium sulfate (CBMS) cement overcame post‑carbonation limitations and exhibited increases of 79.3% and 19.1% in compressive and flexural strength respectively through the synergistic effect of fiber toughening and carbonation filling. The coupling mechanism between hierarchical pore structure evolution and carbonation behavior further achieved a 215.3% increase in carbonation degree and a 59.9% reduction in global warming potential.
{"title":"Hierarchical pore structure for enhanced carbonation in basic magnesium sulfate cement: Mechanisms from modification to post‑carbonation evolution","authors":"Junjie You , Yanrong Zhang , Cheng Yang , Qianyi Song , Yi Sun","doi":"10.1016/j.cemconres.2025.107876","DOIUrl":"10.1016/j.cemconres.2025.107876","url":null,"abstract":"<div><div>Basic magnesium sulfate cement (BMSC) contains excess MgO causing volume instability, limiting its applications. Although forced carbonation stabilizes MgO into carbonates, it compromises strength by transforming strength-contributing phases. This study presents a forced carbonation strategy based on hierarchical pore regulation. We constructed a multi-scale pore network from nano to macro scale, optimizing CO<sub>2</sub> diffusion channels and carbonation product deposition space through synergy of basalt fiber and recycled wood fiber. The system exhibits a three-stage mechanism during forced carbonation: pressure-driven dissolution, filling-directed reconstruction, and self-regulating evolution. Under this mechanism, the developed carbonated bio-based magnesium sulfate (CBMS) cement overcame post‑carbonation limitations and exhibited increases of 79.3% and 19.1% in compressive and flexural strength respectively through the synergistic effect of fiber toughening and carbonation filling. The coupling mechanism between hierarchical pore structure evolution and carbonation behavior further achieved a 215.3% increase in carbonation degree and a 59.9% reduction in global warming potential.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"193 ","pages":"Article 107876"},"PeriodicalIF":10.9,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143635369","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 : 2025-03-17DOI: 10.1016/j.cemconres.2025.107877
Chen Liu , Jinbao Xie , Zhenming Li , Guang Ye
Cementitious materials can achieve desirable strength development and reduced cracking potential under moist or immersed conditions. However, in this work, we found that alkali-activated slag (AAS) pastes can crack underwater, with a higher silicate modulus showing more pronounced cracking. Chemically, the C-(N-)A-S-H gel in the paste with a higher silicate modulus showed a higher Na/Si ratio and a higher leaching loss of Na, which led to more significant structural changes and gel deterioration underwater. This triggered the propagation of cracks initially present in the material. Physically, the paste with a higher silicate modulus featured a denser microstructure, lower water permeability and higher pore pressure, which resulted in a steeper gradient of pore pressure in the matrix. Consequently, the concentration of tensile stress was simulated at the centre and the corner of the cross-section of the sample. As this simulated concentrated stress exceeded the flexural strength of AAS pastes, significant fractures at the centre and spalling at the corner occurred, consistent with the experimental observation. This work not only elucidated the cracking mechanisms of AAS materials underwater but also provided new insights into mixture designs for these materials under high-humidity conditions.
{"title":"An experimental and numerical study on the cracking of alkali-activated slag pastes induced by water immersion","authors":"Chen Liu , Jinbao Xie , Zhenming Li , Guang Ye","doi":"10.1016/j.cemconres.2025.107877","DOIUrl":"10.1016/j.cemconres.2025.107877","url":null,"abstract":"<div><div>Cementitious materials can achieve desirable strength development and reduced cracking potential under moist or immersed conditions. However, in this work, we found that alkali-activated slag (AAS) pastes can crack underwater, with a higher silicate modulus showing more pronounced cracking. Chemically, the C-(N-)A-S-H gel in the paste with a higher silicate modulus showed a higher Na/Si ratio and a higher leaching loss of Na, which led to more significant structural changes and gel deterioration underwater. This triggered the propagation of cracks initially present in the material. Physically, the paste with a higher silicate modulus featured a denser microstructure, lower water permeability and higher pore pressure, which resulted in a steeper gradient of pore pressure in the matrix. Consequently, the concentration of tensile stress was simulated at the centre and the corner of the cross-section of the sample. As this simulated concentrated stress exceeded the flexural strength of AAS pastes, significant fractures at the centre and spalling at the corner occurred, consistent with the experimental observation. This work not only elucidated the cracking mechanisms of AAS materials underwater but also provided new insights into mixture designs for these materials under high-humidity conditions.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"193 ","pages":"Article 107877"},"PeriodicalIF":10.9,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143635360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-14DOI: 10.1016/j.cemconres.2025.107874
José Aguirre Castillo , Bodil Wilhelmsson , Markus Broström , Matias Eriksson
This study investigates the effects of a high-CO2 atmosphere on phase evolution, burnability, and clinker mineral formation in cement raw meals using high-temperature X-ray diffraction (HT-XRD). The cement industry is a significant CO2 emitter, primarily from limestone decomposition and fuel combustion. Innovative solutions such as carbon capture and storage (CCS) are critical, with electrification and oxy-fuel combustion showing promise. Electrification using plasma technology, which employs CO2 as a carrier gas, offers a pathway to near-zero emissions.
Four industrial raw meals from northern Europe were analyzed under conventional (20% CO2) and high-CO2 (95% CO2) conditions. Chemical composition, particle size distribution, and coarse fraction analyses preceded HT-XRD data collection across temperatures up to 1500 °C. High-CO2 conditions delayed calcite decomposition, reducing free-CaO availability and altering burnability. The timing of calcite decomposition relative to C2S formation suggests a reaction pathway in which free CaO, released from calcite, rapidly reacts with thermally activated SiO2 to form C2S. Additionally, spurrite decomposition released reactive CaO and C2S, enhancing C3S formation at 1300–1400 °C in spurrite-rich samples. Above 1400 °C, melt formation promoted further C3S development, leading to similar final levels in both tested atmospheres.
These findings indicate that high-CO2 conditions significantly influence clinker phase evolution and reactivity. Practical implications include optimizing raw meal composition and kiln temperature profiles in electrified and oxy-fuel systems to enhance burnability while minimizing operational issues such as spurrite-induced kiln buildup. Future research should further explore industrial scalability and raw material adjustments to enhance CO2 efficiency during clinkerization.
{"title":"Phase evolution of cement raw meal in a high-CO2 atmosphere","authors":"José Aguirre Castillo , Bodil Wilhelmsson , Markus Broström , Matias Eriksson","doi":"10.1016/j.cemconres.2025.107874","DOIUrl":"10.1016/j.cemconres.2025.107874","url":null,"abstract":"<div><div>This study investigates the effects of a high-CO<sub>2</sub> atmosphere on phase evolution, burnability, and clinker mineral formation in cement raw meals using high-temperature X-ray diffraction (HT-XRD). The cement industry is a significant CO<sub>2</sub> emitter, primarily from limestone decomposition and fuel combustion. Innovative solutions such as carbon capture and storage (CCS) are critical, with electrification and oxy-fuel combustion showing promise. Electrification using plasma technology, which employs CO<sub>2</sub> as a carrier gas, offers a pathway to near-zero emissions.</div><div>Four industrial raw meals from northern Europe were analyzed under conventional (20% CO<sub>2</sub>) and high-CO<sub>2</sub> (95% CO<sub>2</sub>) conditions. Chemical composition, particle size distribution, and coarse fraction analyses preceded HT-XRD data collection across temperatures up to 1500 °C. High-CO<sub>2</sub> conditions delayed calcite decomposition, reducing free-CaO availability and altering burnability. The timing of calcite decomposition relative to C<sub>2</sub>S formation suggests a reaction pathway in which free CaO, released from calcite, rapidly reacts with thermally activated SiO<sub>2</sub> to form C<sub>2</sub>S. Additionally, spurrite decomposition released reactive CaO and C<sub>2</sub>S, enhancing C<sub>3</sub>S formation at 1300–1400 °C in spurrite-rich samples. Above 1400 °C, melt formation promoted further C<sub>3</sub>S development, leading to similar final levels in both tested atmospheres.</div><div>These findings indicate that high-CO<sub>2</sub> conditions significantly influence clinker phase evolution and reactivity. Practical implications include optimizing raw meal composition and kiln temperature profiles in electrified and oxy-fuel systems to enhance burnability while minimizing operational issues such as spurrite-induced kiln buildup. Future research should further explore industrial scalability and raw material adjustments to enhance CO<sub>2</sub> efficiency during clinkerization.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"193 ","pages":"Article 107874"},"PeriodicalIF":10.9,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143618620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ultra-high toughness cementitious composites (UHTCC) are increasingly employed to repair and strengthen deteriorated concrete structures, yet the critical microstructural evolution and micromechanical properties of overlay transition zone (OTZ) remain underexplored. We report a comprehensive, curing time-dependent study of OTZ between cast and sprayed UHTCC and concrete substrates (CS). The findings reveal a dual-scale OTZ structure: (1) the narrow OTZ, impacted by the wall effect, and (2) the broad OTZ, comprising an air void-rich area, the narrow OTZ, and a reaction zone on the CS surface. The thickness of the broad OTZ, governed mainly by the air void-rich area, decreases over time to around 200 μm at 28 days in cast specimens. Spraying shows a dual effect on the broad OTZ, reducing interfacial gaps at 3 days by enhancing UHTCC-CS contact while generating a thicker (300 μm) air void-rich zone at 28 days. Ion migration from UHTCC to the CS surface increases the local mean elastic modulus through the formation of secondary hydrates, like calcium hydroxide and C-(A-)S-H gels. Ulteriorly, we discuss and summarize the evolution mechanisms driving the microstructure and micromechanical properties of OTZ. These insights lay the foundation for the bottom-up, cost-effective engineering regulation of OTZ in concrete repair.
{"title":"Overlay transition zone in concrete repair: Insights into microstructural evolution and micromechanical properties","authors":"Facheng Song, Qinghua Li, Chaokun Hong, Shilang Xu","doi":"10.1016/j.cemconres.2025.107868","DOIUrl":"10.1016/j.cemconres.2025.107868","url":null,"abstract":"<div><div>Ultra-high toughness cementitious composites (UHTCC) are increasingly employed to repair and strengthen deteriorated concrete structures, yet the critical microstructural evolution and micromechanical properties of overlay transition zone (OTZ) remain underexplored. We report a comprehensive, curing time-dependent study of OTZ between cast and sprayed UHTCC and concrete substrates (CS). The findings reveal a dual-scale OTZ structure: (1) the narrow OTZ, impacted by the wall effect, and (2) the broad OTZ, comprising an air void-rich area, the narrow OTZ, and a reaction zone on the CS surface. The thickness of the broad OTZ, governed mainly by the air void-rich area, decreases over time to around 200 μm at 28 days in cast specimens. Spraying shows a dual effect on the broad OTZ, reducing interfacial gaps at 3 days by enhancing UHTCC-CS contact while generating a thicker (300 μm) air void-rich zone at 28 days. Ion migration from UHTCC to the CS surface increases the local mean elastic modulus through the formation of secondary hydrates, like calcium hydroxide and C-(A-)S-H gels. Ulteriorly, we discuss and summarize the evolution mechanisms driving the microstructure and micromechanical properties of OTZ. These insights lay the foundation for the bottom-up, cost-effective engineering regulation of OTZ in concrete repair.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"193 ","pages":"Article 107868"},"PeriodicalIF":10.9,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143611077","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 : 2025-03-13DOI: 10.1016/j.cemconres.2025.107870
Jungang Yuan , Jun Chang , Yun Bai
Ternesite exhibits significant carbonation reactivity and the resultant carbonation products show favorable effects on the performance of Portland cement. Therefore, this study investigated the effects of semi-dry carbonated ternesite on the hydration and hardening characteristics of Portland cement when utilized as a supplementary cementitious material (SCM). The results indicate that the carbonation reaction of ternesite tended to reach a plateau after 10 min, as the formation of calcium carbonate wrapping layer inhibit further carbonation. The carbonation products include calcite, aragonite, vaterite, poorly crystalline calcium carbonate (PCCC), silica gel, gypsum and bassanite, and all of which can contribute to the formation of calcium silicate hydrate (C-S-H) and ettringite in the cement matrix. Moderately carbonated ternesite appears to accelerate cement hydration and densify the pore structure of matrix, thereby continuously promoting the strength development of hardened cement paste over time while this effect diminished with excessive carbonation. Optimal carbonation of ternesite at a degree of carbonation (DOC) of 40.4% achieved the highest 28-day activity index of 95.8% of SCM. Furthermore, sustainability analysis suggests that utilizing carbonated ternesite as a SCM could reduce CO2 emission by 107.8 kg per tonne of cement prepared. This research provides new insights for the development of novel low-carbon cement with high strength.
{"title":"Preparation of supplementary cementitious material by semi-dry carbonated ternesite and its effect on hydration and mechanical properties of Portland cement","authors":"Jungang Yuan , Jun Chang , Yun Bai","doi":"10.1016/j.cemconres.2025.107870","DOIUrl":"10.1016/j.cemconres.2025.107870","url":null,"abstract":"<div><div>Ternesite exhibits significant carbonation reactivity and the resultant carbonation products show favorable effects on the performance of Portland cement. Therefore, this study investigated the effects of semi-dry carbonated ternesite on the hydration and hardening characteristics of Portland cement when utilized as a supplementary cementitious material (SCM). The results indicate that the carbonation reaction of ternesite tended to reach a plateau after 10 min, as the formation of calcium carbonate wrapping layer inhibit further carbonation. The carbonation products include calcite, aragonite, vaterite, poorly crystalline calcium carbonate (PCCC), silica gel, gypsum and bassanite, and all of which can contribute to the formation of calcium silicate hydrate (C-S-H) and ettringite in the cement matrix. Moderately carbonated ternesite appears to accelerate cement hydration and densify the pore structure of matrix, thereby continuously promoting the strength development of hardened cement paste over time while this effect diminished with excessive carbonation. Optimal carbonation of ternesite at a degree of carbonation (DOC) of 40.4% achieved the highest 28-day activity index of 95.8% of SCM. Furthermore, sustainability analysis suggests that utilizing carbonated ternesite as a SCM could reduce CO<sub>2</sub> emission by 107.8 kg per tonne of cement prepared. This research provides new insights for the development of novel low-carbon cement with high strength.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"193 ","pages":"Article 107870"},"PeriodicalIF":10.9,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143608744","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 : 2025-03-13DOI: 10.1016/j.cemconres.2025.107852
Maxime Pierre, Marcos Samudio, Siavash Ghabezloo, Patrick Dangla
Modelling cement-based materials from the early-age to the hardened state is crucial in numerous applications such as deep well cementing or 3D printing, which require comprehensive modelling of multiphysics couplings. To answer these requirements, a thermodynamically consistent time-dependent constitutive model based on the extent of hydration is developed in the framework of thermoporomechanics of partially saturated materials. Using minimal fitting, complex undrained oedometric tests on hydrating cement paste, combining effects of hydration progress, pore pressure evolution, elastic, viscous, and plastic deformations, are well reproduced numerically. In particular, the impact of early-age loading on the behaviour at a subsequent age, paramount in oil-well applications to understanding the consequences of pressurising the casing when the cement sheath is partially hydrated, is explained and quantitatively reproduced.
{"title":"Modelling the poromechanical behaviour of class G cement paste: A multiphysics approach from early age to hardened state","authors":"Maxime Pierre, Marcos Samudio, Siavash Ghabezloo, Patrick Dangla","doi":"10.1016/j.cemconres.2025.107852","DOIUrl":"10.1016/j.cemconres.2025.107852","url":null,"abstract":"<div><div>Modelling cement-based materials from the early-age to the hardened state is crucial in numerous applications such as deep well cementing or 3D printing, which require comprehensive modelling of multiphysics couplings. To answer these requirements, a thermodynamically consistent time-dependent constitutive model based on the extent of hydration is developed in the framework of thermoporomechanics of partially saturated materials. Using minimal fitting, complex undrained oedometric tests on hydrating cement paste, combining effects of hydration progress, pore pressure evolution, elastic, viscous, and plastic deformations, are well reproduced numerically. In particular, the impact of early-age loading on the behaviour at a subsequent age, paramount in oil-well applications to understanding the consequences of pressurising the casing when the cement sheath is partially hydrated, is explained and quantitatively reproduced.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"193 ","pages":"Article 107852"},"PeriodicalIF":10.9,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143608302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-13DOI: 10.1016/j.cemconres.2025.107873
Yannick H. Emminger, Luca Ladner, Cristina Ruiz-Agudo
The use of SCMs as partial substitutes for PC has made C-A-S-H a key binding phase in modern cement, yet its crystallization mechanism remains elusive. This study investigates the early stages of synthetic C-A-S-H formation and compares them with C-S-H using double addition of stoichiometric calcium and silicon amounts at a Ca/Al ratio of 5. Through real-time monitoring of solution parameters—transmittance, free Ca2+ conductivity, and pH—complemented by structural and morphological characterization (FTIR, XRD, SEM, TEM, and NMR), we demonstrate that C-A-S-H formation is at least a two-step process involving amorphous globules, which then evolve into foil-like particles with higher crystallinity. Additionally, we reveal that Al promotes Ca binding during the prenucleation stage and slightly accelerates nucleation. These results highlight important differences in the formation pathways of both hydrates, particularly the extended stability of the C-A-S-H globules, which might affect the workability and setting time in aluminium-containing blended cements.
{"title":"Comparative study of the early stages of crystallization of calcium silicate hydrate (C-S-H) and calcium aluminate silicate hydrate (C-A-S-H)","authors":"Yannick H. Emminger, Luca Ladner, Cristina Ruiz-Agudo","doi":"10.1016/j.cemconres.2025.107873","DOIUrl":"10.1016/j.cemconres.2025.107873","url":null,"abstract":"<div><div>The use of SCMs as partial substitutes for PC has made C-A-S-H a key binding phase in modern cement, yet its crystallization mechanism remains elusive. This study investigates the early stages of synthetic C-A-S-H formation and compares them with C-S-H using double addition of stoichiometric calcium and silicon amounts at a Ca/Al ratio of 5. Through real-time monitoring of solution parameters—transmittance, free Ca<sup>2+</sup> conductivity, and pH—complemented by structural and morphological characterization (FTIR, XRD, SEM, TEM, and NMR), we demonstrate that C-A-S-H formation is at least a two-step process involving amorphous globules, which then evolve into foil-like particles with higher crystallinity. Additionally, we reveal that Al promotes Ca binding during the prenucleation stage and slightly accelerates nucleation. These results highlight important differences in the formation pathways of both hydrates, particularly the extended stability of the C-A-S-H globules, which might affect the workability and setting time in aluminium-containing blended cements.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"193 ","pages":"Article 107873"},"PeriodicalIF":10.9,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143608516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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