Pub Date : 2025-01-17DOI: 10.1016/j.cemconres.2025.107787
Tillmann Schramm, Jürgen Neubauer, Friedlinde Goetz-Neunhoeffer
{"title":"Corrigendum to “Influence of silica fume addition and content on the early hydration of calcium aluminate cement — The role of soluble silicon” [Cem. Concr. Res. 184 (2024) 107618]","authors":"Tillmann Schramm, Jürgen Neubauer, Friedlinde Goetz-Neunhoeffer","doi":"10.1016/j.cemconres.2025.107787","DOIUrl":"10.1016/j.cemconres.2025.107787","url":null,"abstract":"","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"189 ","pages":"Article 107787"},"PeriodicalIF":10.9,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987828","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 : 2025-01-16DOI: 10.1016/j.cemconres.2025.107786
Xianping Liu , Hanqing Gao , Hervé Fryda , Peiming Wang
This study investigates the surface whitening mechanism of ettringite rich decorative mortars. Surface whitening was triggered through an exaggerated test scenario with a highly porous simplified mortar and a series of wet/dry cycles. Based on correlative light-electron microscopy observation, soak solution and mineralogical composition analyses, a mechanism is proposed: surface whitening is due to large agglomerates (>100 μm) of further hydrates (AFt phase and AFm phase) being formed in the large pores of the mortar surface during the drying process. The degree of surface whitening does not follow a continuous increase over cycle numbers, but rather evolves to a maximum after which more cycles lead to reduced surface whitening. This surface clearing and reduced whitening is explained by the disappearance of the hydrate agglomerates caused by full carbonation of AFt phase and AFm phase, transforming to small crystals of CaCO3 and secondary Al(OH)3, releasing the color of the pigments.
{"title":"Surface whitening mechanism of ettringite rich decorative mortar","authors":"Xianping Liu , Hanqing Gao , Hervé Fryda , Peiming Wang","doi":"10.1016/j.cemconres.2025.107786","DOIUrl":"10.1016/j.cemconres.2025.107786","url":null,"abstract":"<div><div>This study investigates the surface whitening mechanism of ettringite rich decorative mortars. Surface whitening was triggered through an exaggerated test scenario with a highly porous simplified mortar and a series of wet/dry cycles. Based on correlative light-electron microscopy observation, soak solution and mineralogical composition analyses, a mechanism is proposed: surface whitening is due to large agglomerates (>100 μm) of further hydrates (AFt phase and AFm phase) being formed in the large pores of the mortar surface during the drying process. The degree of surface whitening does not follow a continuous increase over cycle numbers, but rather evolves to a maximum after which more cycles lead to reduced surface whitening. This surface clearing and reduced whitening is explained by the disappearance of the hydrate agglomerates caused by full carbonation of AFt phase and AFm phase, transforming to small crystals of CaCO<sub>3</sub> and secondary Al(OH)<sub>3</sub>, releasing the color of the pigments.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"189 ","pages":"Article 107786"},"PeriodicalIF":10.9,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987109","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 : 2025-01-10DOI: 10.1016/j.cemconres.2025.107783
Mengyu Zhu , Qingliang Yu , S.R. van der Laan , Yuxuan Chen
Due to absence of C-S-H gel, chemically activated mixed Al-rich steel slag often shows low early-age strength. This work proposes a novel method to accelerate the hydration of Al-rich steel slag by dipotassium hydrogen phosphate (DHP) activation. Results reveal that DHP significantly promotes the formation of layered double hydroxides (LDHs) by increasing pH of the pore solution and supplying phosphate ions as the interlayer anion. Ca-Al-LDHs competes with the used to form metastable C2AH8, thereby releasing additional , which is further accompanied by the increased formation of AH3 gel. Consequently, DHP-activated steel slag develops a denser microstructure dominated by highly-crystalized LDHs and amorphous AH3 gel and achieving impressive compressive strength (40 MPa at 28 days). Overall, this study provides a unique activation method for enhancing the early hydraulic activity of steel slag by in-situ formation of LDHs and AH3 gel, contributing to the unique way to utilize steel-making byproducts.
{"title":"Dipotassium hydrogen phosphate activated Al-rich steel slag: The role of layered double hydroxides and aluminum hydrate gel","authors":"Mengyu Zhu , Qingliang Yu , S.R. van der Laan , Yuxuan Chen","doi":"10.1016/j.cemconres.2025.107783","DOIUrl":"10.1016/j.cemconres.2025.107783","url":null,"abstract":"<div><div>Due to absence of C-S-H gel, chemically activated mixed Al-rich steel slag often shows low early-age strength. This work proposes a novel method to accelerate the hydration of Al-rich steel slag by dipotassium hydrogen phosphate (DHP) activation. Results reveal that DHP significantly promotes the formation of layered double hydroxides (LDHs) by increasing pH of the pore solution and supplying phosphate ions as the interlayer anion. Ca-Al-LDHs competes with the <span><math><msup><mi>Ca</mi><mrow><mn>2</mn><mo>+</mo></mrow></msup></math></span> used to form metastable C<sub>2</sub>AH<sub>8,</sub> thereby releasing additional <span><math><mi>Al</mi><msubsup><mfenced><mi>OH</mi></mfenced><mn>4</mn><mo>−</mo></msubsup></math></span>, which is further accompanied by the increased formation of AH<sub>3</sub> gel. Consequently, DHP-activated steel slag develops a denser microstructure dominated by highly-crystalized LDHs and amorphous AH<sub>3</sub> gel and achieving impressive compressive strength (40 MPa at 28 days). Overall, this study provides a unique activation method for enhancing the early hydraulic activity of steel slag by in-situ formation of LDHs and AH<sub>3</sub> gel, contributing to the unique way to utilize steel-making byproducts.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"189 ","pages":"Article 107783"},"PeriodicalIF":10.9,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142961937","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}
Understanding the hydration of composite binders is essential for decarbonizing the cement industry. This study investigated the microstructure and composition of pastes with either fly ash or slag after different long-term curing. Results show that the elevated temperature slightly reduces the capillary pore volume and internal RH of sealed samples. Water curing largely enhances hydration of fly ash and slag after the first week, forming later-age products in surface zone with stabilized Mc and Hc. This increases both gel and capillary pore volumes. C-A-S-H in water-cured pastes has a longer mean chain length and extremely lower alkali uptake than that in sealed curing. Modelling results indicate that nucleation ceases in sealed pastes once thermodynamic limitations are reached due to self-desiccation. Even with adequate water, late-stage hydration remains kinetically constrained due to the slow nucleation and growth rate near the unhydrated surface, with diffusion likely being one of rate-controlling factors.
{"title":"Effect of curing regimes on composition and microstructure of blended pastes: Insight into later-age hydration mechanism","authors":"Liming Huang , Luping Tang , Zhijun Dong , Birhan Alkadir Abdulahi , Zhenghong Yang","doi":"10.1016/j.cemconres.2025.107785","DOIUrl":"10.1016/j.cemconres.2025.107785","url":null,"abstract":"<div><div>Understanding the hydration of composite binders is essential for decarbonizing the cement industry. This study investigated the microstructure and composition of pastes with either fly ash or slag after different long-term curing. Results show that the elevated temperature slightly reduces the capillary pore volume and internal RH of sealed samples. Water curing largely enhances hydration of fly ash and slag after the first week, forming later-age products in surface zone with stabilized Mc and Hc. This increases both gel and capillary pore volumes. C-A-S-H in water-cured pastes has a longer mean chain length and extremely lower alkali uptake than that in sealed curing. Modelling results indicate that nucleation ceases in sealed pastes once thermodynamic limitations are reached due to self-desiccation. Even with adequate water, late-stage hydration remains kinetically constrained due to the slow nucleation and growth rate near the unhydrated surface, with diffusion likely being one of rate-controlling factors.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"189 ","pages":"Article 107785"},"PeriodicalIF":10.9,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939645","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 : 2025-01-09DOI: 10.1016/j.cemconres.2025.107784
Mateusz Wyrzykowski , Carmelo Di Bella , Davide Sirtoli , Nikolajs Toropovs , Pietro Lura
Concrete made with blended cements with high clinker replacement ratios may be at higher risk of plastic shrinkage cracking when experiencing high evaporation rates immediately after casting. This paper investigates the plastic shrinkage behavior of concretes made with a cement with clinker replacement by a blend of calcined clay and limestone, which was compared to a conventional Portland cement and a Portland-limestone cement. In order to assess the risk of cracking, we studied early deformations and accompanying processes in concretes exposed to fast evaporation in a wind tunnel. As could be expected from previous studies, concretes made with both blended cements experienced higher shrinkage and cracking compared to ordinary Portland cement, mainly due to their slower hydration caused by a lower clinker amount and higher dosage of superplasticizer. However, the extent of plastic shrinkage cracking was similar with calcined-clay limestone cement and Portland-limestone cement.
{"title":"Plastic shrinkage of concrete made with calcined clay-limestone cement","authors":"Mateusz Wyrzykowski , Carmelo Di Bella , Davide Sirtoli , Nikolajs Toropovs , Pietro Lura","doi":"10.1016/j.cemconres.2025.107784","DOIUrl":"10.1016/j.cemconres.2025.107784","url":null,"abstract":"<div><div>Concrete made with blended cements with high clinker replacement ratios may be at higher risk of plastic shrinkage cracking when experiencing high evaporation rates immediately after casting. This paper investigates the plastic shrinkage behavior of concretes made with a cement with clinker replacement by a blend of calcined clay and limestone, which was compared to a conventional Portland cement and a Portland-limestone cement. In order to assess the risk of cracking, we studied early deformations and accompanying processes in concretes exposed to fast evaporation in a wind tunnel. As could be expected from previous studies, concretes made with both blended cements experienced higher shrinkage and cracking compared to ordinary Portland cement, mainly due to their slower hydration caused by a lower clinker amount and higher dosage of superplasticizer. However, the extent of plastic shrinkage cracking was similar with calcined-clay limestone cement and Portland-limestone cement.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"189 ","pages":"Article 107784"},"PeriodicalIF":10.9,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142939633","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 : 2025-01-06DOI: 10.1016/j.cemconres.2024.107780
Prodip Kumar Sarkar , Guido Goracci , Jorge S. Dolado
The energy sector is making a noticeable effort to migrate towards renewable energy to tackle the global warming effect. At large scale, a concentrated solar plant (CSP) is one of the viable options with limitations of steady heat generation due to the uncertainty of sunlight. Thermal batteries can mitigate the trouble to a large extent. Recently, concrete (artificial rock glued by cement) has become a point of interest for the research community as a cheap, nontoxic option. In this paper, thermo-mechanical properties of tricalcium aluminate (CA) have been studied for the first time in the framework of molecular dynamics along with modulated differential scanning calorimetry (MDSC) based experiments. The outcome suggests high-temperature stability of the material with reasonably higher heat capacity and thermal conductivity useful for potential application for thermal battery. Heat transport mechanism at the atomistic level has thoroughly been discussed.
{"title":"Thermal properties of tricalcium aluminate: Molecular dynamics simulation and experimental approach","authors":"Prodip Kumar Sarkar , Guido Goracci , Jorge S. Dolado","doi":"10.1016/j.cemconres.2024.107780","DOIUrl":"10.1016/j.cemconres.2024.107780","url":null,"abstract":"<div><div>The energy sector is making a noticeable effort to migrate towards renewable energy to tackle the global warming effect. At large scale, a concentrated solar plant (CSP) is one of the viable options with limitations of steady heat generation due to the uncertainty of sunlight. Thermal batteries can mitigate the trouble to a large extent. Recently, concrete (artificial rock glued by cement) has become a point of interest for the research community as a cheap, nontoxic option. In this paper, thermo-mechanical properties of tricalcium aluminate (C<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>A) have been studied for the first time in the framework of molecular dynamics along with modulated differential scanning calorimetry (MDSC) based experiments. The outcome suggests high-temperature stability of the material with reasonably higher heat capacity and thermal conductivity useful for potential application for thermal battery. Heat transport mechanism at the atomistic level has thoroughly been discussed.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"189 ","pages":"Article 107780"},"PeriodicalIF":10.9,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935160","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 : 2025-01-04DOI: 10.1016/j.cemconres.2024.107781
Zhe Zhang, Yuchen Hu, Lianyao Xiong, Guoqing Geng
C-S-H is the primary binder in cement mixed with additional phases. It is essential to understand how different phases impact cement strength. This study presents an innovative method for preparing a binary system doped with C-S-H and additional phases to study the effects of these phases on the composite's strength. By blending C-S-H with various minerals, we control mineral content precisely. Using multiscale techniques including atomic force microscopy (AFM), hardness and modulus measurements, we quantify the effects of minerals on C-S-H composites. Findings reveal the intrinsic moduli of these phases significantly influence composites' hardness, while cohesion affect compression modulus. Notably, quartz has a higher intrinsic modulus but lower cohesion than C-S-H, resulting in larger hardness but lower compression modulus. Ettringite shows reduced hardness and compression modulus, while calcite and portlandite's effects remain ambiguous due to lower cohesion but larger intrinsic modulus. These insights offer pathways for enhancing cementitious composites' performance.
{"title":"The influence of portlandite, calcite, quartz and ettringite inclusions on the multiscale mechanical behaviors of C-S-H matrix","authors":"Zhe Zhang, Yuchen Hu, Lianyao Xiong, Guoqing Geng","doi":"10.1016/j.cemconres.2024.107781","DOIUrl":"10.1016/j.cemconres.2024.107781","url":null,"abstract":"<div><div>C-S-H is the primary binder in cement mixed with additional phases. It is essential to understand how different phases impact cement strength. This study presents an innovative method for preparing a binary system doped with C-S-H and additional phases to study the effects of these phases on the composite's strength. By blending C-S-H with various minerals, we control mineral content precisely. Using multiscale techniques including atomic force microscopy (AFM), hardness and modulus measurements, we quantify the effects of minerals on C-S-H composites. Findings reveal the intrinsic moduli of these phases significantly influence composites' hardness, while cohesion affect compression modulus. Notably, quartz has a higher intrinsic modulus but lower cohesion than C-S-H, resulting in larger hardness but lower compression modulus. Ettringite shows reduced hardness and compression modulus, while calcite and portlandite's effects remain ambiguous due to lower cohesion but larger intrinsic modulus. These insights offer pathways for enhancing cementitious composites' performance.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"189 ","pages":"Article 107781"},"PeriodicalIF":10.9,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924777","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 : 2024-12-31DOI: 10.1016/j.cemconres.2024.107660
Yong Tao , Pablo Martin , Hegoi Manzano , Mohammad Javad Abdolhosseini Qomi
Dicalcium silicate dissolution is crucial in cement hydration and provides long-term durability. However, our understanding of its dissolution process is limited due to its multiscale nature. To resolve this limitation, we combine rare event molecular dynamics and kinetic Monte Carlo (KMC) techniques. At the nanoscale, we reveal the relationship between surface Ca2＋ coordination chemistry and dissolution free energy barriers. Leveraging this knowledge, KMC simulations accurately predict the apparent dissolution activation energy and the sigmoidal relationship between dissolution rate and solution activity observed in experiments. Importantly, we find that dislocations have minimal impact on dissolution rates in grains and fast-dissolving cleavages. Instead, these rates are primarily determined by spontaneous pit opening and coalescence on surfaces, and the receding corners and edges within dissolving grains. This multiscale framework paves the path for fundamental studies and quantitative prediction of dissolution–precipitation processes widely encountered in cement chemistry, carbon sequestration, and enhanced geothermal systems.
{"title":"Mesoscopic mechanisms of dicalcium silicate dissolution","authors":"Yong Tao , Pablo Martin , Hegoi Manzano , Mohammad Javad Abdolhosseini Qomi","doi":"10.1016/j.cemconres.2024.107660","DOIUrl":"10.1016/j.cemconres.2024.107660","url":null,"abstract":"<div><div>Dicalcium silicate dissolution is crucial in cement hydration and provides long-term durability. However, our understanding of its dissolution process is limited due to its multiscale nature. To resolve this limitation, we combine rare event molecular dynamics and kinetic Monte Carlo (KMC) techniques. At the nanoscale, we reveal the relationship between surface Ca<sup>2＋</sup> coordination chemistry and dissolution free energy barriers. Leveraging this knowledge, KMC simulations accurately predict the apparent dissolution activation energy and the sigmoidal relationship between dissolution rate and solution activity observed in experiments. Importantly, we find that dislocations have minimal impact on dissolution rates in grains and fast-dissolving cleavages. Instead, these rates are primarily determined by spontaneous pit opening and coalescence on surfaces, and the receding corners and edges within dissolving grains. This multiscale framework paves the path for fundamental studies and quantitative prediction of dissolution–precipitation processes widely encountered in cement chemistry, carbon sequestration, and enhanced geothermal systems.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"189 ","pages":"Article 107660"},"PeriodicalIF":10.9,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142904752","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 : 2024-12-31DOI: 10.1016/j.cemconres.2024.107707
Yiyuan Zhang , Yaxin Tao , Jose R.A. Godinho , Kim Van Tittelboom , Karel Lesage , Geert De Schutter
This study aims to achieve active rheology control of cementitious materials from the new view of magneto-responsive aggregates. It provides a sound experimental validation, qualitative analysis and quantitative characterization of magnetorheological response and mechanism of cementitious materials containing responsive aggregates under a nozzle/pipe-like (inline) external magnetic field. Specially, the aggregate shape indicators, rheological responses and micro-/meso- structures are described. The physical, chemical and geometrical features of aggregates were determined by X-ray diffraction analysis (XRD), vibrating sample magnetometer (VSM), loose packing fraction, optical microscopy and X-ray computed tomography (CT). The slow penetration test and vane test were conducted to measure the structural build-up of fresh samples with and without an inline magnetic intervention by using a rheometer-based customized test setup. The spatial distribution of magneto-responsive aggregates was determined by employing X-ray CT. The internal skeletal contact properties of magneto-responsive aggregates including cluster orientation, cluster aspect ratio, cluster elongation, contact point number, contact length and contact area were characterized quantitatively from the 3D image. A newly developed magneto-responsive cement mortar which can adjust rheological properties in time and on demand was achieved. The alignments of magneto-responsive aggregates along the magnetic induction lines were visualized. The orientation of magneto-responsive aggregate clusters showed concentrated distribution. With the decrease of the cement-to-aggregate ratio and increase in the size of magneto-responsive aggregates, the field-induced yield stress and torque increased significantly, which also influenced the contact properties of magneto-responsive aggregates. These results are beneficial for the application of active rheology control of magneto-responsive cementitious materials.
{"title":"Active rheology control of cementitious materials: New insights from magneto-responsive aggregates","authors":"Yiyuan Zhang , Yaxin Tao , Jose R.A. Godinho , Kim Van Tittelboom , Karel Lesage , Geert De Schutter","doi":"10.1016/j.cemconres.2024.107707","DOIUrl":"10.1016/j.cemconres.2024.107707","url":null,"abstract":"<div><div>This study aims to achieve active rheology control of cementitious materials from the new view of magneto-responsive aggregates. It provides a sound experimental validation, qualitative analysis and quantitative characterization of magnetorheological response and mechanism of cementitious materials containing responsive aggregates under a nozzle/pipe-like (inline) external magnetic field. Specially, the aggregate shape indicators, rheological responses and micro-/meso- structures are described. The physical, chemical and geometrical features of aggregates were determined by X-ray diffraction analysis (XRD), vibrating sample magnetometer (VSM), loose packing fraction, optical microscopy and X-ray computed tomography (CT). The slow penetration test and vane test were conducted to measure the structural build-up of fresh samples with and without an inline magnetic intervention by using a rheometer-based customized test setup. The spatial distribution of magneto-responsive aggregates was determined by employing X-ray CT. The internal skeletal contact properties of magneto-responsive aggregates including cluster orientation, cluster aspect ratio, cluster elongation, contact point number, contact length and contact area were characterized quantitatively from the 3D image. A newly developed magneto-responsive cement mortar which can adjust rheological properties in time and on demand was achieved. The alignments of magneto-responsive aggregates along the magnetic induction lines were visualized. The orientation of magneto-responsive aggregate clusters showed concentrated distribution. With the decrease of the cement-to-aggregate ratio and increase in the size of magneto-responsive aggregates, the field-induced yield stress and torque increased significantly, which also influenced the contact properties of magneto-responsive aggregates. These results are beneficial for the application of active rheology control of magneto-responsive cementitious materials.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"189 ","pages":"Article 107707"},"PeriodicalIF":10.9,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142904751","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 investigated semi-dry carbonation at different relative humidities (RH) under atmospheric CO2 concentrations to determine the effect of RH on the degree of carbonation (DoC) and reaction rates. The carbonation kinetics of each calcium-containing hydrate exhibited an initial rapid chemical-reaction-limited stage, followed by a significantly slower stage. DoC values plateaued after 200 days of carbonation, reaching 78 % at 95 % RH and 34 % at 33 % RH, aligning with EN 16757 values for sheltered outdoor and indoor environments, respectively. When the samples reached a stable DoC at a given RH, further carbonation occurred upon exposure to higher RH, implying that the DoC was governed by the highest RH to which the samples had been exposed. The phase assemblage was also affected, approaching thermodynamic equilibrium at higher RH but deviating at lower RH due to the formation of local equilibria and the presence of metastable phases.
{"title":"Semi-dry natural carbonation at different relative humidities: Degree of carbonation and reaction kinetics of calcium hydrates in cement paste","authors":"Naohiko Saeki , Ryo Kurihara , Takahiro Ohkubo , Atsushi Teramoto , Yuya Suda , Ryoma Kitagaki , Ippei Maruyama","doi":"10.1016/j.cemconres.2024.107777","DOIUrl":"10.1016/j.cemconres.2024.107777","url":null,"abstract":"<div><div>This study investigated semi-dry carbonation at different relative humidities (RH) under atmospheric CO<sub>2</sub> concentrations to determine the effect of RH on the degree of carbonation (DoC) and reaction rates. The carbonation kinetics of each calcium-containing hydrate exhibited an initial rapid chemical-reaction-limited stage, followed by a significantly slower stage. DoC values plateaued after 200 days of carbonation, reaching 78 % at 95 % RH and 34 % at 33 % RH, aligning with EN 16757 values for sheltered outdoor and indoor environments, respectively. When the samples reached a stable DoC at a given RH, further carbonation occurred upon exposure to higher RH, implying that the DoC was governed by the highest RH to which the samples had been exposed. The phase assemblage was also affected, approaching thermodynamic equilibrium at higher RH but deviating at lower RH due to the formation of local equilibria and the presence of metastable phases.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"189 ","pages":"Article 107777"},"PeriodicalIF":10.9,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142902104","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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