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":"https://doi.org/10.1016/j.cemconres.2025.107784","url":null,"abstract":"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.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"82 1","pages":""},"PeriodicalIF":11.4,"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":"","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":"https://doi.org/10.1016/j.cemconres.2024.107780","url":null,"abstract":"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><span style=\"\"></span><span data-mathml='<math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub is=\"true\"><mrow is=\"true\" /><mrow is=\"true\"><mn is=\"true\">3</mn></mrow></msub></math>' role=\"presentation\" style=\"font-size: 90%; display: inline-block; position: relative;\" tabindex=\"0\"><svg aria-hidden=\"true\" focusable=\"false\" height=\"1.509ex\" role=\"img\" style=\"vertical-align: -0.582ex;\" viewbox=\"0 -399.4 453.9 649.8\" width=\"1.054ex\" xmlns:xlink=\"http://www.w3.org/1999/xlink\"><g fill=\"currentColor\" stroke=\"currentColor\" stroke-width=\"0\" transform=\"matrix(1 0 0 -1 0 0)\"><g is=\"true\"><g is=\"true\"></g><g is=\"true\" transform=\"translate(0,-150)\"><g is=\"true\"><use transform=\"scale(0.707)\" xlink:href=\"#MJMAIN-33\"></use></g></g></g></g></svg><span role=\"presentation\"><math xmlns=\"http://www.w3.org/1998/Math/MathML\"><msub is=\"true\"><mrow is=\"true\"></mrow><mrow is=\"true\"><mn is=\"true\">3</mn></mrow></msub></math></span></span><script type=\"math/mml\"><math><msub is=\"true\"><mrow is=\"true\"></mrow><mrow is=\"true\"><mn is=\"true\">3</mn></mrow></msub></math></script></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.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"1 1","pages":""},"PeriodicalIF":11.4,"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":"","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":"https://doi.org/10.1016/j.cemconres.2024.107781","url":null,"abstract":"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.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"20 1","pages":""},"PeriodicalIF":11.4,"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":"https://doi.org/10.1016/j.cemconres.2024.107660","url":null,"abstract":"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.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"13 1","pages":""},"PeriodicalIF":11.4,"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":"","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":"https://doi.org/10.1016/j.cemconres.2024.107707","url":null,"abstract":"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.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"325 1","pages":""},"PeriodicalIF":11.4,"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":"https://doi.org/10.1016/j.cemconres.2024.107777","url":null,"abstract":"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.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"35 1","pages":""},"PeriodicalIF":11.4,"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":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-12-30DOI: 10.1016/j.cemconres.2024.107776
Jihoon Park, Joonho Seo, Solmoi Park, Alam Cho, H.K. Lee
The present study investigated the effect of CO2 concentration during carbonation curing on the microstructural evolution of calcium sulfoaluminate (CSA) cement. Carbonation curing was performed for 28 d at 3 % and 10 % CO2 concentrations. To profile the microstructure, samples were collected from the surface of the cement to a depth of 30 mm on set curing days. At 3 % CO2 concentration, vaterite and aragonite predominated, and calcite was generated from the recrystallization of vaterite. At 10 % CO2 concentration, the formation of aragonite was mainly observed, with distinct phase transition from vaterite to aragonite during curing. The delayed CO2 penetration rate with an increasing depth from the surface led to an increase in the content of calcite and aragonite at 3 % and 10 % CO2 concentrations, respectively. The phase assemblages of carbonation-cured CSA cement were thermodynamically predicted and compared with the experimental data to elucidate the microstructural evolution beyond the testing timeframe.
{"title":"Phase profiling of carbonation-cured calcium sulfoaluminate cement","authors":"Jihoon Park, Joonho Seo, Solmoi Park, Alam Cho, H.K. Lee","doi":"10.1016/j.cemconres.2024.107776","DOIUrl":"https://doi.org/10.1016/j.cemconres.2024.107776","url":null,"abstract":"The present study investigated the effect of CO<sub>2</sub> concentration during carbonation curing on the microstructural evolution of calcium sulfoaluminate (CSA) cement. Carbonation curing was performed for 28 d at 3 % and 10 % CO<sub>2</sub> concentrations. To profile the microstructure, samples were collected from the surface of the cement to a depth of 30 mm on set curing days. At 3 % CO<sub>2</sub> concentration, vaterite and aragonite predominated, and calcite was generated from the recrystallization of vaterite. At 10 % CO<sub>2</sub> concentration, the formation of aragonite was mainly observed, with distinct phase transition from vaterite to aragonite during curing. The delayed CO<sub>2</sub> penetration rate with an increasing depth from the surface led to an increase in the content of calcite and aragonite at 3 % and 10 % CO<sub>2</sub> concentrations, respectively. The phase assemblages of carbonation-cured CSA cement were thermodynamically predicted and compared with the experimental data to elucidate the microstructural evolution beyond the testing timeframe.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"5 1","pages":""},"PeriodicalIF":11.4,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142901917","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 : 2024-12-29DOI: 10.1016/j.cemconres.2024.107779
Jiwei Jia, Ali Zaoui, W. Sekkal
Using polymer binders in cementitious materials significantly boosts their structural stability and durability for civil engineering applications. This study explored the role of polymeric binders in enhancing the morphological stability of calcium silicate hydrates (CSH) paste through molecular dynamics simulations. Most pure CSH configurations displayed larger voids and decreased stability, especially when the particles were initially spaced further apart. Among the tested polymers, polyvinyl alcohol (PVA) showed the most robust bonding to CSH, attributed to its abundant -OH groups. The integration of polymers led to a shift in aggregation toward a more stable face-to-face (FF) configuration, increasing the contact area, and boosting overall stability. At large distances, the Coulombic force acted aggregation in the initial phase but is soon overtaken by the vdW force, which plays the primary role in driving the aggregation process. These findings corroborate existing theoretical models and introduce fresh insights from experimental organic-inorganic interactions, providing substantial implications for the development of advanced cementitious composites.
{"title":"Impact of polymer binders on the aggregation modes of two-pieces CSH composites","authors":"Jiwei Jia, Ali Zaoui, W. Sekkal","doi":"10.1016/j.cemconres.2024.107779","DOIUrl":"https://doi.org/10.1016/j.cemconres.2024.107779","url":null,"abstract":"Using polymer binders in cementitious materials significantly boosts their structural stability and durability for civil engineering applications. This study explored the role of polymeric binders in enhancing the morphological stability of calcium silicate hydrates (CSH) paste through molecular dynamics simulations. Most pure CSH configurations displayed larger voids and decreased stability, especially when the particles were initially spaced further apart. Among the tested polymers, polyvinyl alcohol (PVA) showed the most robust bonding to CSH, attributed to its abundant -OH groups. The integration of polymers led to a shift in aggregation toward a more stable face-to-face (F<img alt=\"single bond\" src=\"https://sdfestaticassets-us-east-1.sciencedirectassets.com/shared-assets/55/entities/sbnd.gif\" style=\"vertical-align:middle\"/>F) configuration, increasing the contact area, and boosting overall stability. At large distances, the Coulombic force acted aggregation in the initial phase but is soon overtaken by the vdW force, which plays the primary role in driving the aggregation process. These findings corroborate existing theoretical models and introduce fresh insights from experimental organic-inorganic interactions, providing substantial implications for the development of advanced cementitious composites.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"14 1","pages":""},"PeriodicalIF":11.4,"publicationDate":"2024-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888270","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 : 2024-12-29DOI: 10.1016/j.cemconres.2024.107778
Andreas Leemann
In the discussed study, synthesized ASR products of unknown internal relative humidity (RH) were brought into contact with water using the osmotic cell test. They were not conditioned to an identical RH corresponding to the one of ASR affected concrete before the test. Moreover, swelling and osmotic pressure depend on the difference in the ionic concentration between two solutions. ASR products formed in reactive concrete aggregates are only exposed to the pore solution of the concrete and not to water. Using water in an osmotic cell test leads to results that are not representative for ASR in concrete.
{"title":"Discussion of the paper “Effect of the chemical composition of synthetic alkali-silica gels on their structure, swelling behavior and water uptake” by Miriam E. Krüger, Harald Hilbig, Ludwig Stelzner and Alisa Machner, Cem. Conc. Res. 184 (2024): 107596","authors":"Andreas Leemann","doi":"10.1016/j.cemconres.2024.107778","DOIUrl":"https://doi.org/10.1016/j.cemconres.2024.107778","url":null,"abstract":"In the discussed study, synthesized ASR products of unknown internal relative humidity (RH) were brought into contact with water using the osmotic cell test. They were not conditioned to an identical RH corresponding to the one of ASR affected concrete before the test. Moreover, swelling and osmotic pressure depend on the difference in the ionic concentration between two solutions. ASR products formed in reactive concrete aggregates are only exposed to the pore solution of the concrete and not to water. Using water in an osmotic cell test leads to results that are not representative for ASR in concrete.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"19 1","pages":""},"PeriodicalIF":11.4,"publicationDate":"2024-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142888073","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 : 2024-12-24DOI: 10.1016/j.cemconres.2024.107775
Rotana Hay, Parham Aghdasi
This study investigates the physico-chemical change in a Type IL cement prehydrated in the natural environment for 7, 14, and 21 days. A focus was made on the reaction kinetics, product formation, and strength development using calorimetry, XRF, QXRD, TGA and compressive testing. It was found that prehydration converted hemihydrate to gypsum and partially transformed the principal cement phases and inherent portlandite into carbonates, thus reducing C3S and C2S while increasing CaCO3 and gypsum. Hydration was slowed down with a delay in the appearance of the aluminate peak and reduction in cumulative heat at 72 h. Consequently, more C3S and C2S remained at an early age. Less ettringite was formed while amorphous phases were initially reduced but promoted later on. A secondary decomposition peak linked to metastable CaCO3 became more prominent in the prehydrated samples. The early-age strength was reduced with the exposure time, but the 28-day strength improved due to the continuing hydration.
{"title":"Effects of environmental exposure on Portland cement Type IL","authors":"Rotana Hay, Parham Aghdasi","doi":"10.1016/j.cemconres.2024.107775","DOIUrl":"https://doi.org/10.1016/j.cemconres.2024.107775","url":null,"abstract":"This study investigates the physico-chemical change in a Type IL cement prehydrated in the natural environment for 7, 14, and 21 days. A focus was made on the reaction kinetics, product formation, and strength development using calorimetry, XRF, QXRD, TGA and compressive testing. It was found that prehydration converted hemihydrate to gypsum and partially transformed the principal cement phases and inherent portlandite into carbonates, thus reducing C<sub>3</sub>S and C<sub>2</sub>S while increasing CaCO<sub>3</sub> and gypsum. Hydration was slowed down with a delay in the appearance of the aluminate peak and reduction in cumulative heat at 72 h. Consequently, more C<sub>3</sub>S and C<sub>2</sub>S remained at an early age. Less ettringite was formed while amorphous phases were initially reduced but promoted later on. A secondary decomposition peak linked to metastable CaCO<sub>3</sub> became more prominent in the prehydrated samples. The early-age strength was reduced with the exposure time, but the 28-day strength improved due to the continuing hydration.","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"41 1","pages":""},"PeriodicalIF":11.4,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142884323","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}
F) configuration, increasing the contact area, and boosting overall stability. At large distances, the Coulombic force acted aggregation in the initial phase but is soon overtaken by the vdW force, which plays the primary role in driving the aggregation process. These findings corroborate existing theoretical models and introduce fresh insights from experimental organic-inorganic interactions, providing substantial implications for the development of advanced cementitious composites.
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