This study investigates the influence of CO2 concentration on the carbonation process in cementitious paste, focusing on water content distribution in ordinary Portlandite cement and limestone-calcined clay cement (LC3). Employing single-sided nuclear magnetic resonance spectroscopy for water profiling, we revealed that under accelerated carbonation of 5 % and 1 %, the water content in fine pores (interlayer space and gel pores) kept constant at the carbonation front, demonstrating the plugging effect where fine pore water removal governs carbonation progress. This effect was absent under natural carbonation conditions because evaporation precedes the carbonation process. This study emphasizes that to accurately characterize cementitious materials under natural carbonation conditions, CO2 concentrations in accelerated methods should be constrained to prevent the plugging effect.
{"title":"Plugging effect of fine pore water in OPC and LC3 paste during accelerated carbonation monitored via single-sided nuclear magnetic resonance spectroscopy","authors":"Luge Cheng , Ryo Kurihara , Takahiro Ohkubo , Ryoma Kitagaki , Atsushi Teramoto , Yuya Suda , Ippei Maruyama","doi":"10.1016/j.cemconres.2024.107688","DOIUrl":"10.1016/j.cemconres.2024.107688","url":null,"abstract":"<div><div>This study investigates the influence of CO<sub>2</sub> concentration on the carbonation process in cementitious paste, focusing on water content distribution in ordinary Portlandite cement and limestone-calcined clay cement (LC<sup>3</sup>). Employing single-sided nuclear magnetic resonance spectroscopy for water profiling, we revealed that under accelerated carbonation of 5 % and 1 %, the water content in fine pores (interlayer space and gel pores) kept constant at the carbonation front, demonstrating the <em>plugging effect</em> where fine pore water removal governs carbonation progress. This effect was absent under natural carbonation conditions because evaporation precedes the carbonation process. This study emphasizes that to accurately characterize cementitious materials under natural carbonation conditions, CO<sub>2</sub> concentrations in accelerated methods should be constrained to prevent the plugging effect.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"186 ","pages":"Article 107688"},"PeriodicalIF":10.9,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142384416","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 : 2024-10-08DOI: 10.1016/j.cemconres.2024.107691
Han Gao , Igor Shikhov , Ehab Hamed , Ailar Hajimohammadi , Iman Al-Damad , Christoph Arns , Stephen J. Foster
In this paper, basic creep mechanism of ambient cured one-part alkali activated slag-fly ash (AASF) paste is examined at the microscopic level. A special mini creep rig is constructed enabling in-situ monitoring of water redistribution over time between high- and low-density (HD, LD) gel pores within the loaded paste specimens using 1H NMR relaxometry. The results suggest that the contraction of C-(N)-A-S-H particles is accompanied by the reduction of water content in HD gel for loaded AASF paste. In contrast, in the loaded OPC paste a noticeable decrease of water residing in LD rather than HD C-S-H gel was observed, implying the presence of a distinct creep mechanism. In addition to the different water environment, the more crosslinked bonding structure of AASF could partially account for its lower creep response supported by 29Si NMR measurement. The findings of this study provide evidence in understanding underlying basic creep mechanism of AASF.
{"title":"New insights on the basic creep mechanism of one-part alkali activated slag and fly ash paste","authors":"Han Gao , Igor Shikhov , Ehab Hamed , Ailar Hajimohammadi , Iman Al-Damad , Christoph Arns , Stephen J. Foster","doi":"10.1016/j.cemconres.2024.107691","DOIUrl":"10.1016/j.cemconres.2024.107691","url":null,"abstract":"<div><div>In this paper, basic creep mechanism of ambient cured one-part alkali activated slag-fly ash (AASF) paste is examined at the microscopic level. A special mini creep rig is constructed enabling in-situ monitoring of water redistribution over time between high- and low-density (HD, LD) gel pores within the loaded paste specimens using <sup>1</sup>H NMR relaxometry. The results suggest that the contraction of C-(N)-A-S-H particles is accompanied by the reduction of water content in HD gel for loaded AASF paste. In contrast, in the loaded OPC paste a noticeable decrease of water residing in LD rather than HD C-S-H gel was observed, implying the presence of a distinct creep mechanism. In addition to the different water environment, the more crosslinked bonding structure of AASF could partially account for its lower creep response supported by <sup>29</sup>Si NMR measurement. The findings of this study provide evidence in understanding underlying basic creep mechanism of AASF.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"186 ","pages":"Article 107691"},"PeriodicalIF":10.9,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142384423","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 : 2024-10-02DOI: 10.1016/j.cemconres.2024.107690
Weihuan Li , Chenchen Xiong , Yang Zhou , Wentao Chen , Yangzezhi Zheng , Wei Lin , Jiarui Xing
The molecular-scale mechanical properties of calcium silicate hydrates are crucial to the macro performance of cementitious materials, while achieving coincidence between accuracy and efficiency in computational simulations still remains a challenge. This study utilizes a deep-learning potential, specifically developed for calcium silicate hydrates based on artificial neural network, to achieve molecular dynamics simulations with accuracy comparable to first-principle methods. With this potential, the elastic properties and uniaxial mechanical behaviors are explored, wherein the anisotropy and impact mechanism of calcium ratios are analyzed. The results add to evidence that the deep-learning potential possess a higher accuracy than common force fields. The anisotropy of elastic modulus is mainly attributed to different atomic interactions in various directions, while the anisotropy of strength is additionally affected by the form of failure. This study may advance the accurate molecular-scale simulation and deepen the understanding of the strength source and cohesion mechanism of cement-based materials.
{"title":"Insights on the mechanical properties and failure mechanisms of calcium silicate hydrates based on deep-learning potential molecular dynamics","authors":"Weihuan Li , Chenchen Xiong , Yang Zhou , Wentao Chen , Yangzezhi Zheng , Wei Lin , Jiarui Xing","doi":"10.1016/j.cemconres.2024.107690","DOIUrl":"10.1016/j.cemconres.2024.107690","url":null,"abstract":"<div><div>The molecular-scale mechanical properties of calcium silicate hydrates are crucial to the macro performance of cementitious materials, while achieving coincidence between accuracy and efficiency in computational simulations still remains a challenge. This study utilizes a deep-learning potential, specifically developed for calcium silicate hydrates based on artificial neural network, to achieve molecular dynamics simulations with accuracy comparable to first-principle methods. With this potential, the elastic properties and uniaxial mechanical behaviors are explored, wherein the anisotropy and impact mechanism of calcium ratios are analyzed. The results add to evidence that the deep-learning potential possess a higher accuracy than common force fields. The anisotropy of elastic modulus is mainly attributed to different atomic interactions in various directions, while the anisotropy of strength is additionally affected by the form of failure. This study may advance the accurate molecular-scale simulation and deepen the understanding of the strength source and cohesion mechanism of cement-based materials.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"186 ","pages":"Article 107690"},"PeriodicalIF":10.9,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369632","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 : 2024-10-02DOI: 10.1016/j.cemconres.2024.107686
Guitao Luo , Muyu Liu , Hua Li , Yang Liu , Hongbo Tan , Qimin Liu
Adsorption effect on particle surfaces and complexation effect with free Ca2+ mostly determine the retarding performance of organic admixtures on cement hydration. However, it is difficult to identify which effect plays a more important role in retarding hydration by experimental methods. Here, a theoretical model was developed to investigate the retarding mechanisms of sodium gluconate (SG) on hydration of tricalcium silicate (C3S). Based on obstruction theory and complexation reaction kinetics, effects of adsorption and complexation were simulated to examine the retarding performance of C3S hydration with addition of SG. The proposed model well predicted the effect of additional dosing of SG on the retarding performance of C3S hydration. Theoretical parameter studies demonstrated that adsorption ratio contributed much largely to the delays in C3S hydration, compared with rate constant of complex generation. Therefore, it is confirmed that adsorption plays a more important role in regulating the retarding mechanism of C3S hydration.
{"title":"Importance of adsorption compared with complexation for retarding C3S hydration via adding sodium gluconate","authors":"Guitao Luo , Muyu Liu , Hua Li , Yang Liu , Hongbo Tan , Qimin Liu","doi":"10.1016/j.cemconres.2024.107686","DOIUrl":"10.1016/j.cemconres.2024.107686","url":null,"abstract":"<div><div>Adsorption effect on particle surfaces and complexation effect with free Ca<sup>2+</sup> mostly determine the retarding performance of organic admixtures on cement hydration. However, it is difficult to identify which effect plays a more important role in retarding hydration by experimental methods. Here, a theoretical model was developed to investigate the retarding mechanisms of sodium gluconate (SG) on hydration of tricalcium silicate (C<sub>3</sub>S). Based on obstruction theory and complexation reaction kinetics, effects of adsorption and complexation were simulated to examine the retarding performance of C<sub>3</sub>S hydration with addition of SG. The proposed model well predicted the effect of additional dosing of SG on the retarding performance of C<sub>3</sub>S hydration. Theoretical parameter studies demonstrated that adsorption ratio contributed much largely to the delays in C<sub>3</sub>S hydration, compared with rate constant of complex generation. Therefore, it is confirmed that adsorption plays a more important role in regulating the retarding mechanism of C<sub>3</sub>S hydration.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"186 ","pages":"Article 107686"},"PeriodicalIF":10.9,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142369637","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 : 2024-09-28DOI: 10.1016/j.cemconres.2024.107685
Hela Bessaies-Bey , Xiaohan Yu , Wenqiang Zuo , Oumayma Ahmadah , Janine Deou , Laura Caneda-Martínez , Nicolas Roussel
This paper introduces three major recommendations for the assessment of the maximum packing fraction of mineral powders through compressive rheology. First, our results show that a minimum compressive stress is required for the measured solid volume fraction to tend towards a constant jamming fraction. Second, we show that the modification of the particles surface properties, especially their friction coefficient, by polymer adsorption, allows for this jamming fraction to get closer to the particle maximum packing fraction. Finally, we show that a minimal value of the initial solid volume fraction of a sample is necessary to prevent particle size separation during testing. We moreover show that the measured jamming fraction depends on the initial solid volume fraction of cement-based samples. We suggest that such a peculiar behavior finds its origin in the dependency of early hydrates volume or morphology on the initial supersaturation.
{"title":"Packing properties assessment of cement and alternative powders: Artefacts and protocols","authors":"Hela Bessaies-Bey , Xiaohan Yu , Wenqiang Zuo , Oumayma Ahmadah , Janine Deou , Laura Caneda-Martínez , Nicolas Roussel","doi":"10.1016/j.cemconres.2024.107685","DOIUrl":"10.1016/j.cemconres.2024.107685","url":null,"abstract":"<div><div>This paper introduces three major recommendations for the assessment of the maximum packing fraction of mineral powders through compressive rheology. First, our results show that a minimum compressive stress is required for the measured solid volume fraction to tend towards a constant jamming fraction. Second, we show that the modification of the particles surface properties, especially their friction coefficient, by polymer adsorption, allows for this jamming fraction to get closer to the particle maximum packing fraction. Finally, we show that a minimal value of the initial solid volume fraction of a sample is necessary to prevent particle size separation during testing. We moreover show that the measured jamming fraction depends on the initial solid volume fraction of cement-based samples. We suggest that such a peculiar behavior finds its origin in the dependency of early hydrates volume or morphology on the initial supersaturation.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"186 ","pages":"Article 107685"},"PeriodicalIF":10.9,"publicationDate":"2024-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142325876","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 : 2024-09-26DOI: 10.1016/j.cemconres.2024.107687
Rachid Cherif , Carmen Andrade , Abdelkarim Aït-Mokhtar
In this paper, multi-ion transference numbers were determined throughout the chloride migration testing of low clinker cement-based materials. For this purpose, five cement pastes were studied: pure Portland paste (as a reference) and four other pastes, based on limestone filler, fly ash, slag or silica fume. The transference numbers were calculated from the concentration evolution in the three zones of the migration cell (catholyte, anolyte and sample), considering that: (i) ions moved in the catholyte and anolyte; (ii) ions leached from the sample; (iii) ions were generated from the electrode processes, and (iv) the pore solution of the sample evolved during the test. The chloride transference numbers of pastes with pure Portland cement, limestone filler, fly ash, slag or silica fume are almost zero at the beginning of the migration test but 0.23; 0.18; 0.06; 0.05 and 0.20 at the end of the test, respectively. The ion transference numbers obtained were used for the calculation of diffusion coefficients of chlorides, sodium and potassium using the Nernst-Einstein equation.
{"title":"Experimental investigation of the impact of additives in low clinker cementitious materials on multi-ion transference numbers and diffusion coefficients","authors":"Rachid Cherif , Carmen Andrade , Abdelkarim Aït-Mokhtar","doi":"10.1016/j.cemconres.2024.107687","DOIUrl":"10.1016/j.cemconres.2024.107687","url":null,"abstract":"<div><div>In this paper, multi-ion transference numbers were determined throughout the chloride migration testing of low clinker cement-based materials. For this purpose, five cement pastes were studied: pure Portland paste (as a reference) and four other pastes, based on limestone filler, fly ash, slag or silica fume. The transference numbers were calculated from the concentration evolution in the three zones of the migration cell (catholyte, anolyte and sample), considering that: (i) ions moved in the catholyte and anolyte; (ii) ions leached from the sample; (iii) ions were generated from the electrode processes, and (iv) the pore solution of the sample evolved during the test. The chloride transference numbers of pastes with pure Portland cement, limestone filler, fly ash, slag or silica fume are almost zero at the beginning of the migration test but 0.23; 0.18; 0.06; 0.05 and 0.20 at the end of the test, respectively. The ion transference numbers obtained were used for the calculation of diffusion coefficients of chlorides, sodium and potassium using the Nernst-Einstein equation.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"186 ","pages":"Article 107687"},"PeriodicalIF":10.9,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322770","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 : 2024-09-25DOI: 10.1016/j.cemconres.2024.107673
Rongwei Yang , Shan He , Junyao Liu , Jiyun Shen , Linlin Wang , Yongjin Yu , Dongwei Hou
Understanding the tensile strength and failure mechanism of rock–cement interfacial transition zone (ITZ) is of vital significance to the sealing integrity of cement sheath under downhole condition. Taking advantage of multiple techniques, i.e., digital image correlation (DIC), nano-indentation, XRD-Rietveld analysis, MAS solid NMR, and SEM-EDX, this study is devoted to investigating the impacts of curing temperature, rock type, and the addition of nano-silica (NS), on the tensile strength and failure mechanism of rock–cement sample. The experimental results show that both the curing temperature and the addition of NS leads to the formation of more C-S-H, which densifies the ITZ microstructure and responsible for high tensile strength of rock–cement samples; the tensile strengths of shale-cement samples are consistently higher than those of sandstone-cement sample; the crack velocities for rock–cement samples under three-point bending tests are approximately 1 mm/s, the crack velocities for rock–cement samples are slowed down when the NS is incorporated in cement paste, but they are independent on the rock type and curing temperature.
{"title":"Tensile strength and failure mechanism of rock–cement sample: Roles of curing temperature, nano-silica and rock type","authors":"Rongwei Yang , Shan He , Junyao Liu , Jiyun Shen , Linlin Wang , Yongjin Yu , Dongwei Hou","doi":"10.1016/j.cemconres.2024.107673","DOIUrl":"10.1016/j.cemconres.2024.107673","url":null,"abstract":"<div><div>Understanding the tensile strength and failure mechanism of rock–cement interfacial transition zone (ITZ) is of vital significance to the sealing integrity of cement sheath under downhole condition. Taking advantage of multiple techniques, i.e., digital image correlation (DIC), nano-indentation, XRD-Rietveld analysis, <span><math><mrow><msup><mrow></mrow><mrow><mn>29</mn></mrow></msup><mtext>Si</mtext></mrow></math></span> MAS solid NMR, and SEM-EDX, this study is devoted to investigating the impacts of curing temperature, rock type, and the addition of nano-silica (NS), on the tensile strength and failure mechanism of rock–cement sample. The experimental results show that both the curing temperature and the addition of NS leads to the formation of more C-S-H, which densifies the ITZ microstructure and responsible for high tensile strength of rock–cement samples; the tensile strengths of shale-cement samples are consistently higher than those of sandstone-cement sample; the crack velocities for rock–cement samples under three-point bending tests are approximately 1 mm/s, the crack velocities for rock–cement samples are slowed down when the NS is incorporated in cement paste, but they are independent on the rock type and curing temperature.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"186 ","pages":"Article 107673"},"PeriodicalIF":10.9,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319669","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}
Understanding the drying shrinkage of low Ca/Si ratio cement pastes is crucial for promoting the use of low-clinker ratio cementitious materials and reducing the environmental impact of cement production. We prepared well-hydrated cement paste samples with various fly ash replacement and water-to-cement ratios. The long-term drying shrinkage was measured by 1 mm-thick samples. Results showed that fly ash containing samples exhibited lower shrinkage and the irreversible part of drying shrinkage was less compared to those without fly ash. Chemical composition analysis of the calcium aluminate-silicates hydrate (C-A-S-H) was conducted using X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). Additionally, water vapor sorption isotherms and proton nuclear magnetic resonance (1H NMR) relaxometry were used to determine specific surface area and pore structure. By analyzing these results in conjunction with the C-A-S-H model, we attributed the reduced and more reversible drying shrinkage in fly ash cement to lower Ca ion amounts in the interlayer space and fewer trapped larger pores.
了解低 Ca/Si 比水泥浆的干燥收缩率对于推广使用低熟料比胶凝材料和减少水泥生产对环境的影响至关重要。我们制备了不同粉煤灰掺量和水灰比的充分水化水泥浆样品。用 1 毫米厚的样品测量了长期干燥收缩率。结果表明，与不含粉煤灰的样品相比，含粉煤灰的样品收缩率较低，且干燥收缩的不可逆部分较小。使用 X 射线衍射（XRD）和能量色散 X 射线光谱（EDS）对水合铝酸钙-硅酸盐（C-A-S-H）进行了化学成分分析。此外，还利用水蒸气吸附等温线和质子核磁共振（1H NMR）弛豫测定法确定了比表面积和孔隙结构。通过将这些结果与 C-A-S-H 模型相结合进行分析，我们将粉煤灰水泥干燥收缩的减少和可逆性归因于层间空间的钙离子含量较低以及捕获的较大孔隙较少。
{"title":"Shrinkage reduction mechanism of low Ca/Si ratio C-A-S-H in cement pastes containing fly ash","authors":"Miki Segawa , Ryo Kurihara , Abudushalamu Aili , Go Igarashi , Ippei Maruyama","doi":"10.1016/j.cemconres.2024.107683","DOIUrl":"10.1016/j.cemconres.2024.107683","url":null,"abstract":"<div><div>Understanding the drying shrinkage of low Ca/Si ratio cement pastes is crucial for promoting the use of low-clinker ratio cementitious materials and reducing the environmental impact of cement production. We prepared well-hydrated cement paste samples with various fly ash replacement and water-to-cement ratios. The long-term drying shrinkage was measured by 1 mm-thick samples. Results showed that fly ash containing samples exhibited lower shrinkage and the irreversible part of drying shrinkage was less compared to those without fly ash. Chemical composition analysis of the calcium aluminate-silicates hydrate (C-A-S-H) was conducted using X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS). Additionally, water vapor sorption isotherms and proton nuclear magnetic resonance (<sup>1</sup>H NMR) relaxometry were used to determine specific surface area and pore structure. By analyzing these results in conjunction with the C-A-S-H model, we attributed the reduced and more reversible drying shrinkage in fly ash cement to lower Ca ion amounts in the interlayer space and fewer trapped larger pores.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"186 ","pages":"Article 107683"},"PeriodicalIF":10.9,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319670","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 : 2024-09-25DOI: 10.1016/j.cemconres.2024.107640
Harald Kloft , Bartłomiej Sawicki , Freek Bos , Robin Dörrie , Niklas Freund , Stefan Gantner , Lukas Gebhard , Norman Hack , Egor Ivaniuk , Jacques Kruger , Walter Kaufmann , Jaime Mata-Falcón , Viktor Mechtcherine , Ammar Mirjan , Rob Wolfs , Dirk Lowke
Material, manufacturing process, and form are mutually dependent. In formwork-based concrete construction, the reinforcement must be positioned and fixed in the formwork, limiting material efficiency and freedom of form. In Digital Fabrication with Concrete (DFC), the formwork no longer limits the concrete forming process. Furthermore, the reinforcement no longer must be installed in advance, but can be placed before, during or after the concrete application. Therefore, the role of reinforcement and its interaction with processing must be fundamentally rethought in DFC. Furthermore, with reinforcement integration a concrete component expands from a contour-based shape into a structural form.
The current paper proposes a new so-called RPF-framework expressing the interaction of reinforcement, process and form in DFC. The application of this framework is illustrated using current examples of DFC, whose structural forms are critically discussed. Finally, the need for a holistic approach to material, process and form in DFC is emphasised.
{"title":"Interaction of reinforcement, process, and form in Digital Fabrication with Concrete","authors":"Harald Kloft , Bartłomiej Sawicki , Freek Bos , Robin Dörrie , Niklas Freund , Stefan Gantner , Lukas Gebhard , Norman Hack , Egor Ivaniuk , Jacques Kruger , Walter Kaufmann , Jaime Mata-Falcón , Viktor Mechtcherine , Ammar Mirjan , Rob Wolfs , Dirk Lowke","doi":"10.1016/j.cemconres.2024.107640","DOIUrl":"10.1016/j.cemconres.2024.107640","url":null,"abstract":"<div><div>Material, manufacturing process, and form are mutually dependent. In formwork-based concrete construction, the reinforcement must be positioned and fixed in the formwork, limiting material efficiency and freedom of form. In Digital Fabrication with Concrete (DFC), the formwork no longer limits the concrete forming process. Furthermore, the reinforcement no longer must be installed in advance, but can be placed before, during or after the concrete application. Therefore, the role of reinforcement and its interaction with processing must be fundamentally rethought in DFC. Furthermore, with reinforcement integration a concrete component expands from a contour-based shape into a structural form.</div><div>The current paper proposes a new so-called RPF-framework expressing the interaction of reinforcement, process and form in DFC. The application of this framework is illustrated using current examples of DFC, whose structural forms are critically discussed. Finally, the need for a holistic approach to material, process and form in DFC is emphasised.</div></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"186 ","pages":"Article 107640"},"PeriodicalIF":10.9,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319671","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 : 2024-09-24DOI: 10.1016/j.cemconres.2024.107684
Andreas Leemann , Beat Münch , Barbara Lothenbach , Frank Winnefeld , Paul Dunlop
Thousands of homes in County Donegal, Ireland, built from concrete blocks, are damaged by extensive cracks and crumbling that occurred a few years after construction. Recently, research has shown that pyrrhotite oxidation triggering internal sulfate attack (ISA) is the cause. In this study, samples from the strip foundations, the rising blocks, the outer and inner leaf of one undamaged reference home and three affected homes are investigated. As these four structural components differ by concrete quality, exposure condition or both, their effect on ISA is investigated. All three damaged homes contained pyrrhotite in the aggregates, while it was absent in the reference home. ISA in the foundations is in an initial state. It has progressed further in the rising blocks and is most advanced in the outer leaf. Whilst carbonation limits the effects of ISA in the inner leaf, further pyrrhotite oxidation will create expansion leading to ongoing deterioration.
在爱尔兰多尼戈尔郡，数以千计用混凝土砌块建造的房屋在建成几年后就出现了大面积的裂缝和坍塌。最近的研究表明，黄铁矿氧化引发的内部硫酸盐侵蚀（ISA）是造成这种现象的原因。在本研究中，我们对一栋未损坏的参照房屋和三栋受影响房屋的条形地基、隆起块、外叶和内叶进行了取样调查。由于这四个结构组件在混凝土质量、暴露条件或两者方面存在差异，因此研究了它们对 ISA 的影响。所有三个受损房屋的骨料中都含有黄铁矿，而参照房屋中则没有。地基中的 ISA 处于初始状态。它在升起的砖块中进一步发展，在外层叶片中最为严重。虽然碳化作用限制了内叶中 ISA 的影响，但黄铁矿的进一步氧化将产生膨胀，导致持续恶化。
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