Pub Date : 2023-11-16DOI: 10.21809/rilemtechlett.2023.177
E. Bernard, Hoang Nguyen, S. Kawashima, B. Lothenbach, Hegoi Manzano, John Provis, Allan Scott, C. Unluer, F. Winnefeld, P. Kinnunen
The cement industry is a major contributor to the anthropogenic CO2 emissions, with about 8% of all emissions coming from this sector. The global cement and concrete association has set a goal to achieve net-zero CO2 concrete by 2050, with 45% of the reduction coming from alternatives to Portland cement, substitution, and carbon capture and utilization/storage (CCU/S) approaches. Magnesia-based cements offer a conceivable solution to this problem due to their potential for low-to-negative CO2 emissions (CCU/S) but also being alternatives to Portland cement. The sources of magnesia can come from magnesium silicates or desalination brines which are carbon free for raw-material-related emissions (cf. carbonated rocks). This opens up possibilities for low or even net-negative carbon emissions. However, research on magnesia-based cements is still in its early stages. In this paper, we summarize the current understanding of different MgO-based cements and their chemistries: magnesia oxysulfate cement, magnesia oxychloride cement, magnesia carbonate cement, and magnesia silicate cement. We also discuss relevant research needed for MgO-based cements and concretes including the issues relating to the low pH of these cements and suitability of steel reinforcement. Alternatives reinforcements, suitable admixtures, and durability studies are the most needed for the further development of MgO-based concretes to achieve a radical CO2 reduction in this industry. Additionally, techno-economic and life cycle assessments are also needed to assess the competition of raw materials and the produced binder or concrete with other solutions. Overall, magnesia-based cements are a promising emerging technology that requires further research and development to realize their potential in reducing CO2 emissions in the construction industry.
{"title":"MgO-based cements – Current status and opportunities","authors":"E. Bernard, Hoang Nguyen, S. Kawashima, B. Lothenbach, Hegoi Manzano, John Provis, Allan Scott, C. Unluer, F. Winnefeld, P. Kinnunen","doi":"10.21809/rilemtechlett.2023.177","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2023.177","url":null,"abstract":"The cement industry is a major contributor to the anthropogenic CO2 emissions, with about 8% of all emissions coming from this sector. The global cement and concrete association has set a goal to achieve net-zero CO2 concrete by 2050, with 45% of the reduction coming from alternatives to Portland cement, substitution, and carbon capture and utilization/storage (CCU/S) approaches. Magnesia-based cements offer a conceivable solution to this problem due to their potential for low-to-negative CO2 emissions (CCU/S) but also being alternatives to Portland cement. The sources of magnesia can come from magnesium silicates or desalination brines which are carbon free for raw-material-related emissions (cf. carbonated rocks). This opens up possibilities for low or even net-negative carbon emissions. However, research on magnesia-based cements is still in its early stages. In this paper, we summarize the current understanding of different MgO-based cements and their chemistries: magnesia oxysulfate cement, magnesia oxychloride cement, magnesia carbonate cement, and magnesia silicate cement. We also discuss relevant research needed for MgO-based cements and concretes including the issues relating to the low pH of these cements and suitability of steel reinforcement. Alternatives reinforcements, suitable admixtures, and durability studies are the most needed for the further development of MgO-based concretes to achieve a radical CO2 reduction in this industry. Additionally, techno-economic and life cycle assessments are also needed to assess the competition of raw materials and the produced binder or concrete with other solutions. Overall, magnesia-based cements are a promising emerging technology that requires further research and development to realize their potential in reducing CO2 emissions in the construction industry.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":"11 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139268142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-14DOI: 10.21809/rilemtechlett.2023.182
Viktor Mechtcherine
Superabsorbent polymers (SAP) are highly promising chemical admixtures for concrete, offering numerous advantages in terms of water control within the mixture. These polymers present exciting possibilities for enhancing the rheological properties of fresh concrete and addressing challenges related to autogenous and plastic shrinkage through internal curing. An interesting characteristic of SAP is their ability to create stable pore systems regardless of the consistency of the concrete, the addition of superplasticizers, or the chosen method of placement and compaction. As a result, SAP emerges as a viable alternative to air-entrainment agents. While the benefits of using SAP are evident, there is a lack of standards regulating their application by concrete producers. In this regard, the recommendations offered by RILEM may pave the path toward formal regulation. This article aims to provide an overview of these recommendations.
超强吸水性聚合物（SAP）是一种非常有前途的混凝土化学外加剂，在混合物的水分控制方面具有诸多优势。这些聚合物为提高新拌混凝土的流变性能以及通过内部养护解决与自生收缩和塑性收缩相关的难题提供了令人兴奋的可能性。SAP 的一个有趣特点是，无论混凝土的稠度、超塑化剂的添加量或所选择的浇筑和压实方法如何，它们都能形成稳定的孔隙系统。因此，SAP 成为引气剂的可行替代品。虽然使用 SAP 的好处显而易见，但缺乏规范混凝土生产商应用 SAP 的标准。在这方面，RILEM 提出的建议可能会为制定正式法规铺平道路。本文旨在概述这些建议。
{"title":"Guidelines for using superabsorbent polymers (SAP) in concrete construction","authors":"Viktor Mechtcherine","doi":"10.21809/rilemtechlett.2023.182","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2023.182","url":null,"abstract":"Superabsorbent polymers (SAP) are highly promising chemical admixtures for concrete, offering numerous advantages in terms of water control within the mixture. These polymers present exciting possibilities for enhancing the rheological properties of fresh concrete and addressing challenges related to autogenous and plastic shrinkage through internal curing. An interesting characteristic of SAP is their ability to create stable pore systems regardless of the consistency of the concrete, the addition of superplasticizers, or the chosen method of placement and compaction. As a result, SAP emerges as a viable alternative to air-entrainment agents. While the benefits of using SAP are evident, there is a lack of standards regulating their application by concrete producers. In this regard, the recommendations offered by RILEM may pave the path toward formal regulation. This article aims to provide an overview of these recommendations.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139277389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-08DOI: 10.21809/rilemtechlett.2023.179
Franco Zunino
Concrete is by a substantial margin the most widely used construction material. Projections indicate that the demand for concrete it will continue to increase to sustain the development of emerging economies. This paper presents a new perspective of low-carbon concrete by refocusing on the actual final product, highlighting the tremendous CO2 saving opportunities of reducing the total paste volume of concrete while simultaneously using high performance, low-clinker cements in the so-called two-fold strategy (low clinker content, low paste volume concrete formulations). Different aspects of low paste volume concrete formulations are discussed based on a combination of published and new concrete performance data, showing the potential for CO2 savings of the strategy and the technical opportunities to retain the robustness and reliability that make concrete such a versatile and widely used material. Chemical admixtures play a crucial role in reaching those objectives, as they enable to reduce the cement content while retaining the needed workability (slump and slump retention) for each application. The key issues relating to using those admixtures in low carbon concrete are highlighted.
{"title":"A two-fold strategy towards low-carbon concrete","authors":"Franco Zunino","doi":"10.21809/rilemtechlett.2023.179","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2023.179","url":null,"abstract":"Concrete is by a substantial margin the most widely used construction material. Projections indicate that the demand for concrete it will continue to increase to sustain the development of emerging economies. This paper presents a new perspective of low-carbon concrete by refocusing on the actual final product, highlighting the tremendous CO2 saving opportunities of reducing the total paste volume of concrete while simultaneously using high performance, low-clinker cements in the so-called two-fold strategy (low clinker content, low paste volume concrete formulations). Different aspects of low paste volume concrete formulations are discussed based on a combination of published and new concrete performance data, showing the potential for CO2 savings of the strategy and the technical opportunities to retain the robustness and reliability that make concrete such a versatile and widely used material. Chemical admixtures play a crucial role in reaching those objectives, as they enable to reduce the cement content while retaining the needed workability (slump and slump retention) for each application. The key issues relating to using those admixtures in low carbon concrete are highlighted.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":"133 6‐8","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135392510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-08DOI: 10.21809/rilemtechlett.2023.180
Guoqing Geng, Zhe Zhang
Calcium silicate hydrate (C-S-H) is the primary binding phase in modern concrete. While significant progress has been made in understanding the structure and behavior of C-S-H at atomistic scale and macro scale, there lacks a theory that links them. This review paper focuses on identifying the key challenges in bridging the gap between the atomic-scale characteristics of C-S-H and its larger scale mechanical behaviors. Recent experimental and simulation work on the multiscale mechanical properties of C-S-H is summarized. The need for integrating experimental observations, theoretical models, and computational simulations to establish a comprehensive and predictive bottom-up theory of the mechanical properties of C-S-H is highlighted. Such a theory will enable a deeper understanding of C-S-H behavior and pave the way for the design and optimization of cementitious materials with tailored mechanical performance.
{"title":"The missing link in the bottom-up theory of mechanical properties of calcium silicate hydrate","authors":"Guoqing Geng, Zhe Zhang","doi":"10.21809/rilemtechlett.2023.180","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2023.180","url":null,"abstract":"Calcium silicate hydrate (C-S-H) is the primary binding phase in modern concrete. While significant progress has been made in understanding the structure and behavior of C-S-H at atomistic scale and macro scale, there lacks a theory that links them. This review paper focuses on identifying the key challenges in bridging the gap between the atomic-scale characteristics of C-S-H and its larger scale mechanical behaviors. Recent experimental and simulation work on the multiscale mechanical properties of C-S-H is summarized. The need for integrating experimental observations, theoretical models, and computational simulations to establish a comprehensive and predictive bottom-up theory of the mechanical properties of C-S-H is highlighted. Such a theory will enable a deeper understanding of C-S-H behavior and pave the way for the design and optimization of cementitious materials with tailored mechanical performance.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":"36 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135430394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-21DOI: 10.21809/rilemtechlett.2023.176
A. Yahia, A. Perrot, D. Feys, K. Khayat, M. Sonebi, S. Kawashima, Wolfram Schimdt
Fresh cement pastes behave as viscoelastic materials below the flow onset. The measurements of viscoelastic properties of fresh cement paste provide valuable insight into the dispersion of solid particles as well as the hydration kinetics at early age and its influence on the structural evolution and solidification behavior at quasi-static conditions. Monitoring the development of viscoelastic properties of fresh cement paste using dynamic oscillatory shear measurements can also elucidate the working mechanisms of chemical admixtures. These properties are efficient indicators to guide mixture proportion design and are necessary to understand the rheology and stability of concrete. In this paper, the most common techniques, including dynamic oscillatory measurements, used to assess the viscoelastic properties of fresh cement paste are presented and discussed. The measurement challenges and their effects on the accuracy of the obtained properties are highlighted. On the other hand, the effects of high-range water-reducer, viscosity-modifying admixture, and supplementary cementitious materials are discussed. Furthermore, the use of viscoelastic measurements to assess yield stress and structural build-up of cement paste is presented.
{"title":"Viscoelastic properties of fresh cement paste: measuring procedures and influencing parameters","authors":"A. Yahia, A. Perrot, D. Feys, K. Khayat, M. Sonebi, S. Kawashima, Wolfram Schimdt","doi":"10.21809/rilemtechlett.2023.176","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2023.176","url":null,"abstract":"Fresh cement pastes behave as viscoelastic materials below the flow onset. The measurements of viscoelastic properties of fresh cement paste provide valuable insight into the dispersion of solid particles as well as the hydration kinetics at early age and its influence on the structural evolution and solidification behavior at quasi-static conditions. Monitoring the development of viscoelastic properties of fresh cement paste using dynamic oscillatory shear measurements can also elucidate the working mechanisms of chemical admixtures. These properties are efficient indicators to guide mixture proportion design and are necessary to understand the rheology and stability of concrete. In this paper, the most common techniques, including dynamic oscillatory measurements, used to assess the viscoelastic properties of fresh cement paste are presented and discussed. The measurement challenges and their effects on the accuracy of the obtained properties are highlighted. On the other hand, the effects of high-range water-reducer, viscosity-modifying admixture, and supplementary cementitious materials are discussed. Furthermore, the use of viscoelastic measurements to assess yield stress and structural build-up of cement paste is presented.\u0000 ","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68366200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-18DOI: 10.21809/rilemtechlett.2023.172
A. S. Basavaraj, Hareesh Muni, Yuvaraj Dhandapani, R. Gettu, M. Santhanam
In this work, limestone-calcined clay (LC2) is studied as an alternative supplementary cementitious material (SCM), combining two widely available resources – calcinated kaolinitic clay and limestone, to partially substitute portland clinker. The primary goal is to assess the potential of LC2 to produce moderate to high strength concretes with design compressive strengths of 20 to 50 MPa. For this purpose, 27 mixes with LC2 were prepared with a range of binder contents and water-binder ratios, and the performance was benchmarked against those of mixes having fly ash (PFA). In addition to the quantification of strength and concrete resistivity, life cycle assessment was performed for the concretes considering a typical situation in India. The efficiency of concretes made with LC2, PFA and ordinary portland cement (OPC) was analyzed using the energy intensity index (eics) and apathy index (A-index) as sustainability indicators. This framework establishes the sustainability potential of the LC2 with insights on the influence of strength on the indicators. It is concluded that the LC2 concretes with 45% replacement level, w/b≤0.45 and binder content lower than 400 kg/m3 possess the highest sustainability potential, among the concretes studied here.
{"title":"Limestone-Calcined Clay (LC2) as a supplementary cementitious material for concrete","authors":"A. S. Basavaraj, Hareesh Muni, Yuvaraj Dhandapani, R. Gettu, M. Santhanam","doi":"10.21809/rilemtechlett.2023.172","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2023.172","url":null,"abstract":"In this work, limestone-calcined clay (LC2) is studied as an alternative supplementary cementitious material (SCM), combining two widely available resources – calcinated kaolinitic clay and limestone, to partially substitute portland clinker. The primary goal is to assess the potential of LC2 to produce moderate to high strength concretes with design compressive strengths of 20 to 50 MPa. For this purpose, 27 mixes with LC2 were prepared with a range of binder contents and water-binder ratios, and the performance was benchmarked against those of mixes having fly ash (PFA). In addition to the quantification of strength and concrete resistivity, life cycle assessment was performed for the concretes considering a typical situation in India. The efficiency of concretes made with LC2, PFA and ordinary portland cement (OPC) was analyzed using the energy intensity index (eics) and apathy index (A-index) as sustainability indicators. This framework establishes the sustainability potential of the LC2 with insights on the influence of strength on the indicators. It is concluded that the LC2 concretes with 45% replacement level, w/b≤0.45 and binder content lower than 400 kg/m3 possess the highest sustainability potential, among the concretes studied here.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44964448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-04DOI: 10.21809/rilemtechlett.2023.173
Joseph Mwiti Marangu, A. Marsh, D. Panesar, N. Radebe, Alicia Regodon Puyalto, W. Schmidt, L. Valentini
Though the technical knowledge to make cement and concrete more sustainable already exists, implementation of solutions lags behind the rate needed to mitigate climate change and meet the targets set by the Sustainable Development Goals. Whilst most of the focus around the built environment is on embodied carbon, we stress an important but neglected dimension: partnership (SDG17). Effective partnerships can be powerful enablers to accelerate sustainable solutions in cement and concrete, and let such solutions transfer from academia to the market. This can be achieved through knowledge generation, solution implementation, and policy development, among other routes. In this article, we share five recommendations for how partnerships can address neglected research questions and practical needs: 1) reform Science, Technology, Engineering and Mathematics (STEM) education to train “circular citizens”; 2) map out routes by which cementitious materials can contribute to a “localization” agenda; 3) generate open-access maps for the geographical distribution of primary and secondary raw materials; 4) predict the long-term environmental performance of different solutions for low-CO2 cements in different geographical areas; 5) overhaul standards to be technically and regionally fit for purpose. These approaches have the potential to make a unique and substantial contribution towards achieving collective sustainability goals.
{"title":"Five recommendations to accelerate sustainable solutions in cement and concrete through partnership","authors":"Joseph Mwiti Marangu, A. Marsh, D. Panesar, N. Radebe, Alicia Regodon Puyalto, W. Schmidt, L. Valentini","doi":"10.21809/rilemtechlett.2023.173","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2023.173","url":null,"abstract":"Though the technical knowledge to make cement and concrete more sustainable already exists, implementation of solutions lags behind the rate needed to mitigate climate change and meet the targets set by the Sustainable Development Goals. Whilst most of the focus around the built environment is on embodied carbon, we stress an important but neglected dimension: partnership (SDG17). Effective partnerships can be powerful enablers to accelerate sustainable solutions in cement and concrete, and let such solutions transfer from academia to the market. This can be achieved through knowledge generation, solution implementation, and policy development, among other routes. In this article, we share five recommendations for how partnerships can address neglected research questions and practical needs: 1) reform Science, Technology, Engineering and Mathematics (STEM) education to train “circular citizens”; 2) map out routes by which cementitious materials can contribute to a “localization” agenda; 3) generate open-access maps for the geographical distribution of primary and secondary raw materials; 4) predict the long-term environmental performance of different solutions for low-CO2 cements in different geographical areas; 5) overhaul standards to be technically and regionally fit for purpose. These approaches have the potential to make a unique and substantial contribution towards achieving collective sustainability goals.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47018078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-04-26DOI: 10.21809/rilemtechlett.2022.165
K. Scrivener, Mohsen Ben Haha, P. Juilland, Christophe Levy
The needs for research on cementitious materials are reviewed with a focus on Europe. These are considered under 8 topics: clinker production, alternatives to Portland cement, composite cements based on Portland clinker, concrete, admixtures, durability, recycling, digitisation in concrete construction, and, carbon capture and use or storage; finally, the key research questions and their potential for CO2 reduction are summarised in a “Watermelon” diagram with a list of 30 key questions to be addressed (see Appendix).
{"title":"Research needs for cementitious building materials with focus on Europe","authors":"K. Scrivener, Mohsen Ben Haha, P. Juilland, Christophe Levy","doi":"10.21809/rilemtechlett.2022.165","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2022.165","url":null,"abstract":"The needs for research on cementitious materials are reviewed with a focus on Europe. These are considered under 8 topics: clinker production, alternatives to Portland cement, composite cements based on Portland clinker, concrete, admixtures, durability, recycling, digitisation in concrete construction, and, carbon capture and use or storage; finally, the key research questions and their potential for CO2 reduction are summarised in a “Watermelon” diagram with a list of 30 key questions to be addressed (see Appendix).","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42675415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-03-23DOI: 10.21809/rilemtechlett.2022.175
A. Kunhi Mohamed, A. Bouibes, M. Bauchy, Ziga Casar
Developing new sustainable concrete technology has become an urgent need, requiring faster and deeper insights into the fundamental mechanisms driving the cement hydration reactions. Molecular simulations have the potential to provide such understanding since the hydration reaction and the cement chemistry are particularly dominated by mechanisms at the atomic scale. In this letter, we review the application of two major approaches namely classical (including reactive) molecular dynamics simulations and density function theory calculations of cementitious materials. We give an overview of molecular simulations involving the major mineral and hydrate phases.
{"title":"Molecular modelling of cementitious materials: current progress and benefits","authors":"A. Kunhi Mohamed, A. Bouibes, M. Bauchy, Ziga Casar","doi":"10.21809/rilemtechlett.2022.175","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2022.175","url":null,"abstract":"Developing new sustainable concrete technology has become an urgent need, requiring faster and deeper insights into the fundamental mechanisms driving the cement hydration reactions. Molecular simulations have the potential to provide such understanding since the hydration reaction and the cement chemistry are particularly dominated by mechanisms at the atomic scale. In this letter, we review the application of two major approaches namely classical (including reactive) molecular dynamics simulations and density function theory calculations of cementitious materials. We give an overview of molecular simulations involving the major mineral and hydrate phases.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43058292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-02-20DOI: 10.21809/rilemtechlett.2022.168
E. Lloret-Fritschi, Joseph Choma, F. Scotto, A. Szabo, F. Gramazio, M. Kohler, R. Flatt
Concrete is one of the most used materials after water. Largely owing to this, its environmental impact is substantial, although its embodied carbon per unit volume or mass is low when compared to most alternatives. This, along with the broad availability, good strength, durability and versatility of concrete means that it will remain a material of choice, although more efficient ways of using it must be found. Structurally optimized building components are a means to do this as they can save about 50% material. Unfortunately, however, such elements are presently too expensive to produce owing to them requiring non-standard formwork. It is an objective of digital fabrication to propose solutions to this issue. In this con-text, Digital Casting Systems (DCS) have advanced material control strategies for setting-on-demand in digital concrete processing. Thereby, the formwork pressure is reduced to a minimum, which opens possibilities of rethinking formworks as systems that are dynamically shaping, millimetre thin or weakly supporting the material cast inside. In this paper we present a brief overview of millimetre thin formworks and summarize the first realization of concrete elements that utilizes the mechanics of paper folding to make millimetre thin formworks up to 2.5 meters high. Such formworks could initially be flat packed, erected into shape, and eventually peeled-off and recycled in established material streams. This would reduce waste and transport cost, while offering a surface finish that meets the expectations for exposed concrete surfaces.
{"title":"In-Crease: Less Concrete More Paper","authors":"E. Lloret-Fritschi, Joseph Choma, F. Scotto, A. Szabo, F. Gramazio, M. Kohler, R. Flatt","doi":"10.21809/rilemtechlett.2022.168","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2022.168","url":null,"abstract":"Concrete is one of the most used materials after water. Largely owing to this, its environmental impact is substantial, although its embodied carbon per unit volume or mass is low when compared to most alternatives. This, along with the broad availability, good strength, durability and versatility of concrete means that it will remain a material of choice, although more efficient ways of using it must be found.\u0000Structurally optimized building components are a means to do this as they can save about 50% material. Unfortunately, however, such elements are presently too expensive to produce owing to them requiring non-standard formwork. It is an objective of digital fabrication to propose solutions to this issue. In this con-text, Digital Casting Systems (DCS) have advanced material control strategies for setting-on-demand in digital concrete processing. Thereby, the formwork pressure is reduced to a minimum, which opens possibilities of rethinking formworks as systems that are dynamically shaping, millimetre thin or weakly supporting the material cast inside.\u0000In this paper we present a brief overview of millimetre thin formworks and summarize the first realization of concrete elements that utilizes the mechanics of paper folding to make millimetre thin formworks up to 2.5 meters high. Such formworks could initially be flat packed, erected into shape, and eventually peeled-off and recycled in established material streams. This would reduce waste and transport cost, while offering a surface finish that meets the expectations for exposed concrete surfaces.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41632742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：