Pub Date : 2021-12-29DOI: 10.21809/rilemtechlett.2021.150
P. Suraneni
Identification and rapid characterization of novel supplementary cementitious materials (SCMs) is a critical need, driven by shortfalls in conventional SCMs. In this study, we present a discussion of recently developed reactivity tests – the R3 test, the modified R3 test, the lime strength test, and the bulk resistivity index test. These tests measure reactivity parameters such as heat release, bound water, calcium hydroxide consumption, strength, and bulk resistivity. All tests can screen inert from reactive materials. To additionally differentiate pozzolanic and latent hydraulic materials, two parameters, for example, calcium hydroxide consumption and heat release, are needed. The influences of SCM bulk chemistry, amorphous content, and fineness on measured reactivity are outlined. Reactivity test outputs can predict strength and durability of cement paste/mortar/concrete; however, caution must be exercised as these properties are influenced by a variety of other factors independent of reactivity. Thoughts are provided on using reactivity tests to screen materials for concrete durability.
{"title":"Recent developments in reactivity testing of supplementary cementitious materials","authors":"P. Suraneni","doi":"10.21809/rilemtechlett.2021.150","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2021.150","url":null,"abstract":"Identification and rapid characterization of novel supplementary cementitious materials (SCMs) is a critical need, driven by shortfalls in conventional SCMs. In this study, we present a discussion of recently developed reactivity tests – the R3 test, the modified R3 test, the lime strength test, and the bulk resistivity index test. These tests measure reactivity parameters such as heat release, bound water, calcium hydroxide consumption, strength, and bulk resistivity. All tests can screen inert from reactive materials. To additionally differentiate pozzolanic and latent hydraulic materials, two parameters, for example, calcium hydroxide consumption and heat release, are needed. The influences of SCM bulk chemistry, amorphous content, and fineness on measured reactivity are outlined. Reactivity test outputs can predict strength and durability of cement paste/mortar/concrete; however, caution must be exercised as these properties are influenced by a variety of other factors independent of reactivity. Thoughts are provided on using reactivity tests to screen materials for concrete durability.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47531473","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 : 2021-12-07DOI: 10.21809/rilemtechlett.2021.120
F. Lolli, K. Kurtis
The capital investment in the US for construction and maintenance of the infrastructure road network is $150 billion/year. Investments in OECD countries will likely stabilize, while other countries will face an exponential growth of investments for infrastructures driven by the development of metropolitan cities. Continued “business-as-usual” practice for portland and asphalt cement concrete pavement construction ignores the increasing warning calls for the identification of more sustainable and less energy intensive paving materials. Alkali activated materials concrete (AAM) have been studied with growing interest during the last three decades. AAM show promising results in terms of mechanical performance, while also having a global warming potential impact 30-80% less than that of portland cement concrete. The global warming potential of AAM is closely dependent on the: 1) activating solution used to activate the raw material and 2) origin of the raw material. Specifically, the impact of the transport for both of these components is ~ 10% of its global warming potential. Hence, to increase the adoption of AAM for pavements, it is fundamental to analyze the existing literature to clarify the link between environmental impact and mechanical performance, identifying opportunities for applications that are tailored to the local availability of raw material.
{"title":"Life Cycle Assessment of alkali activated materials: preliminary investigation for pavement applications","authors":"F. Lolli, K. Kurtis","doi":"10.21809/rilemtechlett.2021.120","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2021.120","url":null,"abstract":"The capital investment in the US for construction and maintenance of the infrastructure road network is $150 billion/year. Investments in OECD countries will likely stabilize, while other countries will face an exponential growth of investments for infrastructures driven by the development of metropolitan cities. Continued “business-as-usual” practice for portland and asphalt cement concrete pavement construction ignores the increasing warning calls for the identification of more sustainable and less energy intensive paving materials. \u0000Alkali activated materials concrete (AAM) have been studied with growing interest during the last three decades. AAM show promising results in terms of mechanical performance, while also having a global warming potential impact 30-80% less than that of portland cement concrete. The global warming potential of AAM is closely dependent on the: 1) activating solution used to activate the raw material and 2) origin of the raw material. Specifically, the impact of the transport for both of these components is ~ 10% of its global warming potential. Hence, to increase the adoption of AAM for pavements, it is fundamental to analyze the existing literature to clarify the link between environmental impact and mechanical performance, identifying opportunities for applications that are tailored to the local availability of raw material.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44487004","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 : 2021-07-26DOI: 10.21809/rilemtechlett.2021.138
J. Duchesne, A. Rodrigues, B. Fournier
Oxidation of pyrrhotite-bearing aggregates is one of the major causes of concrete damage in numerous buildings in Trois-Rivières in Canada and Connecticut in the USA. In the presence of moisture and oxygen, pyrrhotite oxidizes to generate iron-and sulfate-rich secondary minerals that cause internal sulfate attack. Iron sulfides are accessory minerals of different rock types. The distribution of sulfides is often very heterogeneous in terms of aggregate particles, even at the level of the quarries in which some areas may contain copious amounts than others, which complicates the sampling method. Pyrrhotite is a complex mineral with varying chemical composition, crystallographic structure, and specific surface area. These factors influence the reactivity of pyrrhotite. Therefore, it is challenging to control the quality of the aggregate sources. In this study, recent advances in the identification and quantification of pyrrhotite to diagnose complicated cases are presented, and a performance-based approach for the quality control of new sources of aggregates is introduced. The performance-based approach is preferred because it eliminates the influence of the oxidation of pyrrhotite.
{"title":"Concrete damage due to oxidation of pyrrhotite-bearing aggregate: a review","authors":"J. Duchesne, A. Rodrigues, B. Fournier","doi":"10.21809/rilemtechlett.2021.138","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2021.138","url":null,"abstract":"Oxidation of pyrrhotite-bearing aggregates is one of the major causes of concrete damage in numerous buildings in Trois-Rivières in Canada and Connecticut in the USA. In the presence of moisture and oxygen, pyrrhotite oxidizes to generate iron-and sulfate-rich secondary minerals that cause internal sulfate attack. Iron sulfides are accessory minerals of different rock types. The distribution of sulfides is often very heterogeneous in terms of aggregate particles, even at the level of the quarries in which some areas may contain copious amounts than others, which complicates the sampling method. Pyrrhotite is a complex mineral with varying chemical composition, crystallographic structure, and specific surface area. These factors influence the reactivity of pyrrhotite. Therefore, it is challenging to control the quality of the aggregate sources. \u0000In this study, recent advances in the identification and quantification of pyrrhotite to diagnose complicated cases are presented, and a performance-based approach for the quality control of new sources of aggregates is introduced. The performance-based approach is preferred because it eliminates the influence of the oxidation of pyrrhotite.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48779394","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 : 2021-07-22DOI: 10.21809/RILEMTECHLETT.2021.136
C. Hall, Gloria J. Lo, A. Hamilton
Moisture buffering describes the use of materials with high water-vapour sorption capacity to provide humidity control in interior spaces. Established models of the moisture dynamics of buffering are derived from conventional Fickian vapour-diffusion equations. We describe an alternative analysis using a Sharp-Front formulation. This yields a similar expression for the moisture effusivity, several consistent scalings and a new definition of the moisture penetration depth. Features of the model are compared with some published experimental data. A new sorption buffer index is a measurable experimental property that describes the water-vapour buffer strength of the material.
{"title":"Sharp Front analysis of moisture buffering","authors":"C. Hall, Gloria J. Lo, A. Hamilton","doi":"10.21809/RILEMTECHLETT.2021.136","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2021.136","url":null,"abstract":"Moisture buffering describes the use of materials with high water-vapour sorption capacity to provide humidity control \u0000in interior spaces. Established models of the moisture dynamics of buffering are derived from conventional Fickian vapour-diffusion \u0000equations. We describe an alternative analysis using a Sharp-Front formulation. This yields a similar expression for the \u0000moisture effusivity, several consistent scalings and a new definition of the moisture penetration depth. Features of the model are compared with \u0000some published experimental data. A new sorption buffer index is a measurable experimental property that describes the water-vapour \u0000buffer strength of the material.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47973107","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 : 2021-07-16DOI: 10.21809/RILEMTECHLETT.2021.143
S. Ramanathan, P. Perumal, M. Illikainen, P. Suraneni
Two mine tailings are evaluated for their potential as supplementary cementitious materials. The mine tailings were milled using two different methods – ball milling for 30 minutes and disc milling for durations ranging from 1 to 15 minutes. The modified R3 test was carried out on the mine tailings to quantify their reactivity. The reactivity of the disc milled tailings is greater than those of the ball milled tailings. Strong correlations are obtained between milling duration, median particle size, amorphous content, dissolved aluminum and silicon, and reactivity of the mine tailings. The milling energy results in an increase in the fineness and the amorphous content, which do not appreciably increase beyond a disc milling duration of 8 minutes. The reactivity increases significantly beyond a certain threshold fineness and amorphous content. Cementitious pastes were prepared at 30% supplementary cementitious materials replacement level at a water-to-cementitious materials ratio of 0.40. No negative effects of the mine tailings were observed at early ages in cement pastes based on isothermal calorimetry and thermogravimetric analysis, demonstrating the potential for these materials to be used as supplementary cementitious materials.
{"title":"Mechanically activated mine tailings for use as supplementary cementitious materials","authors":"S. Ramanathan, P. Perumal, M. Illikainen, P. Suraneni","doi":"10.21809/RILEMTECHLETT.2021.143","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2021.143","url":null,"abstract":"Two mine tailings are evaluated for their potential as supplementary cementitious materials. The mine tailings were milled using two different methods – ball milling for 30 minutes and disc milling for durations ranging from 1 to 15 minutes. The modified R3 test was carried out on the mine tailings to quantify their reactivity. The reactivity of the disc milled tailings is greater than those of the ball milled tailings. Strong correlations are obtained between milling duration, median particle size, amorphous content, dissolved aluminum and silicon, and reactivity of the mine tailings. The milling energy results in an increase in the fineness and the amorphous content, which do not appreciably increase beyond a disc milling duration of 8 minutes. The reactivity increases significantly beyond a certain threshold fineness and amorphous content. Cementitious pastes were prepared at 30% supplementary cementitious materials replacement level at a water-to-cementitious materials ratio of 0.40. No negative effects of the mine tailings were observed at early ages in cement pastes based on isothermal calorimetry and thermogravimetric analysis, demonstrating the potential for these materials to be used as supplementary cementitious materials.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47529990","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 : 2021-07-15DOI: 10.21809/RILEMTECHLETT.2021.141
M. Zając, J. Skocek, J. Skibsted, Mohsen Ben Haha
This contribution discusses the carbon capture and utilization (CCU) approach based on CO2 mineralization of cement paste from recycled concrete as new approach to capture CO2 and significantly contribute to the reduction in CO2 emissions associated with cement production. The current literature suggests that all CO2 released from the decomposition of limestone during clinker production can be sequestered by carbonation of the end-of-life cement paste. This carbonation can be achieved in a few hours at ambient temperature and pressure and with a relatively low CO2 concentration (< 10 %) in the gas. The carbonation of cement paste produces calcite and an amorphous alumina-silica gel, the latter being a pozzolanic material that can be utilized as a supplementary cementitious material. The pozzolanic reaction of the alumina-silica gel is very rapid as a result of its high specific surface and amorphous structure. Thus, composite cements containing carbonated cement paste are characterized by a rapid strength gain. The successful implementation of this CCU approach relies also on improved concrete recycling techniques and methods currently under development to separate out the cement paste fines and such. Full concrete recycling will further improve the circular utilization of cement and concrete by using recycled aggregates instead of natural deposits of aggregates. Although the feasibility of the process has already been demonstrated at the industrial scale, there are still several open questions related to optimum carbonation conditions and the performance of carbonated material in novel composite cements.
{"title":"CO2 mineralization of demolished concrete wastes into a supplementary cementitious material – a new CCU approach for the cement industry","authors":"M. Zając, J. Skocek, J. Skibsted, Mohsen Ben Haha","doi":"10.21809/RILEMTECHLETT.2021.141","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2021.141","url":null,"abstract":"This contribution discusses the carbon capture and utilization (CCU) approach based on CO2 mineralization of cement paste from recycled concrete as new approach to capture CO2 and significantly contribute to the reduction in CO2 emissions associated with cement production. The current literature suggests that all CO2 released from the decomposition of limestone during clinker production can be sequestered by carbonation of the end-of-life cement paste. This carbonation can be achieved in a few hours at ambient temperature and pressure and with a relatively low CO2 concentration (< 10 %) in the gas. The carbonation of cement paste produces calcite and an amorphous alumina-silica gel, the latter being a pozzolanic material that can be utilized as a supplementary cementitious material. The pozzolanic reaction of the alumina-silica gel is very rapid as a result of its high specific surface and amorphous structure. Thus, composite cements containing carbonated cement paste are characterized by a rapid strength gain. The successful implementation of this CCU approach relies also on improved concrete recycling techniques and methods currently under development to separate out the cement paste fines and such. Full concrete recycling will further improve the circular utilization of cement and concrete by using recycled aggregates instead of natural deposits of aggregates. Although the feasibility of the process has already been demonstrated at the industrial scale, there are still several open questions related to optimum carbonation conditions and the performance of carbonated material in novel composite cements.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48640034","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 : 2021-06-08DOI: 10.21809/RILEMTECHLETT.2021.140
D. Kulik, F. Winnefeld, A. Kulik, G. Miron, B. Lothenbach
Thermodynamic equilibrium calculations for cementitious materials enable predictions of stable phases and solution composition. In the last two decades, thermodynamic modelling has been increasingly used to understand the impact of factors such as cement composition, hydration, leaching, or temperature on the phases and properties of a hydrated cementitious system. General thermodynamic modelling codes such as GEM-Selektor have versatile but complex user interfaces requiring a considerable learning and training time. Hence there is a need for a dedicated tool, easy to learn and to use, with little to no maintenance efforts. CemGEMS (https://cemgems.app) is a free-to-use web app developed to meet this need, i.e. to assist cement chemists, students and industrial engineers in easily performing and visualizing thermodynamic simulations of hydration of cementitious materials at temperatures 0-99 °C and pressures 1-100 bar. At the server side, CemGEMS runs the GEMS code (https://gems.web.psi.ch) using the PSI/Nagra and Cemdata18 chemical thermodynamic data-bases (https://www.empa.ch/cemdata). The present paper summarizes the concepts of CemGEMS and its template data, highlights unique features of value for cement chemists that are not available in other tools, presents several calculated examples related to hydration and durability of cementitious materials, and compares the results with thermodynamic modelling using the desktop GEM-Selektor code.
{"title":"CemGEMS – an easy-to-use web application for thermodynamic modeling of cementitious materials","authors":"D. Kulik, F. Winnefeld, A. Kulik, G. Miron, B. Lothenbach","doi":"10.21809/RILEMTECHLETT.2021.140","DOIUrl":"https://doi.org/10.21809/RILEMTECHLETT.2021.140","url":null,"abstract":"Thermodynamic equilibrium calculations for cementitious materials enable predictions of stable phases and solution composition. In the last two decades, thermodynamic modelling has been increasingly used to understand the impact of factors such as cement composition, hydration, leaching, or temperature on the phases and properties of a hydrated cementitious system. General thermodynamic modelling codes such as GEM-Selektor have versatile but complex user interfaces requiring a considerable learning and training time. Hence there is a need for a dedicated tool, easy to learn and to use, with little to no maintenance efforts. CemGEMS (https://cemgems.app) is a free-to-use web app developed to meet this need, i.e. to assist cement chemists, students and industrial engineers in easily performing and visualizing thermodynamic simulations of hydration of cementitious materials at temperatures 0-99 °C and pressures 1-100 bar. At the server side, CemGEMS runs the GEMS code (https://gems.web.psi.ch) using the PSI/Nagra and Cemdata18 chemical thermodynamic data-bases (https://www.empa.ch/cemdata). \u0000The present paper summarizes the concepts of CemGEMS and its template data, highlights unique features of value for cement chemists that are not available in other tools, presents several calculated examples related to hydration and durability of cementitious materials, and compares the results with thermodynamic modelling using the desktop GEM-Selektor code.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49457936","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 : 2021-01-01DOI: 10.21809/rilemtechlett.2021.146
Sabbie A. Miller, Elisabeth Van Roijen, P. Cunningham, Alyson Kim
Population growth and urbanization over the coming decades are anticipated to drive unprecedented demand for infrastructure materials and energy resources. Unfortunately, factors such as the degree of resource consumption, the energy-intensive nature of production, and the chemical-reaction driven emissions make infrastructure materials production industries among the greatest contributors to anthropogenic CO2 emissions. Yet there is an often-overlooked potential environmental benefit to infrastructure materials: most remain in use for decades and their long service lives can facilitate extended storage of carbon. In this perspective, we present an overview of recent technological advancements that can support infrastructure materials acting as a global, distributed carbon sink and discuss areas for further research and development. We present mechanisms to quantify the extent to which the embodied carbon will be removed from the carbon cycle for a long enough period of time to provide carbon sequestration and climate benefit. We conclude that it is possible to unlock the vast potential to engineer a carbon sequestration system that simultaneously meets societal need for expanding infrastructure systems; however, complexities in how these systems are engineered must be systematically and quantitatively incorporated into materials design.
{"title":"Opportunities and challenges for engineering construction materials as carbon sinks","authors":"Sabbie A. Miller, Elisabeth Van Roijen, P. Cunningham, Alyson Kim","doi":"10.21809/rilemtechlett.2021.146","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2021.146","url":null,"abstract":"Population growth and urbanization over the coming decades are anticipated to drive unprecedented demand for infrastructure materials and energy resources. Unfortunately, factors such as the degree of resource consumption, the energy-intensive nature of production, and the chemical-reaction driven emissions make infrastructure materials production industries among the greatest contributors to anthropogenic CO2 emissions. Yet there is an often-overlooked potential environmental benefit to infrastructure materials: most remain in use for decades and their long service lives can facilitate extended storage of carbon. In this perspective, we present an overview of recent technological advancements that can support infrastructure materials acting as a global, distributed carbon sink and discuss areas for further research and development. We present mechanisms to quantify the extent to which the embodied carbon will be removed from the carbon cycle for a long enough period of time to provide carbon sequestration and climate benefit. We conclude that it is possible to unlock the vast potential to engineer a carbon sequestration system that simultaneously meets societal need for expanding infrastructure systems; however, complexities in how these systems are engineered must be systematically and quantitatively incorporated into materials design.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68366444","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 : 2021-01-01DOI: 10.21809/rilemtechlett.2021.142
J. Spangenberg, Wilson Ricardo Leal da Silva, R. Comminal, M. Mollah, Thomas Juul Andersen, H. Stang
This paper presents a computational fluid dynamics model fit for multi-layer 3D Concrete Printing. The numerical model utilizes an elasto-visco-plastic constitutive model to mimic the flow behaviour of the cementitious material. To validate the model, simulation data is compared to experimental data from 3D printed walls. The obtained results show that the numerical model can reproduce the experimental results with high accuracy and quantify the extrusion load imposed upon the layers. Such load is found to exceed the material’s yields stress in certain regions of previously printed layers, leading to layer deformation/flow. The developed and validated numerical model can assist in identifying optimal printing strategies, reducing the number of costly experimental print failures and human-process interaction. By doing so, the findings of this paper helps 3D Concrete Printing move a step closer to a truly digital fabrication process.
{"title":"Numerical simulation of multi-layer 3D concrete printing","authors":"J. Spangenberg, Wilson Ricardo Leal da Silva, R. Comminal, M. Mollah, Thomas Juul Andersen, H. Stang","doi":"10.21809/rilemtechlett.2021.142","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2021.142","url":null,"abstract":"This paper presents a computational fluid dynamics model fit for multi-layer 3D Concrete Printing. The numerical model utilizes an elasto-visco-plastic constitutive model to mimic the flow behaviour of the cementitious material. To validate the model, simulation data is compared to experimental data from 3D printed walls. The obtained results show that the numerical model can reproduce the experimental results with high accuracy and quantify the extrusion load imposed upon the layers. Such load is found to exceed the material’s yields stress in certain regions of previously printed layers, leading to layer deformation/flow. The developed and validated numerical model can assist in identifying optimal printing strategies, reducing the number of costly experimental print failures and human-process interaction. By doing so, the findings of this paper helps 3D Concrete Printing move a step closer to a truly digital fabrication process.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68366369","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 : 2021-01-01DOI: 10.21809/rilemtechlett.2021.131
D. Vizzari, E. Gennesseaux, Stéphane Lavaud, Stéphane Bouron, E. Chailleux
The world energy consumption is constantly increasing and the research point towards novel energy harvesting technologies. In the field of pavement engineering, the exploitable sources are the solar radiation and the vehicle load. At present, these systems are able to convert the sunlight into electricity thanks to some solar cells placed under a semi-transparent layer (photovoltaic roads), or they can harvest thermal heat by means of solar thermal systems. The thermal gradient of the pavement can be exploited by thermoelectric generators, by heat pipes or by heat-transfer fluids (i.e. water) pumped into a medium (asphalt solar collectors, porous layer or air conduits). The traffic load can be exploited by piezoelectric materials, able to convert the vehicle load into an electrical charge. The aim of this paper is to describe the main pavement energy harvesting technologies, pointing out positives and negatives and providing indications for further optimizations. Finally, the systems are compared in terms of initial cost, electrical output, efficiency and technology readiness level.
{"title":"Pavement energy harvesting technologies: a critical review","authors":"D. Vizzari, E. Gennesseaux, Stéphane Lavaud, Stéphane Bouron, E. Chailleux","doi":"10.21809/rilemtechlett.2021.131","DOIUrl":"https://doi.org/10.21809/rilemtechlett.2021.131","url":null,"abstract":"The world energy consumption is constantly increasing and the research point towards novel energy harvesting technologies. In the field of pavement engineering, the exploitable sources are the solar radiation and the vehicle load. At present, these systems are able to convert the sunlight into electricity thanks to some solar cells placed under a semi-transparent layer (photovoltaic roads), or they can harvest thermal heat by means of solar thermal systems. The thermal gradient of the pavement can be exploited by thermoelectric generators, by heat pipes or by heat-transfer fluids (i.e. water) pumped into a medium (asphalt solar collectors, porous layer or air conduits). The traffic load can be exploited by piezoelectric materials, able to convert the vehicle load into an electrical charge. The aim of this paper is to describe the main pavement energy harvesting technologies, pointing out positives and negatives and providing indications for further optimizations. Finally, the systems are compared in terms of initial cost, electrical output, efficiency and technology readiness level.","PeriodicalId":36420,"journal":{"name":"RILEM Technical Letters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68365854","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}
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