This work investigated the formwork surface characteristics and concrete surface quality. The results showed, release agent types and formwork materials have a great impact on the wettability of formwork/concrete interface, although all the formwork surfaces with/without release agents are hydrophilic. Remarkably inhomogeneous roughness characteristic is only announced with steel formwork. Plywood and steel formworks have almost the same roughness values, however roughness profile of plywood is sharper than it of steel. Mineral oil always correlates to larger surface voids and higher surface void ratio (SVR) values. Steel formwork increases SVR significantly compared to the other two formworks. When SVR <1‰ and small voids (<500μm) >50%, the concrete surface seems to be bughole-free. Rusty stains left by steel formwork aggravates concrete discoloration degree, especially when water-soluble release agents were applied. To improve concrete surface quality, plywood formwork is more favorable despite release agents and vegetable oil based emulsion is more suitable for plastic formwork. The surface area roughness of concretes is mainly determined by it of formworks. The typical micro-groove feature on formwork surface leaves no trace on the formed concrete surface which might be due to the dimension difference between micro-grooves and cement particles and the presence of release agents.
{"title":"Effect of typical formworks and release agents on the aesthetical surface quality of concrete","authors":"Jiang Qian, Yu Cheng, Maixi Zhou","doi":"10.1680/jmacr.23.00063","DOIUrl":"https://doi.org/10.1680/jmacr.23.00063","url":null,"abstract":"This work investigated the formwork surface characteristics and concrete surface quality. The results showed, release agent types and formwork materials have a great impact on the wettability of formwork/concrete interface, although all the formwork surfaces with/without release agents are hydrophilic. Remarkably inhomogeneous roughness characteristic is only announced with steel formwork. Plywood and steel formworks have almost the same roughness values, however roughness profile of plywood is sharper than it of steel. Mineral oil always correlates to larger surface voids and higher surface void ratio (SVR) values. Steel formwork increases SVR significantly compared to the other two formworks. When SVR <1‰ and small voids (<500μm) >50%, the concrete surface seems to be bughole-free. Rusty stains left by steel formwork aggravates concrete discoloration degree, especially when water-soluble release agents were applied. To improve concrete surface quality, plywood formwork is more favorable despite release agents and vegetable oil based emulsion is more suitable for plastic formwork. The surface area roughness of concretes is mainly determined by it of formworks. The typical micro-groove feature on formwork surface leaves no trace on the formed concrete surface which might be due to the dimension difference between micro-grooves and cement particles and the presence of release agents.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49019446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The damage and deformation of the cast-in-situ concrete joint between the precast concrete track slabs of the China Railway Track System (CRTS) II is crucial to the safe operation of high-speed railways. To investigate the damage and deformation evolution of the joint concrete under thermal action caused by the natural meteorological environment and vehicle loads, this paper develops a two-dimensional coupled thermal-mechanical numerical model of the concrete joint at mesoscale, which analyzes the influence of three factors; i.e., concrete strength, joint concrete aggregate maximum diameter and vehicle speed. First, the meteorology and heat transfer theory are introduced to the thermal simulations. Then, nonlinear characteristic of the joint concrete is modelled by the two-phase composite material based on the ‘random aggregate algorithm’ and strain-based elastic damage theory at mesoscale. Cohesive zone model (CZM) is utilized to simulate the interfaces between precast slabs. Finally, the reliability of the proposed model is confirmed by the validation study using field measurements. From the results of the numerical example, the maximum aggregate diameter of the joint concrete significantly affects the damage evolution of the joint concrete, and concrete strength has slight effects on the joint uplifting.
{"title":"Mesoscale modelling of CRTS II slab tracks subjected to thermal action and vehicle loads","authors":"H. Chen, Wen-Bin Li, Yu Jiang","doi":"10.1680/jmacr.23.00083","DOIUrl":"https://doi.org/10.1680/jmacr.23.00083","url":null,"abstract":"The damage and deformation of the cast-in-situ concrete joint between the precast concrete track slabs of the China Railway Track System (CRTS) II is crucial to the safe operation of high-speed railways. To investigate the damage and deformation evolution of the joint concrete under thermal action caused by the natural meteorological environment and vehicle loads, this paper develops a two-dimensional coupled thermal-mechanical numerical model of the concrete joint at mesoscale, which analyzes the influence of three factors; i.e., concrete strength, joint concrete aggregate maximum diameter and vehicle speed. First, the meteorology and heat transfer theory are introduced to the thermal simulations. Then, nonlinear characteristic of the joint concrete is modelled by the two-phase composite material based on the ‘random aggregate algorithm’ and strain-based elastic damage theory at mesoscale. Cohesive zone model (CZM) is utilized to simulate the interfaces between precast slabs. Finally, the reliability of the proposed model is confirmed by the validation study using field measurements. From the results of the numerical example, the maximum aggregate diameter of the joint concrete significantly affects the damage evolution of the joint concrete, and concrete strength has slight effects on the joint uplifting.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41549630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Concrete remains a widely used material in construction. As structures become more optimized, a deeper understanding of the rheology of the concrete mixture is necessary. This paper aims to numerically simulate the flow of fresh concrete in the L-box apparatus, with the objective of gaining insights into its rheological behavior and predicting its properties. The fresh concrete flowing through the L-Box test is simulated from the moment that the gate is lifted until the stoppage and the material takes its final shape. The flow in this tool occurs on a free surface. In this work, a three-dimensional model has been developed using the computational fluid dynamics (CFD) technique for simulation. The flow behavior of fresh concrete was assumed to be non-Newtonian following the Bingham law, characterized by a non-linear shear-strain rate ratio, yield stress, and plastic viscosity. A set of numerical simulations by varying workability were conducted. Furthermore, a parametric study was conducted to examine the impact of introduced parameters in the concrete flow, including the effect of yield stress, viscosity, and density.
{"title":"Numerical simulations of fresh concrete flow in the L-Box test using CFD","authors":"Raoudha Sassi, A. Jelidi, S. Montassar","doi":"10.1680/jmacr.23.00032","DOIUrl":"https://doi.org/10.1680/jmacr.23.00032","url":null,"abstract":"Concrete remains a widely used material in construction. As structures become more optimized, a deeper understanding of the rheology of the concrete mixture is necessary. This paper aims to numerically simulate the flow of fresh concrete in the L-box apparatus, with the objective of gaining insights into its rheological behavior and predicting its properties. The fresh concrete flowing through the L-Box test is simulated from the moment that the gate is lifted until the stoppage and the material takes its final shape. The flow in this tool occurs on a free surface. In this work, a three-dimensional model has been developed using the computational fluid dynamics (CFD) technique for simulation. The flow behavior of fresh concrete was assumed to be non-Newtonian following the Bingham law, characterized by a non-linear shear-strain rate ratio, yield stress, and plastic viscosity. A set of numerical simulations by varying workability were conducted. Furthermore, a parametric study was conducted to examine the impact of introduced parameters in the concrete flow, including the effect of yield stress, viscosity, and density.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43070948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bamboo is a naturally sustainable material that has been used in construction for a very long time. Investigations have been carried out by various researchers on the feasibility of using bamboo for reinforcing concrete. However, the lack of construction codes and design procedures for bamboo reinforced concrete (BRC) structures is preventing structural engineers and construction firms from using bamboo in construction. Hence the present study reviews various BRC structural elements including beams, columns, slabs and walls so as to propose guidelines for using them confidently.
{"title":"State of the art review of bamboo reinforced concrete structural elements","authors":"P. Himasree, C. Korde, R. West, N. Ganesan","doi":"10.1680/jmacr.23.00050","DOIUrl":"https://doi.org/10.1680/jmacr.23.00050","url":null,"abstract":"Bamboo is a naturally sustainable material that has been used in construction for a very long time. Investigations have been carried out by various researchers on the feasibility of using bamboo for reinforcing concrete. However, the lack of construction codes and design procedures for bamboo reinforced concrete (BRC) structures is preventing structural engineers and construction firms from using bamboo in construction. Hence the present study reviews various BRC structural elements including beams, columns, slabs and walls so as to propose guidelines for using them confidently.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49198197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Studies on the punching shear of reinforced concrete (RC) slabs exposed to fire are very limited. To address this shortcoming, a series of numerical analyses were carried out to study the effects of several parameters on punching shear behaviour of RC slabs under fire conditions. Variables of the study were: (i) gravity load levels before exposure to fire; (ii) presence or absence of shear reinforcement; (iii) duration of fire (at 30 min intervals), (iv) direction of fire (top and bottom face of slab); and (v) thermal conductivity limits. For this purpose, first, the shear response of a slab–column assembly failing in brittle punching shear under ambient temperature, chosen from the literature, was captured and, subsequently, sequential coupled thermomechanical analyses were carried out using the finite-element software ATENA. Results of the study show that the direction of fire significantly affects the deformation pattern and punching resistance of RC slabs; thermal conductivity plays a minimal role in this regard. Exposure to fire causes the reinforcements to yield at load levels well below the failure load. Finally, shear reinforcement has almost no effect on fire resistance of RC slabs. It is concluded that it is acceptable to ignore shear reinforcements in fire design of RC slabs.
{"title":"Numerical simulation of punching shear in RC slabs subjected to elevated temperatures","authors":"Hamed Sadaghian, Seyed Saeed Mirrezaei, Masood Farzam","doi":"10.1680/jmacr.22.00350","DOIUrl":"https://doi.org/10.1680/jmacr.22.00350","url":null,"abstract":"Studies on the punching shear of reinforced concrete (RC) slabs exposed to fire are very limited. To address this shortcoming, a series of numerical analyses were carried out to study the effects of several parameters on punching shear behaviour of RC slabs under fire conditions. Variables of the study were: (i) gravity load levels before exposure to fire; (ii) presence or absence of shear reinforcement; (iii) duration of fire (at 30 min intervals), (iv) direction of fire (top and bottom face of slab); and (v) thermal conductivity limits. For this purpose, first, the shear response of a slab–column assembly failing in brittle punching shear under ambient temperature, chosen from the literature, was captured and, subsequently, sequential coupled thermomechanical analyses were carried out using the finite-element software ATENA. Results of the study show that the direction of fire significantly affects the deformation pattern and punching resistance of RC slabs; thermal conductivity plays a minimal role in this regard. Exposure to fire causes the reinforcements to yield at load levels well below the failure load. Finally, shear reinforcement has almost no effect on fire resistance of RC slabs. It is concluded that it is acceptable to ignore shear reinforcements in fire design of RC slabs.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135099425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaoxiao Wang, Yufei Dong, Lei Jing, Changwang Yan, Shuguang Liu
Natural pumice concrete (NPC) is a building material with the advantage of lightweight, high thermal resistance. In cold regions, NPC has to face the damage from freeze-thaw cycles. Freeze-thaw damage is closely related to changes in the pore structure of concrete. Therefore, it is meaningful to investigate evolution characteristics and damage threshold of pore structure for NPC under freeze-thaw cycles. In this study, freeze-thaw cycles tests, nuclear magnetic resonance (NMR) tests were designed. The characteristics of the evolution of the pore structure during freeze-thaw cycles were discussed. The results showed that the porosity in NPC specimens increases with the number of freeze-thaw cycles, and the main evolution of the pores showed the degradation of fine capillary pores (10nm1000 nm). After freeze-thaw cycles, the proportion of coarse capillary pores and non-capillary pores increased by 4.83%-10.59%. This evolutionary feature will directly lead to the degradation of the mechanical properties of NPC. Additionally, a pore damage model was established, and the pore damage threshold was also calculated based on the experimental results. The obtained damage threshold of pore structure can provide the theoretical foundation for the application of NPC in cold regions.
{"title":"Evolution and damage threshold of pores for natural pumice concrete under freeze-thaw cycles","authors":"Xiaoxiao Wang, Yufei Dong, Lei Jing, Changwang Yan, Shuguang Liu","doi":"10.1680/jmacr.22.00335","DOIUrl":"https://doi.org/10.1680/jmacr.22.00335","url":null,"abstract":"Natural pumice concrete (NPC) is a building material with the advantage of lightweight, high thermal resistance. In cold regions, NPC has to face the damage from freeze-thaw cycles. Freeze-thaw damage is closely related to changes in the pore structure of concrete. Therefore, it is meaningful to investigate evolution characteristics and damage threshold of pore structure for NPC under freeze-thaw cycles. In this study, freeze-thaw cycles tests, nuclear magnetic resonance (NMR) tests were designed. The characteristics of the evolution of the pore structure during freeze-thaw cycles were discussed. The results showed that the porosity in NPC specimens increases with the number of freeze-thaw cycles, and the main evolution of the pores showed the degradation of fine capillary pores (10nm1000 nm). After freeze-thaw cycles, the proportion of coarse capillary pores and non-capillary pores increased by 4.83%-10.59%. This evolutionary feature will directly lead to the degradation of the mechanical properties of NPC. Additionally, a pore damage model was established, and the pore damage threshold was also calculated based on the experimental results. The obtained damage threshold of pore structure can provide the theoretical foundation for the application of NPC in cold regions.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44629513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The high specific density of concrete significantly increases the dead load in buildings. Preferring the aggregate used in concrete as pumice, which is a volcanic material, decreases the concrete's density. However, pumice causes a decrease in the mechanical properties of concrete due to its pores structure. The improvement of the mechanical properties of concrete provides material savings by reducing the cross-sections of the structural elements to be used in buildings. Ultra-high-performance concrete, which has been an important subject of studies in recent years, is an important construction material for civil engineering. In this study, fresh concrete, physical and mechanical properties of lightweight ultra-high-performance concrete (LW-UHPC) with pumice additive were investigated. Nano carbon black was added to the mixture as 5, 10 and 15% of the cement weight. Significant increases were observed in the mechanical properties of nano carbon black added concrete. The addition of nanocarbon black to concrete at a certain ratio increased the compressive strength and flexural strength of concrete by 9.9% and 10.6%, respectively. In addition, it was observed that the sulphate resistance increased in direct proportion to the increase in the amount of nanocarbon black.
{"title":"Investigation of physical and mechanical properties of nano carbon black added lightweight UHPC","authors":"M. Uzun","doi":"10.1680/jmacr.23.00025","DOIUrl":"https://doi.org/10.1680/jmacr.23.00025","url":null,"abstract":"The high specific density of concrete significantly increases the dead load in buildings. Preferring the aggregate used in concrete as pumice, which is a volcanic material, decreases the concrete's density. However, pumice causes a decrease in the mechanical properties of concrete due to its pores structure. The improvement of the mechanical properties of concrete provides material savings by reducing the cross-sections of the structural elements to be used in buildings. Ultra-high-performance concrete, which has been an important subject of studies in recent years, is an important construction material for civil engineering. In this study, fresh concrete, physical and mechanical properties of lightweight ultra-high-performance concrete (LW-UHPC) with pumice additive were investigated. Nano carbon black was added to the mixture as 5, 10 and 15% of the cement weight. Significant increases were observed in the mechanical properties of nano carbon black added concrete. The addition of nanocarbon black to concrete at a certain ratio increased the compressive strength and flexural strength of concrete by 9.9% and 10.6%, respectively. In addition, it was observed that the sulphate resistance increased in direct proportion to the increase in the amount of nanocarbon black.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47878880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A number of regression-based models have been proposed to quantify the seismic shear strength of reinforced concrete (RC) columns. However, most of these models suffer from a high degree of uncertainty as a result of the limited datasets used in the development and/or the classic approaches used to capture the nonlinear interrelationships between the shear strength and influencing factors. To address these issues, this study harnesses the power of multi-gene genetic programming (MGGP), guided by mechanics, to identify the primary influencing factors and subsequently develop efficient shear capacity predictive models for rectangular and circular RC columns. Published comprehensive datasets for the shear strength of cyclically-loaded RC columns were compiled and employed to develop the MGGP-based models. The efficiency of the developed models was assessed, and their performances were also compared with that of relevant existing predictive models. The results demonstrated the ability of the mechanics-guided MGGP approach to produce more accurate and conssistant predictive models, compared to those available in relevant design standards and literature, that can describe the complex shear behavior of RC columns under cyclic loading.
{"title":"Evolutionary computing-based models for predicting seismic shear strength of RC columns","authors":"Mohamed K. Ismail, A. Yosri, W. El-Dakhakhni","doi":"10.1680/jmacr.23.00043","DOIUrl":"https://doi.org/10.1680/jmacr.23.00043","url":null,"abstract":"A number of regression-based models have been proposed to quantify the seismic shear strength of reinforced concrete (RC) columns. However, most of these models suffer from a high degree of uncertainty as a result of the limited datasets used in the development and/or the classic approaches used to capture the nonlinear interrelationships between the shear strength and influencing factors. To address these issues, this study harnesses the power of multi-gene genetic programming (MGGP), guided by mechanics, to identify the primary influencing factors and subsequently develop efficient shear capacity predictive models for rectangular and circular RC columns. Published comprehensive datasets for the shear strength of cyclically-loaded RC columns were compiled and employed to develop the MGGP-based models. The efficiency of the developed models was assessed, and their performances were also compared with that of relevant existing predictive models. The results demonstrated the ability of the mechanics-guided MGGP approach to produce more accurate and conssistant predictive models, compared to those available in relevant design standards and literature, that can describe the complex shear behavior of RC columns under cyclic loading.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47702820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Carbon sequestration in cement-based materials has emerged as one of the promising avenues to utilize captured carbon dioxide (CO2) and reduce the carbon footprint of the concrete industry. This article presents a comprehensive review of various studies conducted in this domain with a particular emphasis on factors affecting the carbon uptake potential of various concrete types and the effect of carbonation on the critical properties of concretes. Studies conducted on Carbon Sequestered Concrete's (CSC's) micro-mechanical analysis show that carbonation significantly improved the microhardness of the concrete samples, thereby increasing the strength and reducing the cement intake requirement. Further, keeping two parameters, namely, the ratio of water-to-solid (w/s) along with carbonation reaction time in focus, the CO2 uptaking capacity in concrete slurry waste (CSW) was evaluated using non-linear regression analysis. It was observed that CSW paste had a maximum CO2 uptake with an intermediate w/s ratio of 0.2 due to CO2 reaction hindrances during diffusion at a higher w/s ratio and lack of hydration at a lower w/s ratio. On the contrary, for belite-rich cement, a higher w/s ratio led to higher CO2 uptake owing to belite phase consumption leading to increased calcite production. Additionally, comparing the CO2 maximum uptake capacity of CSW at a particular condition with various other cement-based materials, it was observed that belite-rich cement had the ability to sequester the maximum amount of CO2 out of other cement-based materials considered in this study. Highlights: (1) CSW paste made of a w/s ratio of 0.2 and carbonated for 600 hours could achieve a CO2 uptake capacity of 20%. (2) Belite-rich cement and nano-TiO2-added cement had the highest and the lowest CO2 uptake capacity, respectively, with CSW lying in the middle, which is preceded and succeeded by limestone-added cement and Ordinary Portland Cement (OPC) cement.
{"title":"Understanding the captured CO2 utilisation potential of various cementitious materials through review and analytical modelling","authors":"Sowrav Saikia, Aditya S. Rajput","doi":"10.1680/jmacr.22.00313","DOIUrl":"https://doi.org/10.1680/jmacr.22.00313","url":null,"abstract":"Carbon sequestration in cement-based materials has emerged as one of the promising avenues to utilize captured carbon dioxide (CO2) and reduce the carbon footprint of the concrete industry. This article presents a comprehensive review of various studies conducted in this domain with a particular emphasis on factors affecting the carbon uptake potential of various concrete types and the effect of carbonation on the critical properties of concretes. Studies conducted on Carbon Sequestered Concrete's (CSC's) micro-mechanical analysis show that carbonation significantly improved the microhardness of the concrete samples, thereby increasing the strength and reducing the cement intake requirement. Further, keeping two parameters, namely, the ratio of water-to-solid (w/s) along with carbonation reaction time in focus, the CO2 uptaking capacity in concrete slurry waste (CSW) was evaluated using non-linear regression analysis. It was observed that CSW paste had a maximum CO2 uptake with an intermediate w/s ratio of 0.2 due to CO2 reaction hindrances during diffusion at a higher w/s ratio and lack of hydration at a lower w/s ratio. On the contrary, for belite-rich cement, a higher w/s ratio led to higher CO2 uptake owing to belite phase consumption leading to increased calcite production. Additionally, comparing the CO2 maximum uptake capacity of CSW at a particular condition with various other cement-based materials, it was observed that belite-rich cement had the ability to sequester the maximum amount of CO2 out of other cement-based materials considered in this study. Highlights: (1) CSW paste made of a w/s ratio of 0.2 and carbonated for 600 hours could achieve a CO2 uptake capacity of 20%. (2) Belite-rich cement and nano-TiO2-added cement had the highest and the lowest CO2 uptake capacity, respectively, with CSW lying in the middle, which is preceded and succeeded by limestone-added cement and Ordinary Portland Cement (OPC) cement.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43402664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present study explores the feasibility of using recycled materials from display glass electronic waste (DGE-waste) in the production of cementitious mortars as a granular corrector for dune sand and as a cementitious addition. The effects of the DGE-waste replacement ratio (5–20% with 5% steps by weight of three types of dune sand from three different regions) on the engineering properties of reinforced cementitious composite were experimentally investigated to assess the performance of dune sand mortar. The results show that the incorporation of DGE-waste in dune sand mortar can increase the mechanical strengths (flexural and compressive) by up to 35% and 43%, respectively, and improve the dynamic modulus of elasticity by at most 12% as compared with the control mortar, as well as decrease open porosity by up to 28%, which reduces micro-cracks and voids. When cement is replaced with 15% recycled DGE-waste, the mechanical strength and dynamic modulus of elasticity, as well as open porosity and absorption, are decreased by 4–7% and 17–20%, respectively. Considering the environmental impact and engineering properties, the optimal percentage of DGE-waste incorporation is 15% for cement replacement and 20% for dune sand replacement.
{"title":"Influence of recycled display glass e-waste on ternary dune sand mortar engineering properties","authors":"Choungara Toufik, A. Ghrieb, Y. Abadou","doi":"10.1680/jmacr.22.00316","DOIUrl":"https://doi.org/10.1680/jmacr.22.00316","url":null,"abstract":"The present study explores the feasibility of using recycled materials from display glass electronic waste (DGE-waste) in the production of cementitious mortars as a granular corrector for dune sand and as a cementitious addition. The effects of the DGE-waste replacement ratio (5–20% with 5% steps by weight of three types of dune sand from three different regions) on the engineering properties of reinforced cementitious composite were experimentally investigated to assess the performance of dune sand mortar. The results show that the incorporation of DGE-waste in dune sand mortar can increase the mechanical strengths (flexural and compressive) by up to 35% and 43%, respectively, and improve the dynamic modulus of elasticity by at most 12% as compared with the control mortar, as well as decrease open porosity by up to 28%, which reduces micro-cracks and voids. When cement is replaced with 15% recycled DGE-waste, the mechanical strength and dynamic modulus of elasticity, as well as open porosity and absorption, are decreased by 4–7% and 17–20%, respectively. Considering the environmental impact and engineering properties, the optimal percentage of DGE-waste incorporation is 15% for cement replacement and 20% for dune sand replacement.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":" ","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48773579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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