Pub Date : 2024-01-01DOI: 10.1680/jmacr.2024.76.2.108
{"title":"Award-winning paper in 2022","authors":"","doi":"10.1680/jmacr.2024.76.2.108","DOIUrl":"https://doi.org/10.1680/jmacr.2024.76.2.108","url":null,"abstract":"","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"139 23","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139128381","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}
Reza Saghafi Lasemi, Masoud Ziaei, Mohammad Hadi Alizadeh Elizei, Reza Esmaeil Abadi
One of the recycling approaches of waste materials like tires and glass is to use them in concrete. In this paper, the effect of simultaneous use of waste rubber and glass powder, as partial substitution of fine aggregate and cement, on workability and mechanical properties in ambient temperature and after exposure to temperature of 600°C is investigated. In total, 13 mixtures were prepared. Except the reference mixture, the rest contained a combination of rubber particles replacing fine aggregate with the percentages of 5% and 10% by volume and glass powder replacing cement with percentages of 10%, 15% and 20%. First of all, the slump test was carried out. Moreover, compressive strength, tensile strength and ratio of tensile to compressive strength, before and after thermal exposure, and mass loss after exposure to elevated temperature were investigated. In order to have an understanding of waste materials behaviour, scanning electron microscopy and energy-dispersive X-ray spectroscopy tests were conducted. the results indicated that 5% for rubber particles, 10% for glass powder and also rubber particle size of 3-5mm presented the best results among mixtures containing rubber and glass powder, in terms of compressive and tensile strengths.
{"title":"Mechanical and thermal behavior of concrete including waste tire and glass powder as fine aggregate and cement respectively","authors":"Reza Saghafi Lasemi, Masoud Ziaei, Mohammad Hadi Alizadeh Elizei, Reza Esmaeil Abadi","doi":"10.1680/jmacr.23.00115","DOIUrl":"https://doi.org/10.1680/jmacr.23.00115","url":null,"abstract":"One of the recycling approaches of waste materials like tires and glass is to use them in concrete. In this paper, the effect of simultaneous use of waste rubber and glass powder, as partial substitution of fine aggregate and cement, on workability and mechanical properties in ambient temperature and after exposure to temperature of 600°C is investigated. In total, 13 mixtures were prepared. Except the reference mixture, the rest contained a combination of rubber particles replacing fine aggregate with the percentages of 5% and 10% by volume and glass powder replacing cement with percentages of 10%, 15% and 20%. First of all, the slump test was carried out. Moreover, compressive strength, tensile strength and ratio of tensile to compressive strength, before and after thermal exposure, and mass loss after exposure to elevated temperature were investigated. In order to have an understanding of waste materials behaviour, scanning electron microscopy and energy-dispersive X-ray spectroscopy tests were conducted. the results indicated that 5% for rubber particles, 10% for glass powder and also rubber particle size of 3-5mm presented the best results among mixtures containing rubber and glass powder, in terms of compressive and tensile strengths.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"22 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139052727","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}
This paper provides a comprehensive overview of fracture propagation in concrete, covering various aspects ranging from fundamentals to applications and future directions. The introduction section presents an overview of fracture propagation in concrete, emphasising its importance in understanding the behaviour of concrete structures. The fundamentals of fracture propagation are explored, including concrete as a composite material, crack initiation and propagation mechanisms, types of fractures and factors influencing fracture propagation. Experimental techniques for studying fracture propagation are discussed, encompassing both non-destructive and destructive testing methods, such as acoustic emission, ultrasonic testing, digital image correlation and advanced imaging techniques like X-ray tomography and scanning electron microscopy. Modelling approaches, including continuum damage mechanics, finite element method, discrete element method, lattice discrete particle model and hybrid modelling approaches, are reviewed for simulating and predicting fracture propagation behaviour. The applications of fracture propagation in concrete are highlighted, including structural health monitoring, design optimisation, failure analysis and repair and rehabilitation strategies. The research opportunities for further improvement are addressed. The paper serves as a valuable resource for researchers, engineers and professionals in the field, providing a comprehensive understanding of fracture propagation in concrete and guiding future research endeavours.
本文全面概述了混凝土中的断裂扩展，涵盖了从基础到应用以及未来发展方向等各个方面。引言部分概述了混凝土中的断裂扩展，强调了其对理解混凝土结构行为的重要性。书中探讨了断裂扩展的基本原理，包括作为复合材料的混凝土、裂纹的产生和扩展机制、断裂类型以及影响断裂扩展的因素。还讨论了研究断裂扩展的实验技术，包括非破坏性和破坏性测试方法，如声发射、超声波测试、数字图像关联以及 X 射线断层扫描和扫描电子显微镜等先进成像技术。对模拟和预测断裂扩展行为的建模方法进行了综述，包括连续损伤力学、有限元法、离散元法、晶格离散粒子模型和混合建模方法。重点介绍了混凝土断裂扩展的应用，包括结构健康监测、设计优化、失效分析以及修复和复原策略。还探讨了进一步改进的研究机会。论文为该领域的研究人员、工程师和专业人士提供了宝贵的资源，使他们对混凝土断裂扩展有了全面的了解，并为未来的研究工作提供了指导。
{"title":"A review on fracture propagation in concrete: fundamentals, experimental techniques, modelling and applications","authors":"Salim Barbhuiya, Bibhuti Bhusan Das, Fragkoulis Kanavaris","doi":"10.1680/jmacr.23.00143","DOIUrl":"https://doi.org/10.1680/jmacr.23.00143","url":null,"abstract":"This paper provides a comprehensive overview of fracture propagation in concrete, covering various aspects ranging from fundamentals to applications and future directions. The introduction section presents an overview of fracture propagation in concrete, emphasising its importance in understanding the behaviour of concrete structures. The fundamentals of fracture propagation are explored, including concrete as a composite material, crack initiation and propagation mechanisms, types of fractures and factors influencing fracture propagation. Experimental techniques for studying fracture propagation are discussed, encompassing both non-destructive and destructive testing methods, such as acoustic emission, ultrasonic testing, digital image correlation and advanced imaging techniques like X-ray tomography and scanning electron microscopy. Modelling approaches, including continuum damage mechanics, finite element method, discrete element method, lattice discrete particle model and hybrid modelling approaches, are reviewed for simulating and predicting fracture propagation behaviour. The applications of fracture propagation in concrete are highlighted, including structural health monitoring, design optimisation, failure analysis and repair and rehabilitation strategies. The research opportunities for further improvement are addressed. The paper serves as a valuable resource for researchers, engineers and professionals in the field, providing a comprehensive understanding of fracture propagation in concrete and guiding future research endeavours.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"15 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139052644","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}
Mizan Ahmed, Saad A. Yehia, Ramy I. Shahin, Mohamed Emara, Vipulkumar Ishvarbhai Patel, Qing Quan Liang
This paper presents a computational model for determining the axial responses of circular Steel-Reinforced Concrete-Filled Steel Tubular (SRCFST) short columns. A novel confinement model is formulated for the concrete-core that is effectively confined by the external circular steel tube and the embedded steel section. The modeling scheme of confinement is programmed in the mathematical model that utilizes the fiber element discretization of column cross-sections. The numerical predictions are verified by experimental measurements and results obtained from the finite element analysis, demonstrating the accuracy of the modeling technology. In addition, existing concrete confinement models for concrete in circular Concrete-Filled Steel Tubular (CFST) columns are assessed. The new confinement model is shown to be superior in replicating the responses of SRCFST columns. The influences of design parameters on the column's performance are numerically investigated and the importance order of these parameters is determined by a sensitivity analysis. The study not only examines the validity of current design standards in determining the axial load capacity of SRCFST columns but also proposes a new design formula. The proposed confinement model can be employed in numerical procedures for the inelastic simulation of SRCFST columns and the design formula is suitable for use in practical design.
{"title":"Numerical simulation and design of circular steel-reinforced concrete-filled steel tubular short columns under axial loading","authors":"Mizan Ahmed, Saad A. Yehia, Ramy I. Shahin, Mohamed Emara, Vipulkumar Ishvarbhai Patel, Qing Quan Liang","doi":"10.1680/jmacr.23.00153","DOIUrl":"https://doi.org/10.1680/jmacr.23.00153","url":null,"abstract":"This paper presents a computational model for determining the axial responses of circular Steel-Reinforced Concrete-Filled Steel Tubular (SRCFST) short columns. A novel confinement model is formulated for the concrete-core that is effectively confined by the external circular steel tube and the embedded steel section. The modeling scheme of confinement is programmed in the mathematical model that utilizes the fiber element discretization of column cross-sections. The numerical predictions are verified by experimental measurements and results obtained from the finite element analysis, demonstrating the accuracy of the modeling technology. In addition, existing concrete confinement models for concrete in circular Concrete-Filled Steel Tubular (CFST) columns are assessed. The new confinement model is shown to be superior in replicating the responses of SRCFST columns. The influences of design parameters on the column's performance are numerically investigated and the importance order of these parameters is determined by a sensitivity analysis. The study not only examines the validity of current design standards in determining the axial load capacity of SRCFST columns but also proposes a new design formula. The proposed confinement model can be employed in numerical procedures for the inelastic simulation of SRCFST columns and the design formula is suitable for use in practical design.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"11 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138818579","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}
Ultra-high-performance concrete (UHPC) is susceptible to various forms of abrasion during its service life. This study investigates the abrasion resistance of UHPC by focusing on two primary causes of wear: traffic dynamic loads and hydraulic impacts. To enhance the material's resistance to abrasion, milling steel fibers were utilized, and for comparative purposes, straight steel fibers and hybrid milling-straight steel fibers were also employed. The protective function of the steel fibers primarily comes into effect once the concrete cover has experienced wear. When subjected to traffic and hydraulic loads, UHPC containing milling fibers exhibited superior resistance compared to that containing straight fibers, while maintaining favorable workability. Notably, the UHPC incorporating hybrid steel fibers, which form a composite skeleton due to the presence of two fiber types, demonstrated even greater effectiveness in resisting external abrasion. Furthermore, the abrasion resistances observed under both traffic and hydraulic conditions displayed a positive linear correlation with an R2 value exceeding 0.8. These findings suggest the feasibility of evaluating the material's abrasion resistance under various wearing causes using a single test method. The outcomes of this study hold promise in advancing the development of UHPC and promoting its utilization in conditions characterized by severe abrasion.
{"title":"Abrasion resistance of milling steel fiber-reinforced ultra-high-performance concrete under various wearing conditions","authors":"Hengchang Wang, Baixi Chen, Yibo Yang, Yinggan Xia, Qifeng Xiao, Shaokun Liu, Wenying Guo","doi":"10.1680/jmacr.23.00236","DOIUrl":"https://doi.org/10.1680/jmacr.23.00236","url":null,"abstract":"Ultra-high-performance concrete (UHPC) is susceptible to various forms of abrasion during its service life. This study investigates the abrasion resistance of UHPC by focusing on two primary causes of wear: traffic dynamic loads and hydraulic impacts. To enhance the material's resistance to abrasion, milling steel fibers were utilized, and for comparative purposes, straight steel fibers and hybrid milling-straight steel fibers were also employed. The protective function of the steel fibers primarily comes into effect once the concrete cover has experienced wear. When subjected to traffic and hydraulic loads, UHPC containing milling fibers exhibited superior resistance compared to that containing straight fibers, while maintaining favorable workability. Notably, the UHPC incorporating hybrid steel fibers, which form a composite skeleton due to the presence of two fiber types, demonstrated even greater effectiveness in resisting external abrasion. Furthermore, the abrasion resistances observed under both traffic and hydraulic conditions displayed a positive linear correlation with an R<sup>2</sup> value exceeding 0.8. These findings suggest the feasibility of evaluating the material's abrasion resistance under various wearing causes using a single test method. The outcomes of this study hold promise in advancing the development of UHPC and promoting its utilization in conditions characterized by severe abrasion.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"67 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138818307","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}
Zahir Azimi, Moein Mousavi, Habib Akbarzadeh Bengar, Akbar A. Javadi
Along with the rise in construction with 3D printing technology, 3D printed (3DP) structures also require weight reduction similar to conventional reinforcement concrete (RC) structures. In addition, the behaviour of this type of structure against fire needs to be investigated. The number of printed layers and the time gap between layers for the 3DP specimens were among the variables examined in the tests. The test results demonstrated that as the replacement percentage of natural sand (NS) with expanded perlite (EP) increased, at 25% volume of replacement the interlayer bond strength increased on average by 18.6%, while at the highest replacement level of 75%, decreased on average by 5.8%. Additionally, by incorporation of EP the compressive and flexural strengths of 3DP specimens declined averagely from 9% to 29.7%, and 39.3% to 49.3%, respectively. As the replacement level of NS increased, residual compressive and flexural strengths increased after exposure to 800 °C. Furthermore, it was demonstrated that exposure to high temperature had the least effect on interlayer bond strength, whereas it significantly reduced the compressive and flexural strength. The results showed that, increasing the time gap between layers reduced interlayer bond strength and flexural strength while negligibly affected compressive strength.
随着 3D 打印技术在建筑领域的应用，3D 打印（3DP）结构也需要与传统钢筋混凝土（RC）结构一样减轻重量。此外，还需要研究这类结构的防火性能。3DP 试样的打印层数和层与层之间的时间间隔是测试中的变量之一。试验结果表明，随着膨胀珍珠岩（EP）对天然砂（NS）替代比例的增加，在替代量为 25% 时，层间粘结强度平均增加了 18.6%，而在最高替代水平 75% 时，平均降低了 5.8%。此外，加入 EP 后，3DP 试样的抗压和抗弯强度平均分别从 9% 下降到 29.7%，从 39.3% 下降到 49.3%。随着 NS 替代水平的提高，暴露于 800 °C 后的残余抗压强度和抗折强度也有所提高。此外，高温暴露对层间结合强度的影响最小，但会显著降低抗压和抗折强度。结果表明，增加层间时间间隔会降低层间结合强度和抗折强度，而对抗压强度的影响可以忽略不计。
{"title":"Study on the post-fire mechanical properties of lightweight 3D printed concrete containing expanded perlite as partial replacement of natural sand","authors":"Zahir Azimi, Moein Mousavi, Habib Akbarzadeh Bengar, Akbar A. Javadi","doi":"10.1680/jmacr.23.00159","DOIUrl":"https://doi.org/10.1680/jmacr.23.00159","url":null,"abstract":"Along with the rise in construction with 3D printing technology, 3D printed (3DP) structures also require weight reduction similar to conventional reinforcement concrete (RC) structures. In addition, the behaviour of this type of structure against fire needs to be investigated. The number of printed layers and the time gap between layers for the 3DP specimens were among the variables examined in the tests. The test results demonstrated that as the replacement percentage of natural sand (NS) with expanded perlite (EP) increased, at 25% volume of replacement the interlayer bond strength increased on average by 18.6%, while at the highest replacement level of 75%, decreased on average by 5.8%. Additionally, by incorporation of EP the compressive and flexural strengths of 3DP specimens declined averagely from 9% to 29.7%, and 39.3% to 49.3%, respectively. As the replacement level of NS increased, residual compressive and flexural strengths increased after exposure to 800 °C. Furthermore, it was demonstrated that exposure to high temperature had the least effect on interlayer bond strength, whereas it significantly reduced the compressive and flexural strength. The results showed that, increasing the time gap between layers reduced interlayer bond strength and flexural strength while negligibly affected compressive strength.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"35 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138818538","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 innovative Arc Pressure Testing Method (APTM) is adopted in this study to obtain the strength of in-situ concrete and reduce damage to the concrete structure. This method is related to the double shear plane of the concrete core. A specific APTM apparatus is used to apply loads for obtaining the approximate pure shear stress and shear strength of the concrete core. Factors affecting the strength of concrete, such as aggregate type and concrete moisture, were excluded through experiments. The compressive strength range of the tested cube concrete samples is 20-60MPa. The reliability and repeatability of APTM are superior to in-situ testing techniques such as Schmidt Hammer (SRH) and pull-out testing methods. The experimental results indicate that APTM is suitable for in-situ testing of concrete compressive strength of prefabricated buildings, beam-column joints other dense steel structures. Compared with other testing methods, its accuracy is much higher, and the damage to the structure is minimized.
{"title":"Experimental study on compressive strength of in-situ concrete tested with arc pressure method","authors":"Suhang Yang, Chen Hu, Zhifeng Xu","doi":"10.1680/jmacr.23.00177","DOIUrl":"https://doi.org/10.1680/jmacr.23.00177","url":null,"abstract":"The innovative Arc Pressure Testing Method (APTM) is adopted in this study to obtain the strength of in-situ concrete and reduce damage to the concrete structure. This method is related to the double shear plane of the concrete core. A specific APTM apparatus is used to apply loads for obtaining the approximate pure shear stress and shear strength of the concrete core. Factors affecting the strength of concrete, such as aggregate type and concrete moisture, were excluded through experiments. The compressive strength range of the tested cube concrete samples is 20-60MPa. The reliability and repeatability of APTM are superior to in-situ testing techniques such as Schmidt Hammer (SRH) and pull-out testing methods. The experimental results indicate that APTM is suitable for in-situ testing of concrete compressive strength of prefabricated buildings, beam-column joints other dense steel structures. Compared with other testing methods, its accuracy is much higher, and the damage to the structure is minimized.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"28 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138821749","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}
This paper presents a comparative evaluation of the single and combined effect of nanoparticles on the static and impact properties of concrete. Nano-SiO2, nano-Al2O3 and nano-Fe2O3 were used separately and in combined forms as partial replacements of cement by 1% and 2% by weight. The impact of nanoparticles on the unit weight, compressive strength, split tensile strength, flexural strength, toughness, fracture energy, impact performance of concrete was experimentally examined. In addition, the effect of these nanoparticles on the microstructure of concrete was investigated using SEM analysis. Moreover, to evaluate the commercial production of such concretes, the cost effectiveness of use of nanoparticles in concrete was also discussed. Desirability function analysis was also conducted to compare the overall performance of the tested concretes. The results revealed that use of nano materials in concrete had a positive effect on improving their mechanical performance. Nanoparticles increased the compressive strength, split tensile strength, flexural strength, and energy absorption capacity of concrete. Use of nanoparticles didn't show any significant influence on the unit weight of concrete. Moreover, the results also showed that nano materials didn't have a good influence on the impact performance of concrete. SEM analysis showed that use of nanoparticles improved the microstructure of concrete.
{"title":"Experimental study on static and impact properties of concrete incorporating nano-SiO2, nano-Al2O3 and Fe2O3 in single and combined forms","authors":"Mohammed Gamal Al-Hagri, Mahmud Sami Döndüren","doi":"10.1680/jmacr.23.00156","DOIUrl":"https://doi.org/10.1680/jmacr.23.00156","url":null,"abstract":"This paper presents a comparative evaluation of the single and combined effect of nanoparticles on the static and impact properties of concrete. Nano-SiO<sub>2</sub>, nano-Al<sub>2</sub>O<sub>3</sub> and nano-Fe<sub>2</sub>O<sub>3</sub> were used separately and in combined forms as partial replacements of cement by 1% and 2% by weight. The impact of nanoparticles on the unit weight, compressive strength, split tensile strength, flexural strength, toughness, fracture energy, impact performance of concrete was experimentally examined. In addition, the effect of these nanoparticles on the microstructure of concrete was investigated using SEM analysis. Moreover, to evaluate the commercial production of such concretes, the cost effectiveness of use of nanoparticles in concrete was also discussed. Desirability function analysis was also conducted to compare the overall performance of the tested concretes. The results revealed that use of nano materials in concrete had a positive effect on improving their mechanical performance. Nanoparticles increased the compressive strength, split tensile strength, flexural strength, and energy absorption capacity of concrete. Use of nanoparticles didn't show any significant influence on the unit weight of concrete. Moreover, the results also showed that nano materials didn't have a good influence on the impact performance of concrete. SEM analysis showed that use of nanoparticles improved the microstructure of concrete.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"28 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138818590","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}
This study systematically investigates the superplasticizer (SP) addition methods and optimum SP dosage with various water binder (w/b) ratios for mixing 3D printable concrete (3DPC). In the present study, five distinct strategies were adopted to arrive at the optimum Method of Addition (MoA). The first strategy applied the random mixing approach to identify the methods for adding SP with varying time patterns through visual observation. Secondly, a constant time pattern was adopted from the random approach for mixing and the optimal SP dosage was determined. The third strategy examined different addition methods with the optimum SP dosage. In the fourth strategy, the batching effect of the material with the optimum SP dosage was assessed, and finally, the printable region with different w/b ratios and SP dosages were correlated. The observations illustrated that the optimum SP dosage in the range of 0.10 to 0.21% of binder with a w/b ratio of 0.21 to 0.25 achieved adequate printability parameters by full addition of SP following a constant wet mixing time as the optimal application. However, after applying the optimum SP dosage, a supplemental SP dosage is required at appropriate intervals to retain the workability for higher batches.
{"title":"Mixing approach for 3D printable concrete: method of addition and optimization of superplasticizer dosage","authors":"P.S. Ambily, Senthil Kumar Kaliyavaradhan, Shilpa Sebastian, Deepadharshan Shekar","doi":"10.1680/jmacr.23.00165","DOIUrl":"https://doi.org/10.1680/jmacr.23.00165","url":null,"abstract":"This study systematically investigates the superplasticizer (SP) addition methods and optimum SP dosage with various water binder (w/b) ratios for mixing 3D printable concrete (3DPC). In the present study, five distinct strategies were adopted to arrive at the optimum Method of Addition (MoA). The first strategy applied the random mixing approach to identify the methods for adding SP with varying time patterns through visual observation. Secondly, a constant time pattern was adopted from the random approach for mixing and the optimal SP dosage was determined. The third strategy examined different addition methods with the optimum SP dosage. In the fourth strategy, the batching effect of the material with the optimum SP dosage was assessed, and finally, the printable region with different w/b ratios and SP dosages were correlated. The observations illustrated that the optimum SP dosage in the range of 0.10 to 0.21% of binder with a w/b ratio of 0.21 to 0.25 achieved adequate printability parameters by full addition of SP following a constant wet mixing time as the optimal application. However, after applying the optimum SP dosage, a supplemental SP dosage is required at appropriate intervals to retain the workability for higher batches.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"70 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138688045","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}
Dongyun Liu, Chao Wang, Tong Guo, Jaime Gonzalez-Libreros, Yuanfei Ge, Yongming Tu, Lennart Elfgren, Gabriel Sas
Chloride attack severely impacts the performance of reinforced concrete. The total and free chloride ion concentrations (CICs) of self-compacting concrete (SCC) prepared with three supplementary cementitious materials (SCMs) - fly ash (FA), blast furnace slag (BS), and silica fume (SF) – were measured through the accelerated salt immersion tests. The apparent chloride diffusion coefficients (CDCs) at any exposure time and erosion depth were calculated using the Boltzmann-Matano method. The influence of the type and content of SCMs, the water-binder ratio (W/B), and the type of salt solution on CICs and CDCs were investigated. Both introducing SCMs and reducing W/B effectively reduced the CIC. The SCM that most effectively reduced CIC was SF, followed by BS and then FA. Free CICs were reduced to a greater degree than total CICs in FA and BS concrete, but the opposite was true for SF concrete. Presence of calcium chloride in salt solution increased total CICs while reducing free CICs. Apparent free CDC dropped over exposure time and initially increased with erosion depth but eventually stabilized. A model of apparent free CDC considering the time-depth dependence was created, which shows that time reduction factors of CDC is larger in SCM-containing SCC than in control SCC.
{"title":"Time-depth dependent chloride diffusion coefficients of self-compacting concrete","authors":"Dongyun Liu, Chao Wang, Tong Guo, Jaime Gonzalez-Libreros, Yuanfei Ge, Yongming Tu, Lennart Elfgren, Gabriel Sas","doi":"10.1680/jmacr.23.00237","DOIUrl":"https://doi.org/10.1680/jmacr.23.00237","url":null,"abstract":"Chloride attack severely impacts the performance of reinforced concrete. The total and free chloride ion concentrations (CICs) of self-compacting concrete (SCC) prepared with three supplementary cementitious materials (SCMs) - fly ash (FA), blast furnace slag (BS), and silica fume (SF) – were measured through the accelerated salt immersion tests. The apparent chloride diffusion coefficients (CDCs) at any exposure time and erosion depth were calculated using the Boltzmann-Matano method. The influence of the type and content of SCMs, the water-binder ratio (W/B), and the type of salt solution on CICs and CDCs were investigated. Both introducing SCMs and reducing W/B effectively reduced the CIC. The SCM that most effectively reduced CIC was SF, followed by BS and then FA. Free CICs were reduced to a greater degree than total CICs in FA and BS concrete, but the opposite was true for SF concrete. Presence of calcium chloride in salt solution increased total CICs while reducing free CICs. Apparent free CDC dropped over exposure time and initially increased with erosion depth but eventually stabilized. A model of apparent free CDC considering the time-depth dependence was created, which shows that time reduction factors of CDC is larger in SCM-containing SCC than in control SCC.","PeriodicalId":18113,"journal":{"name":"Magazine of Concrete Research","volume":"38 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138576822","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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