Influence of interface transition zones (ITZ) and pore structure on the compressive strength of recycled aggregate concrete

IF 7.4 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY
Chenggong Lu , Qijun Yu , Jiangxiong Wei , Yanfei Niu , Yafang Zhang , Chun Lin , Peixin Chen , Chuan Shi , Pengfei Yang
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Abstract

This study aims to clarify the influence of interfacial transition zones (ITZs) and pore structure on the compressive strength of the recycled aggregate concrete (RAC). The compressive strength of the RAC are evaluated with the change of five different replacement ratios (10 %, 20 %, 30 %, 40 % and 50 %) and four various of particle sizes (5–10 mm, 10–16 mm, 16–20 mm and 20–25 mm) of the recycled coarse aggregate (RCA), the evolution process of crack propagation behavior have been accurately characterized, and the ITZs and pore structure of the RAC are analyzed. The results showed that the RAC incorporated 30 % RCA with particle size of 10–16 mm exhibited the maximum compressive strength, crack area and fractal dimension. There is a new interfacial transition zone (ITZ2) with an average elastic modulus and microhardness of about 15 GPa and 1 GPa respectively between RCA and new matrix, which deteriorates the homogeneity inside RAC; As the particle size of recycled aggregate increases, the width of ITZ2 first increases and then decreases. When the particle size of aggregate is 10–16 mm, the width of ITZ2 reaches the maximum of 50μm. Compared with ITZ2, the old interfacial transition zones (recycled aggregate-bonded mortar, ITZ3, new mortar-bonded mortar, ITZ4) have weaker mechanical properties, larger widths, and more obvious interface effects. Under uniaxial compression load, the old ITZs (ITZ3 and ITZ4) are an important factor affecting the performance and crack development of RAC. Taking the harmful pore structure of adhered mortar phase, new mortar phase, and ITZs phase as independent variables and the compressive strength of RAC as the dependent variable, a multiple linear regression model is established; through the analysis of the regression model, it is found that the ITZs are the main factor affecting the compressive strength of RAC.
界面过渡区和孔隙结构对再生骨料混凝土抗压强度的影响
本研究旨在阐明界面过渡区(ITZs)和孔隙结构对再生骨料混凝土(RAC)抗压强度的影响。RAC的抗压强度评估五个不同置换率的变化(10 % 20 % 30 %,40 50  %和%)和四个不同的粒子大小(5 - 10 毫米,10到16 毫米,16 - 20 20 - 25毫米, 毫米)的再生粗骨料(RCA),裂纹扩展行为的演化过程准确的特点,和ITZs RAC的孔隙结构进行了分析。结果表明:掺量为30 % RCA、粒径为10 ~ 16 mm的RAC抗压强度、裂纹面积和分形维数最大;RCA与新基体之间形成了一个新的界面过渡区(ITZ2),平均弹性模量和显微硬度分别约为15 GPa和1 GPa,使RAC内部的均匀性恶化;随着再生骨料粒径的增大,ITZ2的宽度先增大后减小。当骨料粒径为10 ~ 16 mm时,ITZ2的宽度最大达到50μm。与ITZ2相比,旧的界面过渡区(再生骨料粘结砂浆、ITZ3、新砂浆粘结砂浆、ITZ4)力学性能更弱,宽度更大,界面效应更明显。在单轴压缩荷载作用下,旧ITZ3和ITZ4是影响RAC性能和裂纹发展的重要因素。以粘结砂浆相、新砂浆相和ITZs相的有害孔隙结构为自变量,RAC抗压强度为因变量,建立多元线性回归模型;通过对回归模型的分析,发现ITZs是影响RAC抗压强度的主要因素。
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来源期刊
Construction and Building Materials
Construction and Building Materials 工程技术-材料科学:综合
CiteScore
13.80
自引率
21.60%
发文量
3632
审稿时长
82 days
期刊介绍: Construction and Building Materials offers an international platform for sharing innovative and original research and development in the realm of construction and building materials, along with their practical applications in new projects and repair practices. The journal publishes a diverse array of pioneering research and application papers, detailing laboratory investigations and, to a limited extent, numerical analyses or reports on full-scale projects. Multi-part papers are discouraged. Additionally, Construction and Building Materials features comprehensive case studies and insightful review articles that contribute to new insights in the field. Our focus is on papers related to construction materials, excluding those on structural engineering, geotechnics, and unbound highway layers. Covered materials and technologies encompass cement, concrete reinforcement, bricks and mortars, additives, corrosion technology, ceramics, timber, steel, polymers, glass fibers, recycled materials, bamboo, rammed earth, non-conventional building materials, bituminous materials, and applications in railway materials.
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