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为了研究再生粗骨料取代率对再生混凝土力学性能的影响,利用废弃混凝土为再生粗骨料来源,研究取代率从0%至100%变化,中间级差为10%的11种再生混凝土,制作了33个标准立方体、33个标准棱柱体和33个尺寸为150 mm×150 mm×550 mm的棱柱体再生混凝土试件,依标准试验方法进行力学性能测试。通过试验,获取了再生混凝土取代率与立方体抗压强度、轴心抗压强度、抗折强度、应变延性系数、耗能系数、割线刚度和损伤度等力学性能指标之间的关系。研究结果表明:随着再生粗骨料取代率的增加,再生混凝土立方体抗压强度和轴心抗压强度总体呈现增长的趋势;抗折强度呈现先增长后减小的趋势;弹性模量总体呈现减小的趋势;延性系数、耗能系数、割线刚度总体均呈现减小的趋势但减小幅度较小;再生混凝土的刚度退化和损伤累积过程与天然混凝土较为一致。综合考虑再生混凝土基本力学性能指标和经济性能指标,建议以30%~40%作为再生混凝土的最优取代率。
In order to study the influence of recycled coarse aggregate substitution rate on the mechanical properties of recycled concrete, 11 kinds of recycled concrete with substitution ratio ranging from 0% to 100% and intermediate difference of 10% were studied using waste concrete as the source of recycled coarse aggregate. 33 standard cubes, 33 standard prisms and 33 prismatic regenerated concrete specimens measuring 150 mm × 150 mm × 550 mm. The mechanical properties were tested according to standard test methods. Through the experiment, the relationship between the replacement ratio of recycled concrete and mechanical properties such as compressive strength, compressive strength, flexural strength, strain ductility coefficient, energy dissipation coefficient, secant stiffness and damage degree were obtained. The results show that with the increase of replacement rate of recycled coarse aggregate, the compressive strength and axial compressive strength of recycled concrete cube show an overall trend of growth; flexural strength first increases and then decreases; elastic modulus presents in general The ductility coefficient, the energy dissipation coefficient and the secant stiffness all show a decreasing trend but with a smaller decreasing extent. The stiffness degradation and damage accumulation process of recycled concrete are in good agreement with those of natural concrete. Taking into account the basic mechanical properties of recycled concrete and economic performance indicators, it is recommended to 30% ~ 40% as the optimum replacement of recycled concrete.