再生碎石混凝土力学性能试验研究

Experimental Investigation on Mechanical Properties of Recycled Gravel Aggregate Concrete

针对再生粗骨料为碎石的再生混凝土,设计了99个试件,分别进行立方体抗压强度、棱柱体抗压强度、抗折强度、弹性模量和泊松比等力学性能的试验。本文研究了再生混凝土的强度指标、变形性能、损伤过程、能量耗散等特征,分析了骨料取代率对其各性能指标的影响;基于试验数据,得出各强度性能指标的换算关系;分别采用分段式本构关系模型和损伤本构关系模型对再生混凝土的应力-应变本构关系进行研究,并提出相应的本构方程。研究结果表明:与天然骨料混凝土相比,再生混凝土的各项强度指标均略为增大,但变形性能和耗能性能降低,应力-应变全曲线下降段更为陡峭;随着取代率的增大,弹性模量呈先减小后增大的变化趋势,泊松比无明显变化,与天然混凝土接近;其损伤发展过程加快,应变在ε=(3~5)×10-3时最为迅速。分段式本构方程和损伤本构方程的计算结果与试验值均能较好地吻合。

99 test specimens were designed for recycled concret which takes gravel as recycled coarse aggregate, its mechanical properties, such as cube compressive strength, prism compressive strength, flexural strength, modulus of elastisity and Poisson＇s ratio etc were tested respectively. The strength index, deformation performance, damaged process and energy dissipation etc of recycled aggregate concrete were studied; the influence of recycled aggregate replacement rate on every property index of recycled aggregate concrete was analyzed. Based on experimental data, the conversion relations of every strength index was proposed. The stress-strain constitutive relation of recycled aggregate concrete was studied by using sectional constitutive model and damage constitutive model, respectively, and the sectional constitutive equations and dama^le constitutive equations were established respectively. Experimental results show that comparing with natural aggregate concrete, every strength index of recycled aggregate concrete slightly increases, while deformation performance and energy consumption performance decline, the stress-strain curve is steeper than thhat of natural aggregate concrete in decline segment. With the increase of replacement rate, modulus of elasticity decreases first then increases; Poisson＇s ratio closes to that of natural aggregate concrete and changes insignificantly; the damaged process is accelerated, especially reaches the fastest value when ε=（3～5）×10^-3. Calculation results from both sectional constitutive equations and damaged constitutive equations are in good agreement with the experimental data.