骨料性能对再生混凝土拉伸本构关系的影响

骨料、界面与砂浆性能是影响混凝土拉伸本构关系的主要因素，再生粗骨料表面粘附着一层老砂浆使其性能有别于天然骨料。基于随机骨料模型建立再生粗骨料混凝土五相细观数值模型，文章在验证模型可靠性的基础上研究分析再生骨料粘附砂浆的力学性能及其厚度对再生混凝土拉伸本构关系的影响规律及其作用机理，建立再生骨料混凝土拉伸本构关系。结果表明，单轴拉伸荷载作用下再生混凝土的损伤始于界面过渡区；当老砂浆厚度较小或老砂浆强度大于新砂浆强度时，再生粗骨料粘附老砂浆对再生混凝土的拉伸性能影响较小；再生混凝土的拉伸峰值应力、弹性模量和峰值变形模量随老砂浆强度增大和厚度的减小而增大，拉伸峰值应变随老砂浆强度和厚度的增大而增大。

Effect of recycled coarse aggregate properties on tensile constitutive relation of concrete

Properties of coarse aggregate, interface and mortar are main factors in the tensile constitutive relation of concrete. The surface of recycled coarse aggregate is usually covered by an old mortar layer, making it much different in properties from natural aggregate. The paper describes a five phase meso-scale numerical model of recycled coarse aggregate concrete (RCAC) that is based on the random aggregate model, and verifies its reliability using our test results. For this concrete, we also examine the trend in damage development and the effect of strength and thickness of the old mortar layer on its tensile properties, and construct its tensile constitutive relation based on our analytical results. The results show that the tensile damage to RCAC under uniaxial tension loads starts at the transition zone on an aggregate-mortar interface and then expands to the old and new mortar layers until cutting through the section of structure. When the old mortar layer is thin or its strength is greater than that of new mortar, RCAC has little change in tensile properties as the thickness or strength of old mortar layer is varied. Otherwise, its tensile stress, elastic modulus, and peak deformation modulus are all increased with an increase in the strength or a decrease in the thickness of old mortar layer. And the peak tensile strain of RCAC increase proportionally with the strength and thickness of old mortar layer.