不同养护龄期下再生粗骨料混凝土拉伸本构关系

Tensile Constitutive Relationship of Recycled Coarse Aggregate Concrete at Different Curing Ages

采用MTS疲劳试验机进行了再生粗骨料混凝土轴向拉伸试验,研究分析再生粗骨料取代率对不同养护龄期下再生粗骨料混凝土轴向拉伸应力-应变全曲线的影响规律,并提出了再生粗骨料混凝土拉伸本构关系模型.研究结果表明:再生粗骨料混凝土轴向拉伸应力-应变全曲线的上升段斜率较普通混凝土低,下降段随着再生粗骨料取代率提高与养护龄期的增长而变陡;再生粗骨料混凝土的弹性模量随着养护龄期的增长呈线性增长,当荷载超过50%之后,其变形模量的下降速度快于普通混凝土;早龄期再生粗骨料混凝土的拉伸峰值应变随着再生粗骨料取代率的增大而增长;养护龄期低于7d时,再生粗骨料混凝土的抗拉强度增长速率快于普通混凝土;再生粗骨料混凝土的拉压比随着养护龄期的增长而下降.

Axial tensile stress-strain curve of recycled coarse aggregate concrete(RCAC)was tested on MTS fatigue test machine.Influence of replacement ratio of recycled coarse aggregate(RCA)and curing age on axial tensile stress-strain curves of RCAC were analyzed,and tensile constitutive model of RCAC was proposed.The results show that the slope of RCAC tensile stress-strain curve on the ascending stage is lower than that of ordinary concrete,and after peak stress the curve droppes steeper with the increase of the replacement ratio of RCA and curing age.Elastic modulus of RCAC is in linear growth with the curing age increasing,and when the load exceeds 50%the deformation modulus of RCAC drop further than ordinary concrete.At the early age,tensile strain at peak stress of RCAC increases with the increase of RCA replacement ratio,the tensile strength growth rate of RCAC is faster than that of ordinary concrete.The tensile-compression strength ratio of RCAC reduces with the curing age.