再生混凝土三轴受压力学性能试验及其影响因素

Experimental research on mechanical behavior and influence factor of recycled coarse aggregate concretes under tri-axial compression

以再生粗骨料取代率、侧向围压值、龄期、再生骨料来源和混凝土强度等级为变化参数,共设计了68个试件,通过静力三轴受压试验,获取了其在三轴受压下的应力-应变全过程曲线,揭示了再生混凝土的破坏机理和各变化参数对再生混凝土三轴受压力学性能的影响。研究结果表明:侧向围压值对再生混凝土的破坏形态有较大的影响,随着围压值的增大,破坏形态由垂直劈裂转变为斜向劈裂破坏,且与斜向劈裂面相交的粗骨料被剪断,围压值较大的试件,其峰值应力、峰值应变、初始弹性模量、变形能力等各项力学指标均有显著提高;取代率的变化对再生混凝土三轴受压的峰值应力影响不大,但对峰值应变和弹性模量的影响则较大;龄期对峰值应变和初始弹性模量有较大影响;不同服役龄期再生骨料来源对再生混凝土三轴受压力学性能影响不大;提高混凝土强度等级能有效提高再生混凝土三轴受压的各项力学性能指标。

In order to reveal the mechanical behavior of recycled coarse aggregate concrete under tri-axial compression,68 specimens were tested under tri-axial loading. Influences of some parameters,such as replacement ratio of recycled coarse aggregate,lateral confinement,age of concrete,recycled coarse aggregate sources and concrete strength,on the tri-axial compressive properties of the specimens were investigated. The failure mechanism of the specimens was revealed,the stress-strain curves of the specimens were observed,and the effect of all the changing parameters on triaxial compression mechanical performances was analyzed. The experimental results show that the lateral confinement value has a significant effect on the failure pattern of the recycled concrete under tri-axial compression; with the increase of lateral confinement value,the failure pattern charges from vertical fracture to oblique fracture,and the coarse aggregate that intersects with oblique fracture surface are cut off; increasing lateral confinement value can effectively improve the mechanical index of recycled concrete such as the peak stress,peak strain,initial elastic modulus,and deformation performance; the replacement ratio of recycled aggregate concrete has little influence on the peak stress,but has great influence on peak strain and initial elastic modulus; the age of concrete has a great influence on the peak strain and elastic modulus; different service age of recycled coarse aggregate concretes has little effect on the mechanical behaviors of recycled concrete subject to tri-axial compression; improving the strength grade of concrete can effectively enhance the mechanics performance indicators of the recycled concrete under tri-axial compression.