Composite shear mechanical properties of carbon fiber recycled aggregate concrete

To study the mechanical properties of carbon fiber recycled aggregate concrete under composite shear condition, the composite shear test of 102 cube specimens was completed with recycled coarse aggregate replacement rate, compressive stress ratio and carbon fiber content as test parameters. The failure mode of carbon fiber reinforced recycled concrete specimens was observed, and the load-displacement curve under shear state was obtained. The effects of three kinds of change parameters on the shear strength, peak displacement, and damage evolution law of specimens were analyzed. The research shows that the compressive stress ratio has a significant indigenous effect on the failure mode of the carbon fiber reinforced recycled concrete specimen, and the number and angle of cracks increase with the increase of the compressive stress ratio. 0.3vol% content of carbon fiber can improve the shear strength of the specimen by about 12%. When the compressive stress ratio increases from 0 to 0.09 and 0.18, the shear strength of the specimen is 2.34 and 3.25 times that of the specimen, respectively. The recycled coarse aggregate replacement rate has little effect on the peak shear strength. Increasing the compression stress ratio can effectively slow down the development of damage, and the adopted damage constitutive can better reflect the shear-displacement relationship of composite shear.