Effects of brick-concrete aggregates on the mechanical properties of basalt fiber reinforced recycled waste concrete

Abstract

Experimental and theoretical investigations were carried out to evaluate the effects of incorporating basalt fiber (BF) on the mechanical properties and microstructure of recycled brick-concrete aggregate concrete (RBAC). The effect of BF content (0, 1, 2, 3, and 4 kg/m³) and recycled brick aggregate (RBA) replacement ratio (0, 20, 40, 60, 80, and 100 %) on the mechanical properties of RBAC were investigated. And the failure mode, compressive strength, elastic modulus, the complete stress-strain curve, and compressive damage constitutive relation were studied. The results show that the failure mode of RBAC can be enhanced by adding BF. And the addition of BF leads to an increase in concrete compressive strength at a given RBA replacement ratio. In addition, a reduction was observed in the elastic modulus and compressive strength with an increase in the RBA replacement ratio. However, the highest compressive strength was found in the concrete with 40 % RBA replacement and a BF content of 2 kg/m3. Furthermore, an indirect model for the damage constitutive is developed to evaluate the compressive strength of BF-reinforced RBAC, which was based on the Lemaitre strain equivalence by combining the influence of BF content and RBA replacement ratio on the stress, strain, and damage coefficient of concrete. Through the observation of recycled aggregate and BF in RBAC by TM3000 electron microscope, the microscopic characteristics of recycled aggregate and the distribution characteristics and mechanism of BF in concrete are found. Therefore, the BF-reinforced RBAC can be used in construction to reduce the environmental hazards from collapsed buildings during urban renewal or earthquakes with brick and concrete waste.