Simulation of cracking susceptibility in recycled concrete aggregate systems

This paper presents an investigation into the cracking susceptibility of concrete made with recycled concrete aggregates through two-dimensional numerical finite element simulations. Due to the limited experimental data on the performance of Recycled concrete Aggregate Concrete (RAC) in both compression and tension, a series of finite element simulations were performed on a RAC systems with a range of adhered mortar contents for a regular 100 mm RAC cube. The finite element simulation was performed for 0%, 2%, 4%, 10%, 20%, 50%, and 100% adhered mortar contents in order to examine the compressive and tensile behavior of the RAC cube under monotonic loading. Experimental image analysis was used to map the physical geometry of each materialto the finite element model. Loading conditions were prescribed as a strain deformation for the monotonic loading, and sequential crack initiation and crack propagation were also explored. Simulated compressive strengths decreased by 11% between 0% and 50% adhered mortar contents, simulated tensile strengths remained consistent across adhered mortar contents, and modulus of elasticity degraded with adhered mortar content. Both compressive and tensile stress-strain behaviors have showed a slight increase in strain at cracking with increasing adhered mortar content, highlighting an apparent deformability in RAC systems. Stress concentrations were observed near the adhered mortar and interfacial transition zone boundaries, which emphasizes the fact that the fracture path initiates within the new interfacial transition zone.