Bond, tension‐stiffening, and cracking in multi‐generational recycled aggregate concrete subjected to shrinkage strains

Abstract The concrete industry is responsible for a significant portion of global waste production and multi‐generation recycled aggregate concrete (MGRAC) is a means to allow the sector to transition to a circular economy framework. To predict the behavior of MGRAC at the member level there is a need to understand the underlying mechanics of bond, tension‐stiffening, and cracking. To date, no work has been completed on tension‐stiffening of MGRAC. In this paper, the cracking and tension‐stiffening behavior is investigated for four concrete mix designs encompassing four generations of concrete which have undergone substantial shrinkage over 600 days. The results show that the compressive and tensile strength were not impacted by the use of MGRAC. Similarly, limited change was observed between bond stress/slip relationships and tension‐stiffening over each generation. Crack‐widths generally increased over concrete generations with a decrease in the overall number of tension‐stiffening cracks. The presence of surface micro‐cracks was found to increase over the generations, indicating the need for future member level durability analysis. Comparison to existing modeling approaches showed existing methods provide a reliable upper bound prediction of crack‐width.