A Model for Predicting Crack Width of PVA Fiber-Reinforced Recycled Aggregate Concrete Slabs

The four-point loading tests of polyvinyl alcohol fiber-reinforced recycled aggregate concrete (PVAF-RRAC) slabs are conducted and the impacts of reinforcement ratio rho s, content of PVA fiber rho f, span-thickness ratio l/h and replacement ratio of recycled coarse aggregate (RCA) gamma on crack formation mechanism, crack spacing and crack width are analyzed. The failure modes of recycled aggregate concrete (RAC) slabs and PVAF-RRAC slabs are distinguished by yield of longitudinal tensile reinforcement and fragmentation of concrete in compression zone. Meanwhile, the damage of PVAF-RRAC slabs is also accompanied by pull-out or broken of PVA fibers along crack gaps. In contrast, the concrete crushing phenomenon of PVAF-RRAC slabs is not distinct, indicating PVA fibers incorporation could improve flexural performance. The average spacing and maximum crack width of PVAF-RRAC slabs are relatively small, the crack distribution is more uniform. The crack development rate and crack width decrease as rho f or rho s increases while they increase as gamma or l/h increases. Considering the impact of rho f on average crack spacing, a formula for approximately forecasting the average crack spacing of PVAF-RRAC slabs is proposed. Additionally, an influence coefficient of RCA is introduced, a prediction model for crack width in PVAF-RRAC slabs is established and test data are validated with favorable results.