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 ρ_s, content of PVA fiber ρ_f, span-thickness ratio l/h and replacement ratio of recycled coarse aggregate (RCA) γ 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 ρ_f or ρ_s increases while they increase as γ or l/h increases. Considering the impact of ρ_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.