Shear strength of reinforced recycled concrete beams without stirrups

A new method of mixture proportioning is used for investigating the shear performance of reinforced concrete (RC) beams made with coarse recycled concrete aggregate (RCA). In this method, RCA is treated as a two-phase material comprising mortar and natural aggregate therefore to proportion the concrete mixture with RCA, the relative amount and properties of each phase are considered separately. Using the new mix proportioning method, several beams were designed and tested to study the effect of a number of parameters including the shear span-to-depth ratio and beam size on the serviceability and strength of RCA concrete beams without shear reinforcement. For each beam its load–deflection curve, shear deformations, diagonal cracking load, crack pattern, ultimate shear strength and failure mode were determined. The results showed that the shear performance of RC beams made with RCA can be comparable, or even superior, to that of beams made entirely with natural aggregates at both serviceability and ultimate limit states, provided the proposed mixture proportioning method is used. Furthermore, the simplified methods of ACI and CSA standards as well as Eurocode 2 were found applicable to all reinforced RCA-concrete beams.