Bond strength and prediction model for deformed bar embedded in hybrid fiber reinforced recycled aggregate concrete

摘要

In this study, a total of 69 bond specimens were tested to investigate the bond behavior of deformed bar embedded in steel-polypropylene hybrid fiber reinforced recycled aggregate concrete (HFRAC). The test variables included steel reinforcement diameter (d = 16 mm, 20 mm, 25 mm), anchoring length (l(a) = 48 mm, 80 mm, 112 mm), steel fiber volume fraction (V-sf = 0.0%, 0.5%, 1.0%, 1.5%), polypropylene fiber volume fraction (V-pf = 0.0%, 0.05%, 0.10%, 0.15%) and recycled coarse aggregate (RCA) replacement ratio (r(g) = 0%, 30%, 50%, 70%, 100%). The results demonstrated that steel-polypropylene hybrid fibers can collaboratively improve the bond strength between steel reinforcement and HFRAC and effectively inhibit the development of micro and macro cracks, resulting in the bond specimens fail in the ductile way. The normalized bond strength linearly increased as the volume fraction of steel fiber and polypropylene fiber increased while decreased as the RCA replacement ratio increased. Furthermore, an empirical model for predicting the bond strength between deformed bar and HFRAC was proposed, which taken the effects of steel-polypropylene fibers and RCA into account. The verification against with the test results demonstrated that the proposed model is applicable to predict the bond strength of steel reinforcement embedded in HFRAC. (C) 2020 Elsevier Ltd. All rights reserved.