STUDIES ON RCA CONCRETE

Abstract

A comparison with the ACI 318-08 based prediction of the efficiency factors of unreinforced bottle-shaped struts made of RCA concrete is presented. Such struts play an important role in the internal load transfer mechanisms of deep beams, grade beams, corbels and pile caps etc. The objective of this experimental study was to ascertain whether strut-efficiency factors in current design codes originally meant for natural coarse aggregate concrete can be conservatively applied to RCA concrete or not. The results of the comparison indicate that the ACI 318-08 gave conservatie predictions for the efficiency factors of unreinforced RCA bottle-shaped struts; rather even the efficiency factors for reinforced bottle-shaped struts specified in the ACI, the AASHTO as well as the Eurocode were conservative with respect to the values measured in this investigation. It is desirable that recommendations for strut-and-tie modelling of structural concrete should be included in the Indian concrete design code, IS 456:2000.