Cohesion coefficient of structural concrete made with recycled concrete coarse aggregate

Abstract

The cohesion coefficient of structural concrete made with recycled concrete coarse aggregate (RCA) was evaluated independently for the first time, through push-off tests having no clamping force across the shear plane, and compared with the cohesion coefficient of structural concrete made with natural coarse aggregate (NCA). Both conventionally compacted and self-compacting concretes were made with RCA and NCA as coarse aggregates. To achieve the best structural quality, concretes made with RCA were proportioned based on the equivalent mortar volume (EMV) principle instead of percentage replacement of NCA with RCA commonly followed in most of the earlier studies. Twelve transversely unreinforced push-off specimens, three from each of the four varieties of concrete, were tested to failure. Cohesion coefficients determined from analytical and finite-element modelling of the push-off tests were found to be in close conformity with each other, and the experimentally found cohesion coefficients were reasonably close to, though not in exact conformity with, the theoretical values. Nevertheless, the experimental results clearly established that RCA concrete when proportioned by the EMV method is not inferior to NCA concrete in terms of cohesion contribution to shear strength.

Editorial

“…Concrete, that mainstay of the construction industry can last a lifetime; but at the end of the concrete structure's life, can that concrete be made into new building materials rather than just hardcore? This issue's research article by Sahoo and Mathew (2020) on the use of recycled concrete as aggregate in structural concrete demonstrates that it can be a valid substitute for virgin aggregates while maintaining product quality. With this approach, less virgin aggregate needs to be extracted and the end-of-life CDE generation is reduced, giving a double benefit to the calculation: reuse of waste now and less waste in the future.…”