Improvement of the durability of concrete with recycled aggregates in chloride exposed environment

Abstract

Recycled aggregates concrete (RAC) becomes an important participant in recycled materials although there are still questionable properties of it, like chloride penetration and diffusion. An extensive experimental campaign was performed in order to evaluate the effect of recycled concrete aggregates (RCA) over some properties of concretes. Composition and mix design influence on the concrete were studied in mixes ranging from 0.45 to 0.60 w/c ratios, with 0%, 20%, 50% and 100% coarse aggregates replacement. Concretes were submitted to saline attack and the total chloride contents were determined as well as the chloride penetration profiles. Both new cement paste and RCA from different concrete mixes were analysed by XRD and SEM in order to evaluate the chlorides binding. A chloride binding phenomenon is detected in RAC which may compensate the RCA higher permeability. According to chloride diffusion results, high RCA content lead to an improvement of durability in RAC with sufficiently low w/c ratio, in terms of chlorides presence.