Durability of concrete produced with recycled cement from waste concrete
José Alexandre Bogas, Ana Carriço, Sofia Real
Abstract
In the present study, concretes produced with recycled cement (RC) obtained from the thermoactivation of concrete waste (RCCW) or laboratory cement paste (RCPW) were analysed in terms of some of their main transport properties (capillary absorption, oxygen permeability) and carbonation and chloride penetration resistance. Recycled cement was incorporated at various percentages, between 5% and 100%, taking into account concretes of different w/b. RCCW was obtained from an innovative process of concrete waste separation recently patented by the authors, allowing the retrievement of cement waste with almost 90 vol% purity. RCPW and RCCW showed high rehydration capacity and concrete produced with them reached comparable durability to that of reference ordinary Portland cement (OPC) concrete. For up to 15% RCCW replacement the concrete durability was not significantly affected and the cement retrievement from concrete waste was very effective. Overall, RCPW and RCCW actively contributed to the densification of the microstructure and the improvement of concrete durability. The recycled cement, as obtained in the present study, showed high potential to be used as an eco-efficient clinker substitute.