Durability evaluation of self-compacting concrete with recycled aggregates from the precast industry

Abstract

This paper describes an experimental campaign developed with the aim of evaluating the influence of the incorporation of fine and coarse recycled aggregates (FRA and CRA, respectively) on the durability properties of self-compacting concrete (SCC). The main objective is to provide the precast industry with an alternative way of disposal and recovery of self-generated waste, minimising the consumption of natural resources and, consequently, significantly reducing the environmental impact associated with the manufacture of concrete. For this purpose, two families of concrete were produced, distinct in terms of the compressive strength of the source concrete of the recycled aggregates (45 MPa and 65 MPa), with FRA/CRA incorporation ratios of 0/0%, 25/25%, 50/50%, 0/100% and 100/0%. To evaluate the durability of the concretes, tests for water absorption, capillary absorption, oxygen permeability, electrical resistivity, chloride penetration and carbonation resistance were performed in the hardened state. The results revealed that the concrete mixes with recycled aggregate incorporated showed worse performance than the reference mixes. However, taking all the studied properties into account, it is possible to conclude that recycled aggregates from the precast concrete industry are of very good quality and can be incorporated in the production of SCC with ratios of 25/25% and 0/100% as recommended limits.