Performance of recycled concretes exposed to sulphate soil for 10 years

Abstract

Recycled aggregate concretes, particularly those made with crushed concrete in replacement of the natural coarse aggregate, have been increasingly used in the last decades. Although compressive strength is not affected by the replacement of conventional coarse aggregates by recycled coarse aggregates (RCA), there is still some disagreement regarding their durable performance, particularly when they are exposed to severe conditions. This study evaluates the performance of recycled concretes made with different RCA contents (25%, 50%, 75% and 100%) exposed to sulphate soil for more than 10 years. Concretes designed with and without provisions for durability to sulphate attack were exposed. The specimens were half buried in sulphate soil and their condition was periodically assessed by visual inspection, weight loss and dynamic modulus of elasticity. Additionally, the extent of the attack on mortar-coarse aggregates interfaces was studied by stereomicroscopy and optical microscopy. Results to date indicate similar performances for recycled aggregate concretes and natural aggregate concretes with the same compressive strength level, even for a 100% RCA content.