Self-Compacting Concrete with Recycled Concrete Aggregate: Resistance against Aggressive External Agents

Abstract

The use of waste in civil-engineering products, such as concrete and asphalt mixes, is a very effective strategy for reducing high consumption levels of Natural Aggregates (NA) in the construction sector. In this research, rejected precast concrete elements of high compressive strength are studied, following their crushing for use as a high quality Recycled Concrete Aggregate (RCA) in the manufacture of Self-Compacting Concrete (SCC). High volumes of this waste stream are employed in the mixture, completely replacing the coarse fraction of the natural aggregate (100% replacement rate) and half of the fine fraction (50% replacement rate). Once hardened, samples of the recycled SCC are exposed to several aggressive external agents, in order to evaluate their performance and durability in aggressive environments. Behavioral tests on the concrete in the presence of the most frequent aggressive agents in the surrounding environment demonstrated that the SCC containing RCA was resistant to freeze/thaw and moist/dry cycles, and sulphate attack, according to the results obtained in 4, 3 and 2 samples respectively, and of sufficient durability for use in structural concrete components.