Influence of treated recycled concrete aggregate on concrete properties

Abstract

The amount and the quality of the old cement mortar attached to the aggregates influence the quality of the recycled concrete aggregate (RCA) produced. The characteristics of RCA adversely affect the physical, mechanical and durability properties of concretes. Due to these adverse effects, it is necessary to improve the RCA properties, not only changing their surface but also their internal microstructure. The main objective of this research work was to analyse the influence of chemically treated RCA on the properties of recycled aggregate concrete (RAC). The RCA was exposed to three chemical treatments, namely; silica fume (SF), waterglass (WG) and silica nanoparticles (Nano). Once the physical properties of both the untreated and treated RCA had been determined they were then employed in concrete production. RAC were produced employing 25% and 50% of RCAs in substitution of natural coarse aggregates. The obtained results by the RAC produced employing treated RCA were compared to those of the conventional concrete as well as to those of the RAC employing untreated aggregates. According to the results, the RAC produced employing RCA treated with WG and Nano achieved better compressive strength and durability properties than the RAC or CC concrete at 28 and 90 days.