Physical and mechanical behavior of concrete specimens using recycled aggregate coated using recycled cement paste

Abstract

Various countries have implemented the use of recycled concrete aggregates (RCA) as an alternative to reduce the use of natural resources. The replacement of RCA for natural aggregates (NA) in concretes is limited to small percentages because of the quality of the old mortar which is still adhered to the RCA. This mortar is more porous and absorbent, weakening the RCA and causing losses in the physical and mechanical properties of new concretes. In addition, the smaller the particles, the greater the amount of adhered mortar, which is why its use in concrete is limited and the fine fraction tends to be discarded. In this study, the use of RCA coated with recycled binder paste (RBP) (smaller than 45 μm) from the crushing of the RCA itself is sought to strengthen weak adhered mortar and improve the properties of the RCA through an economic and sustainable treatment by using the waste of the waste. Therefore, the mechanical, physical and chemical behavior and durability of the concretes are assessed by the use of RCA coated with RBP (replacing by 0%, 50% and 100%). The results indicate a reduction in the mechanical and physical properties of the concrete for the highest replacement percentage of RCA. Nevertheless, the coated recycled aggregate concrete (RAC) showed superior behavior to the untreated RAC, obtaining compressive strengths close to the control and a remarkable improvement in the physical assays.