Mechanical performance of shotcrete produced with recycled coarse aggregates from concrete

Abstract This research intends to analyse the mechanical performance of shotcrete with coarse recycled concrete aggregates (CRCA). Four replacement ratios of coarse natural aggregate with CRCA were studied: 0%, 20%, 50% and 100%. A dry mix-process was used in the production of shotcrete. A considerable reduction of the rebound effect with the incorporation of recycled aggregates was observed. In terms of hardened properties, a reduction was observed in compressive strength, splitting tensile strength, modulus of elasticity and ultrasound pulse velocity. The adhered mortar in CRCA is the reason for their greater deformability and lower strength, which were reflected in a decline of the properties of shotcrete. However, the abrasion resistance increased with the incorporation of recycled aggregates, which can be explained by its roughness and higher porosity, allowing better bond with the new cement paste. The adhesion strength in the various compositions was not affected by the incorporation of these aggregates.