Durability performance of dry-mix shotcrete produced with coarse recycled concrete aggregates

The purpose of this research is to study the effect of replacing natural coarse aggregates with coarse recycled concrete aggregates on shotcrete's durability performance. The dry-mix process was used and four mixes with 0%, 20%, 50% and 100% replacement ratios were analysed. The incorporation of recycled aggregates demanded an increase of the w/c ratio to maintain the workability in all the mixes, and resulted in reductions of the rebound effect, which is a very positive consequence since it is one of the biggest disadvantages of the dry-mix process. To characterize the durability of shotcrete, the following tests were conducted: water absorption by immersion, water absorption by capillarity, carbonation resistance, chloride ion penetration resistance and shrinkage. In all of them, a performance loss occurred. Nevertheless, all the losses were low, which means that, if considered in the design of the shotcrete, this type of aggregates can be used.