Sprayed Concrete with Recycled Aggregates for Swimming Pools Structures

Abstract

Construction and demolition wastes (C&DW) are often deposited in landfills and dumpsters in urban perimeters, causing weighty environmental and social impacts. The reuse of C&DW in innovative concrete formulations is a good solution for both problems. Recycled aggregates (RA), prepared from C&DW, generally show lower quality properties than natural aggregates. This reuse has been extensively studied mainly in conventional concrete, although there are few studies regarding the incorporation of RA into the sprayed concrete and the information is almost non-existent. The use of sprayed concrete is a flexible, economical and fast construction method, but it requires specialized skilled workers and a high degree of mechanization. It is fairly common to use this technique in new construction structures such as vaults, tunnels, canals, reservoirs, swimming pools and sewers. In Algarve, sprayed concrete is used in the construction of more than 70% of all swimming pools. Under the project SPOOLs-sustainable pools, whose objective is to develop more sustainable pools, it was developed a composition of sprayed concrete that incorporates RA. This paper presents the results of strength and durability from several mixtures of hardened concrete and the prescription of the optimized composition, regarding the existing regulations. At the same time, there were also assessed the consequences upon the quality of the sprayed concrete when the operator, through the dry projection method, adds different amounts of water. Significant environmental savings would be gained if part of the required materials for this production, would be replaced by recycled material, such as RA.