Effect of low dosages of waste GRP dust on fresh and hardened properties of mortars: Part 1

The viability of improving some durability aspects of mortars through the addition of low dosages of very fine Glass Reinforced Plastic by-product was investigated. Replacing 5–10% of sand volume with GRP dust delays the setting time of cement paste, but the delay can be partially recovered by adopting a previously thermally treated GRP dust. GRP dust increases the workability, autogeneous shrinkage, deformability and total porosity of mortars, though with a smaller average radius. It significantly reduces the mechanical performance of mortars when wet curing conditions are adopted. However, the risk of cracking induced by restrained shrinkage and capillary water absorption is lower in the presence of GRP dust. This decrease could imply enhanced durability of GRP mortars when used as supporting role.