Durability of mortars made with sand washing waste

The industrial waste emanating from sand washing, rich in kaolinite, was used as a pozzolanic material. The durability of mortars containing 0%, 10% and 30% of calcined waste was carried out in water, in HCl and Na2SO4 solutions. In the HCl solution, the decalcification of CSH and the dissolution of portlandite were observed. Sulfates react with portlandite to produce gypsum and expansive ettringite. The durability of mortars evaluated by weight loss, expansion test, compressive strength and XRD, showed that mortars containing 10% of waste develop the highest durability in both solutions thanks to the consumption of portlandite by the pozzolan.