Strength, durability and leaching behaviour of mortar containing spent catalyst as partial replacement for river sand

The effects of using spent catalysts (residues from petroleum refining processes) as a partial replacement for river sand in mortar mixtures were investigated in an attempt to promote sustainable construction practices. Seven mixtures were prepared, replacing river sand with spent catalyst in 5% increments up to 30%. Experiments were conducted to assess the mortars’ strength, durability and leaching behaviour at different curing periods. The flowability and bulk density of the fresh mortar decreased continuously with an increase in the percentage of spent catalyst. The compressive strength of the mortar remained similar to that of the standard mix up to 10% replacement; beyond that replacement level, the strength decreased slowly. The water absorption and total porosity of the mortar increased with a higher replacement level. The experimental results were statistically analysed by analysis of variance, which showed that all the data were statistically significant. Scanning electron microscopy analysis revealed that micropores increased continuously with an increase in the content of spent catalyst. The toxicity characteristic leaching procedure was used to determine the environmental safety of heavy metal leaching. The results indicated that the leachate of heavy metals was well below the Indian standard limits for all types of mortars.