Comparing the pozzolanic activity of aerial lime mortars made with metakaolin and fluid catalytic cracking catalyst residue: A petrographic and physical-mechanical study

We investigated the viability of a fluid catalytic cracking catalyst residue (FC3R) as an alternative sustainable pozzolanic additive in aerial lime mortars. The pozzolanic activity of FC3R was compared to that of metakaolin (MK) by chemical-mineralogical, petrographic and physical investigations. The FC3R showed lower pozzolanic activity than MK when added to aerial lime mortars, owed to the size of FC3R particles that generate less hydrated phases and give place to lower mechanical resistances in mortars. We also demonstrated that FC3R is not a compatible material for use in repair mortars, due to the formation of the harmful soluble salt ettringite.