Chemical activation of pozzolanic reaction of fluid catalytic cracking catalyst residue (FC3R) in lime pastes: thermal analysis

In this paper, the role and reactivity of fluid catalytic cracking catalyst residue (FC3R) as a pozzolanic mineral admixture are studied. For that purpose, thermogravimetric (TG) studies of several FC3R/lime pastes, activated by using different chemical compounds (NaOH, gypsum, CaCl₂ and Na₂SO₄), were performed. First, lime fixation and the nature of the hydration products were characterised from TG curves. Second, sodium sulphate was considered as the best chemical activator in the lime fixation process, yielding a 100% of fixed lime for short curing periods. In addition, hydrated gehlenite crystals incorporating sulphate ions were identified, mainly in cured pastes. From these experimental studies, it can be concluded that FC3R is a very good pozzolanic material for inclusion in lime pastes and mortars, and the addition of a small amount of Na₂SO₄ and CaCl₂ enhanced the reactive ability of FC3R with hydrated lime.