This work presents the relation between the pozzolanic activity, the hydration heat and the compressive strength developed
by blended mortars containing 10 and 35% of a spent fluid catalytic cracking catalyst (FCC).
The results show that, in comparison with 100% Portland cement mortar, a mortar with 10% FCC increases the hydration heat
all over the period of testing. This hydration heat increasing is due to the pozzolanic effect, therefore the resulting compressive
strength is higher than the reference mortar. Whereas, in a mortar with 35% of FCC, the hydration heat is higher than 100%
PC mortar, until 10 h of testing. After this age, the substitution degree predominates over the pozzolanic activity, showing
in this case, lower hydration heat and developing lower compressive strength than 100% PC mortar.