Spent Fluid Catalytic Cracking Catalyst for Improving Early Strength of Portland Cement

Spent fluid catalytic cracking (FCC) catalyst from the petrol industry has proven to be a very active pozzolanic material. This behavior lead to an additional increase in the strength of the mortar that contains this catalyst. Pozzolanic effects tend to be considered for periods above three days, whereas in shorter times, the influence of pozzolan is usually negligible. The reactivity of FCC is so high, however, that both pozzolanic effects and acceleration of cement hydration are evident in short curing times. This paper presents a study of the effect of the presence of FCC on cement hydration and the reaction products in the first 48 hours of curing time, carried out by determining flexural and compressive strength of mortars in three different tests (substitution, addition, and with accelerator). For the FCC behavior comparison, limestone, mullite, and andalusite were used. Finally, the characterization of hydrates was performed by thermogravimetry.