Compatibility of fluid catalytic cracking catalyst residue (FC3R) with various types of cement

Zeolitic catalysts are widely used in petrochemical refining. When the catalytic properties of this product are degraded, the deactivated catalyst must be replaced. Its chemical composition, based in silicoaluminates, together with its zeolitic structure, can be used in concrete, due to its high pozzolanic activity. Mortars were prepared using faujasite-based spent catalyst as a cement replacement (in quantities up to 15%). The mechanical properties (compressive and flexural strengths, and porosity) of these mortars were tested using several water/binder (w/b) ratios (0.4–0.6), curing times (7–90 days) and cement types (CEM I 52.5 R, CEM I 42.5 R, CEM II 42.5 R B-M (V-LL) and CEM II 32.5 N). Thermogravimetric analyses of the pastes were also performed. High short-term pozzolanic activity of the zeolite FC3R and high strength gains were observed in the substituted mortars. During the testing period no negative effects in the mechanical properties were observed for the range of substitutions used. It was found that when the w/b ratio is low, a plasticiser must be used because FC3R has a high water demand. This effect can be partially compensated by using fly ash in the mix, because the spherical shape of fly ash enhances the workability of the mortars.