Influence of Accelerators on Cement Mortars Using Fluid Catalytic Cracking Catalyst Residue (FCC): Enhanced Mechanical Properties at Early Curing Ages

Abstract

Supplementary cementitious materials (SCMs) have been used in the construction industry to mainly reduce the greenhouse gas emissions associated with Portland cement. Of SCMs, the petrochemical industry waste known as fluid catalytic cracking catalyst residue (FCC) is recognized for its high reactivity. Nevertheless, the binders produced using SCMs usually present low mechanical strength at early curing ages. This study aims to assess the effect of different accelerating additives (KOH, sodium silicate SIL, commercial additive SKR) on the mechanical strength of mortars containing FCC. The results show that after only 8 curing hours, the compressive strength gain of the FCC mortars containing SKR was over 100% compared to the FCC mortar with no additive (26.0 vs. 12.8 MPa). Comparing the compressive strength of FCC mortar containing SKR to the control mortar, the enhancement is spetacular (6.85 vs. 26.03 MPa). The effectiveness of the tested accelerators at 8–24 curing hours was KOH ≈ SIL < SKR, whereas it was KOH < SIL < SKR for 48 h–28 days. The thermogravimetric data confirmed the good compatibility of FCC and the commercial accelerator.