Synthesis and hydration of ye'elimite-containing cement (YCC) produced with spent fluid catalytic cracking catalyst

The consumption of petroleum products from fluidized bed catalytic cracking (FCC) units has increased worldwide. One of the primary materials used in this process is the zeolitic catalyst which loses its catalytic capacity over time, generating the spent FCC catalyst - SFCC. This work evaluated the feasibility of using SFCC as raw material for ye'elimite-containing cements (YCC) production. Specifically, six types of clinkers were syn-thesized in the laboratory, varying the ye'elimite content, with and without SFCC. Powder and in-situ X-ray diffraction (XRD), isothermal calorimetry, and thermogravimetric analysis (TGA) were conducted in anhydrous and hydrated samples. Clinkers with SFCC stabilized more C4AF than those without SFCC; so there was less Fe3+ available in these systems than in the reference systems to stable the pseudo cubic ye'emelite. As a result, the SFCC-containing cements (with more orthorhombic ye'elimite) had higher reaction rates within the first 12-20 h of hydration. In turn, the higher ye'elimite contents in the high-and medium-ye'elimite reference clinkers led to the further formation of hydrated phases at 28 days of hydration on these samples. The equivalent ye'elimite content in low-ye'elimite clinkers led to equivalent cumulative heat and phase assemblage from 48 h to 28 days. Overall, the use of SFCC allowed to incorporate of up to 20.81 wt% of the residue in raw material replacement, resulting in cements with increased early-age reactivity.