Analysis of cement mortar performance enhanced by fluid petroleum catalyst residue (FPCR)

Abstract Portland cement production is a major contributor to global CO₂ emissions and natural resource depletion, highlighting the need for sustainable supplementary cementitious materials. Fluid Petroleum Catalyst Residue (FPCR), a by-product of petroleum refining, poses significant disposal challenges but contains reactive aluminosilicate phases with potential for partial cement replacement. This study aims to evaluate FPCR’s technical feasibility in mortar production, determine its optimal dosage, and assess its impact on key fresh and hardened properties. Mortar mixes were prepared with 0%, 10%, 20%, 30%, 40%, and 50% FPCR replacing ordinary Portland cement by mass at a constant water-to-binder ratio of 0.40. Tests included setting time, compressive and flexural strength (3–56 days), water absorption (28 days), and scanning electron microscopy (SEM) microstructural analysis to identify hydration products and pore structure changes. Results showed a slight but practically insignificant reduction in initial setting time (≤ 4 min) with FPCR addition. Compressive strength increased by up to 12% at 28 days for 10% FPCR but decreased by up to 25% at 56 days for ≥ 30% replacement levels. Water absorption was reduced by 10–15% for 10–20% FPCR, while higher dosages increased porosity. SEM observations revealed secondary hydration products including calcium silicate hydrate (C–S–H) gel, calcium hydroxide, and ettringite, forming a dense matrix around FPCR particles at low replacement levels. Based on these findings, 10% FPCR is recommended as the optimal level for general mortar applications, with 20% suitable in non-structural, sustainability-driven contexts. Future research should include larger datasets for statistical validation, extended curing ages, comparative studies with other pozzolans, and full durability and life-cycle assessments to support practical implementation.