Oil sludge as a fuel and raw material in the production of cement-based pozzolanic composites

The aim of this study was the valorisation of oil sludge as an alternative fuel in the cement kilns since 1 kg of oil sludge can substitute 0.82 m3 of methane. The ash from oil sludge combustion can be used as secondary cementitious material, for the production of cement-based pozzolanic composites. The elemental composition, density, surface properties, and particle size distribution of the ashes were measured. Then the ashes were used along with ordinary Portland cement at different ratios of substitution: 5, 10, 15, and 20% by mass to produce mortars which were tested for their normal consistency, setting time, mechanical properties, and then compared to reference mortar without ashes. According to the results, the higher SiO2 content was assigned to ash compared to cement. The incorporation of ash resulted in the retardation of the setting. According to European standard EN-197, the mortar with the addition of 5% of ash which presents a maximum strength equal to 46 MPa obtained at 28 days is classifi ed as CEM II/B 42.5N. However, cements containing 10% and 20% of ash have been classifi ed in strength class 32.5N