OPTIMIZATION OF USED ENGINE OIL AS ADMIXTURE IN CONCRETE USING RESPONSE SURFACE METHODOLOGY

Maintenance of industrial machinery and automobile engines produces a large amount of Used Engine Oil (UEO) as waste. This waste oil is harmful to the environment, pollutes the land and kills the aquatic habitats. Used engine oil poured into household drains or directly onto the field will pollute fresh water by entering rivers and groundwater. Efforts are shifted to conversion of Used Engine Oil into useful material for concrete production as a replacement for SP430 superplasticizer. This research deals with optimizing Used Engine Oil in M20 grade concrete using response surface methodology. The oxide composition of UEO revealed 37% of SO3, 15.5% of CaO, 17.7% OF ZnO, 9% of P2O5. The research revealed that the workability of the concrete mixes were between medium and high. The control mix slump value was 50mm but when UEO and superplasticizer were used, the slump obtained were 54mm and 52mm respectively. Concrete samples were produced and strength properties were tested at 7, 14 and 28 days of curing by water immersion. The test result showed that water absorption decreased with increase in UEO. Compressive strength increased with increase in dosage and curing days. Also, there was gradual increase in flexural and splitting tensile tests with the increase in UEO. Model equations and optimal values of UEO concrete were generated by numerical optimization. The optimal value was 11.4ml of UEO at 28 days which gave compressive strength result of 26.7 N/mm2 , flexural strength 8.3N/mm2 , tensile strength 18.9 N/mm2 and water absorption of 0.7%. Therefore, 11.4ml of UEO is recommended for use as superplasticizer in M20 grade concrete.