The aim of this research is to study the effect of (Used Engine Oil) (UEO) on the properties of fresh and hardened concrete and its effect on the properties of the hardened concrete under high temperature, the (UEO) used as a plasticizer material, adding an air-entrained to the fresh concrete, thus improving workability of the fresh concrete. The (UEO) is used as percentage of cement weight (0.1,0.15, 0.2%) ,the 28 day concrete is exposed to different levels of high temperature (200,400,600°C) for 1.0 hr, the concrete samples were tested after
24 hr of cooling, two methods were used to add the (UEO), First Method: adding the (UEO) during the mixing process (mixing the dry materials and water after that the used engine oil was added), The Second Method: An emulsion mixture consisting of oil and water was prepared for the different percentages of additions this emulsion was used after mixing the dry materials, the mixing time was 4 minutes. Results showed that the effect of using the (UEO) is similar to that of air-entraining chemical to fresh concrete, its effect appears on the (initial & final setting time, slump and air content) and also affects the properties of hardened concrete.
Keyword: used engine oil, concrete, high temperature, air-entrained.