تأثير إضافة غبار السليكا والرماد المتطاير وزيت المحركات المستعمل على الخواص اللدنة والمتصلبة للخرسانة ذاتية الدمك

This study aims to investigate the varying effects of used car engine oil, silica fume, and fly ash on the fresh and hardened properties of self-compacting concrete. A reference mix without the mentioned additives was used for comparison. Three mixes were prepared with used Car engine oil added at rates of (0.5, 1, and 1.5)%, while silica fume was incorporated into three mixes at (6, 10, and 12)%. Finally, fly ash was added to two mixes at (25 and 30) %. The results of self-compacting concrete in its fresh state showed that the mix containing 6% silica fume achieved the largest flow diameter of 805 mm. Meanwhile, the lowest slope in the L-box test (which indicates better performance) was recorded for the concrete mix containing 30% fly ash, with a slope value of 0.920. An improvement in viscosity and a reduction in bleeding water were observed in the mixes containing additives compared to the reference mix. As for the results of self-compacting concrete in its hardened state, the best compressive strength at curing periods of 7 and 28 days was achieved by the reference mix. Meanwhile, the highest value in the indirect tensile strength test was recorded for the mix containing 25% fly ash. Keywords: silica fume, fly ash, used Car engine oil, self-compacting concrete