Compressive strength for each of the 13 mixes was measured at four different ages: 3, 7,
28 and 90 days. At all the ages, compressive strength of control mix, CM containing
100% OPC was found to have higher strength than the rest of the mixes. There was not
much reduction in compressive strength observed for concrete mixes containing 0.15%
dosage used engine oil with respect to the corresponding control mix, i.e. CM, 40FA and
50FA. At the age of 28 days, the compressive strength of control mix, CM obtained as 42
N/mm2 and for concrete mix OPC/UEO it was 39 N/mm2. Similarly for 40FA, it was
measured as 33 N/mm2 and for 40FA/UEO it was 31 N/mm2. Compressive strength of all
concrete mixes at different ages is plotted in Figure-4