Abstract :
In the present paper, an investigation is made to study the effect of maximum size of
aggregate in higher grade concrete using high volume fly ash. Three different mixes of M50
grade concrete were designed using graded coarse aggregate of three maximum sizes of
10mm, 12.5mm and 20mm. And for each mix, cement was replaced with fly ash at 0%,
10%, 20%, 30%, 40% and 50% (%replacements). All the mixes were cured for 56 days and
tested for compressive strength, flexural strength and splitting tensile strength. The test
results obtained have suggested that the maximum size of coarse aggregate in M50 grade
concrete at various replacement levels of fly ash was 12.5 mm aggregate and optimum
replacement of fly ash was 30%. The percentage increase was 20% for compressive
strength, 20% for splitting tensile strength and 5% for flexural strength when compared to
the design strength.
