EFFECT OF MAXIMUM PARTICLE SIZE OF COARSE AGGREGATES ON THE COMPRESSIVE STRENGTH OF NORMAL CONCRETE Nura Hassan and Ahmed Mohammed B. Department of Civil Engineering Technology, Federal Polytechnic Damaturu E-mail: nura2108@yahoo.co.uk

ABSTRACT: This research work presents the investigation on the effect of maximum size of aggregates on the compressive strength of concrete.  Nominal mix ratios of 1: :3, 1:2:4 and 1:3:6 were prepared using two different water/cement ratios, that is 0.5 and 0.6. Five different sizes of coarse aggregates, that is, 5mm, 12mm, 20mm, 25mm, and 38mm were used. The concrete cubes cast were cured for the period of 14 and 28 days before testing for compressive strength. The research revealed that water absorption of the coarse aggregates increases with the decrease in aggregate size, consequently, the water demand in the concrete mix. It was also found that of the coarse aggregates, size 20mm produced concrete with highest compressive strength in all the mixes irrespective of water/cement ratio and curing age. Concrete’s compressive strength increases with increase in curing age and with richer mixes. Based on the findings of the research, it was concluded that 20mm aggregate is the most suitable for the production of normal strength concrete.