Mineral aggregates make up 90 to 96% of a HMA mix by weight or approximately 75 to 85% by
volume. The properties of the mineral aggregates have significant affects in performance of our
roadways which offers the possibility of investment in these properties towards resisting different
ranges of external applied loads and environmental conditions. Therefore, aggregate characteristics
deeply affect the performance of asphalt pavements. Gradation is one of the important
characteristics of aggregates affecting permanent deformation of hot mix asphalt. The objective of
this research is to investigate the impact of aggregate gradation variations on various properties of
asphalt concrete mixtures. Fine, medium and coarse gradation mixtures for different aggregate types
were tested to investigate the effects of variation in the aggregate types and gradation on mix
properties. The asphalt contents of the mixes were maintained at the job mix design contents.
Properties investigated were, Marshall Stability, Marshall Flow, unit weight, air voids, and voids in
mineral aggregate. Analysis of the considering different aggregate type data revealed that the finecoarse
and coarse-fine gradation variations had the greatest impact on mix.
The research program concentrated on the Marshall Design criteria for bituminous mixes. The
results indicated that optimum asphalt content (OAC) is different due to aggregate type A coarse
grading with 25 mm maximum size is found to give the most satisfactory result from the stand point
of stability, stiffness, and voids characteristics. Test results reveal that the bituminous concrete with
WCA can give satisfactory results when they are constructed using coarse gradation.