The study focused on the evaluation of effects of steel slag and fly ash on the properties of asphalt concrete.
Steel slag and fly ash with conventional materials such as aggregate, fillers and bitumen were used in this
study. Experimental test to ascertain the physical properties of these materials were performed. Cylindrical
samples of asphalt concrete were produced by mixture of bitumen, aggregate, filler and varying proportions
of steel slag and fly ash at 2%, 4%, 6% and 8% to partially replace the conventional materials (coarse, fine
aggregate and filler) with different bitumen content of 5%, 5.5%, 6%, 6.5% and 7% respectively. The marshal
stability and flow were obtained. The result of steel slag modified asphalt concrete showed that optimum
stability of 13.00KN was obtained at bitumen content of 6.0% in varying proportion of 8% while the optimum
flow value of 2.8mm was obtained at 6.0% of bitumen content in varying proportion of 8%. The result of fly
ash modified asphalt concrete showed that optimum stability of 10.70KN was obtained at 8% varying
proportion of fly ash while optimum flow value of 2.8mm was also obtained at 8% varying of proportion of
fly ash respectively. The stability and flow values obtained lie within the recommended specifications (Not
less 3.5KN for stability and 2mm - 6mm for flow) in accordance with Nigeria General Specification for Road
and Bridges (NGSRB), 2016 specification. The study concluded that the two modifiers utilized enhanced the
properties of asphalt concrete and showed that the modifiers used have the potential to reduce the cost of road
developments.
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