Performance of Steel Slag as Constituent Material in Asphalt Concrete

Abstract

Increase in urbanization necessitate infrastructural facilities among which is road development. However, the use of limited and non-renewable constituents’ materials such as bitumen, aggregate and filler lead to increasing cost of road construction,maintenance and rehabilitations. Thus, exploitation of alternative material (waste or by-products) that can improve the properties of pavement is important. The physical properties of steel  slag (SS), aggregate and bitumen was analysed, while the chemical composition of SS was determined with the aid of X-ray diffraction and  X-ray fluorescence. A cylindrical sample of the composite mixture of asphalt concrete was produced using varying proportion of steel slag (SS) at 2%,  4%, 6% and 8% to partially replace the conventional aggregates. Marshall Stability and flow test was performed on the sample produced, while  the microstructural analysis of the sample was done using Scanning Electron Microscope (SEM). The marshal stability values obtained were 7.45 KN,  7.75 KN, 8.63 KN, 9.82KN and 11.0 KN for 2%, 4%, 6% and 8% replacement with SS. Comparing with criteria for the Marshal mix design method  provided by Asphalt Institute (1997); 4%, 6%, and 8% of SS can be used as coarse and fine aggregate in heavy traffic roads while 2% is appropriate  for medium traffic road. Hence SS can be used as partial replacement of aggregate (coarse and fine) in asphaltic concrete to improve the  performance of the mix and reduces the cost of road construction.