Expansion inhibition of steel slag in asphalt mixture by a surface water isolation structure

Abstract

To inhibit volume expansion of steel slag and improve pavement performance of steel slag asphalt mixture, a surface water isolation structure was proposed by employing three surface treatment approaches. Properties of the surface modified steel slag were tested including water absorption, expansion ratio, crush value and adhesion. X-ray diffraction, X-ray fluorescence and scanning electron microscope were used to analyse the physical and chemical properties of steel slag. Results showed that three approaches could reduce the volume expansion of the surface modified steel slags at a certain extent, and the silicone waterproof agent had the best treatment effect, with expansion ratio reduced by 34%. Subsequently, three asphalt mixtures (surface modified steel slag, original steel slag and basalt) were prepared. Rutting test, low-temperature bending test, mixture immersion expansion test, Marshall test and freeze–thaw split test were achieved to determine their pavement performances. Compared with control groups, the high-temperature performance and water stability of the asphalt mixture composed of surface modified steel slag had significant enhancement. The dynamic stability increased by 20% and the 72 h mixture expansion ratio decreased by 44%. This surface water isolation structure is valuable for inhibiting the volume expansion of steel slag and improving the performances of steel slag asphalt mixture.