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Considering the characteristics of steel slag, the effective relative density of steel slag was measured by the impregnation method. By the volume substitution method, the asphalt mixtures with different steel slag content were prepared for replacing the coarse aggregates. According to the technical requirements of the ultra-thin friction course, the road performance and the function characteristics of the steel slag asphalt mixture were evaluated. The test results show that with the increasing of steel slag content, the performance indexes of dynamic stability, maximum tensile strain and tensile strength ratio of asphalt mixture are increased with latter decreasing. When the steel slag content is 50%, the comprehensive performance of asphalt mixture is the best. With the increasing of the placement time of test specimens, the high temperature performance index of the steel slag asphalt mixture is increased slightly, while the low temperature crack resistance index and water stability index are decreased. The skid resistance and abrasion resistance of asphalt mixture are significantly improved with the addition of steel slag. The impermeability of the mixture is reduced, while the water seepage coefficient values of several steel slag asphalt mixtures can still meet the requirements of the standard test methods of bitumen and bituminous mixtures for highway engineering (JTG E20—2011). [ABSTRACT FROM AUTHOR]

The indoor tests were used to investigate the effects of carbon nanotubes on the rheological properties of high temperature bitumen and the fracture toughness of mixture by comparing base asphalt with SBS modified asphalt, and the mechanism was explained by differential scanning calorimetry and scanning electron microscopy. The results show that carbon nanotubes can significantly improve the anti-shear and high-temperature anti-rut properties of asphalt and improve the construction temperature of asphalt mixture. When the content of carbon nanotubes is more than 2.0%, the rutting factor does not increase obviously. When the temperature reaches above 177 °C, bitumen is very easy to aging. Hence the maximum content of carbon nanotubes is 2.0%. The addition of carbon nanotubes decreases the endothermic peak at 150 °C, which can improve the thermal stability of asphalt greatly. Compared with the matrix asphalt and SBS modified asphalt, the addition of carbon nanotubes can physically adsorb and reinforce the asphalt and greatly improve the fracture toughness of asphalt mixture. [ABSTRACT FROM AUTHOR]