Evaluating the effects of the wet and simple processes for including carbon Nanotube modifier in hot mix asphalt

Main goal of this study is comparing conventional hot mix asphalt (HMA) with carbon nanotube (CNT) modified-HMA and finding optimized carbon nanotubes content, experimentally. First, two different mixing methods were investigated to find the best one to mix CNTs in asphalt binder as homogeneous as possible. Second, morphology of raw CNTs and CNTs dispersed in asphalt binder was investigated by a scanning electron microscope (SEM). Third, some tests including indirect tensile strength (ITS) test, rotational viscosity (RV) test, resilient modulus test and indirect tensile fatigue (ITF) test were conducted to evaluate properties of modified and unmodified asphalt binders and asphalt mixtures. Regarding SEM test results, it was found that wet-mix method led to more homogeneous mixtures. According to RV test results, the viscosity of CNT-modified asphalt binder produced by wet-mix method is less than the maximum range. It was observed that modification with CNTs led to higher stiffness and consequently improved rutting resistance, particularly when 0.5% to 1% CNT is used. CNT-modification also improved resistance of HMA specimens against fatigue phenomenon, particularly, at low temperatures.