Evaluation of the Effect of Mixing Conditions of Micro-Silica Modified Asphalt Binder

Abstract

The aim of this study was to improve an effective approach to the processing of asphalt binder modified with micro-silica particles. Various mixer type (mechanical and high shear), revaluation rates (2000, 4000 and 6000 rpm), and two mixing time (30 and 60 minutes), were adopted. Three micro-silica contents 2%, 4%, and 6% by weight of asphalt cement were added. The asphalt binder was prepared at temperature of 140 °C. Comparisons were made to evaluate the properties of the modified asphalt binder such as penetration grade, softening point temperature, temperature sensitivity, rotational viscosity and ductility. Results of this study showed that the use of micro silica as a modifier was helpful in enhancing the physicals properties of the asphalt binder. In general, it was found that the penetration value decreased and softening point temperature, as well as the viscosity value, increased and the temperature sensitivity was improved. Furthermore, high shear mixing was more practical particularly to achieve a good dispersion of micro silica particles into asphalt binder and obtained a homogenous composite binder. Finally, the tested specimens showed 6% of micro silica was adequate to improve the physical properties of asphalt and become more suitable for constructing the highway pavements in hot weather conditions.