Effect of Silica on Hot Mix Asphalt Mixture

Abstract

Abstract The hot asphalt mixture is the main layer in flexible paving as it is exposed to traffic loads and environmental factors which require high resistance, high durability and good stability to avoid structural deformities that leading to functional and structural failure. In the past few years. Several tests have been carried out on the prepared and compact specimens such as density testing, indirect tensile strength (exposed to freezing and thawing conditions and not exposed), stability and flow as well as non-destructive test using sound waves. The results of the tests showed that the specimens, containing silica fume as apart from filler aggregate (Portland cement), have high Marshall stability-flow and extra resistance to tensile strength than conventional specimens that contain just ordinary Portland cement. All results found to be satisfied the Iraqi specifications adopted for roads and bridges. Calculation of optimum silica fume content has achieved for all tests in order to find overall optimal content which was 4.2%.