Studying the Effect of Mineral Filler Type of Hot Mix Asphalt on Optimum Asphalt Content and Marshall Properties

Abstract

ABSTRACTThe filler plays a major role in the properties and behavior of asphalt paving mixtures.Mineral filler were originally added to hot mix asphalt (HMA) to fill the voids of theaggregate gradation and to reduce the voids in the mixtures. The filler used in the asphaltmixtures to affect the mix design properties, especially the optimum asphalt content. Tomeet the objectives of this research, available local materials were used including asphaltcement, aggregate and mineral fillers. In this research, limestone dust, Portland cementand silica fume were used as a mineral filler. Three types of mixtures were prepared. Thefirst type included limestone dust, the second type included Portland cement and the lasttype included silica fume. The optimum asphalt content of each type of mixtures wasdetermined using Marshall Mix design method. Optimum asphalt content was 4.9 % formixture type I and mixture type II and 5.1% for mixture type III. The result of optimumasphalt content showed that this percentage do not change when using Portland cementas a mineral filler if compared to mix with limestone dust, while it was increases whenusing silica fume as a mineral filler instead of limestone dust. The results of Marshalltest showed that Marshall Stability was increased by 37.11 % when using Portlandcement as a mineral filler instead of limestone dust, while it was decreased by 4.05 %when using silica fume as a mineral filler instead of limestone dust. The results alsoshowed that the bulk density increases when using Portland cement as a mineral filler ifcompared to mix with limestone dust, while when using silica fume as a mineral fillerinstead of limestone dust, slight decrease in the bulk density is occurred. Also, theresults revealed that the Air voids were decreased when using Portland cement and silicafume as a mineral filler if compared to limestone dust