Laboratory Evaluation of the Performance of Hot Mix Asphalt Made with Kaolin as a Filler with the Superpave Aggregates Gradation

Mineral fillers and different granulations of aggregates have a great effect on the mechanical properties of asphalt pavements. In this research, the effect of non-conventional materials called kaolin and superpave granulation on Marshall properties, moisture sensitivity and permanent deformation in asphalt mixtures was investigated. The chemical composition of kaolin shows that the total amount of silicon dioxide (SiO2), iron oxide (Fe2O3) and aluminum oxide (Al2O3) was 63, 24.1 and 2.84%, respectively. The physical properties of kaolin were determined on specific gravity and the plastic index was 2.62 and 3.24, respectively. Based on the characteristics of the studied area and temperature, bitumen grade with penetration of 60/70 is selected. Hot mix asphalt 1 (HMA) samples of three different superpave granulations with conventional crushed stone filler (CSD) 2 with different ratios (5.0, 6.0, and 7.0%) and five different bitumen contents (4, 4.5, 5, 5.5 and 6) was prepared. %. Warm mix asphalt with 5.0% CSD was chosen as the control mixture. The conventional filler was replaced with kaolin at different replacement rates (0, 10, 20, 30, 40 and 50%) based on the control mix with 5% CSD and 5.1% optimum bitumen content (OBC)3. A replacement rate of 30% kaolin provides Marshall properties and better resistance to moisture sensitivity. The results of the tests showed that the use of kaolin on HMA met the criteria set in the specification as a filler with superpave gradation up to 30% of the replacement of conventional filler in HMA.