Laboratory Performance Evaluation of Hot Mix Asphalt Mixture Using Belessa Kaolin as a Filler with Superpave Aggregate Gradation

Mineral fillers and different aggregate gradations have a great effect on the mechanical property of asphalt concrete pavements. In this research, the effect of nonconventional material so-called Belessa kaolin and Superpave gradation on marshal properties, moisture susceptibilities, and permanent deformation in asphalt mixtures was investigated. The chemical composition of Belessa kaolin shows that the total content of silicon dioxide (SiO2), iron oxide (Fe2O3), and aluminum oxide (Al2O3) was 63%, 24.1%, and 2.84%, respectively. The physical properties of Belessa kaolin were conducted on specific gravity, and the plastic index was 2.62 and 3.24, respectively. Based on the study area characteristics and temperature, a bitumen grade of 60/70 penetration is selected. Hot mix asphalt (HMA) specimens were prepared from three different Superpave gradations with conventional filler crushed stone dust (CSD) of different proportions (5.0, 6.0, and 7.0%) and five different bitumen contents (4, 4.5, 5, 5.5 and 6%). A hot mix asphalt with 5.0% of CSD was selected as the control mix based on Ethiopian Road Authority (ERA) standard specifications. The conventional filler was replaced by Belessa kaolin at different replacement rates (0, 10, 20, 30, 40, and 50%) on the basis of the control mix with 5% CSD and 5.1% optimum bitumen content (OBC). The replacement rate of 30% of Belessa kaolin provides better marshal properties and resistance to moisture susceptibility. The results of the experiments indicated that the use of Belessa kaolin on HMA has fulfilled the criteria specified on the specification as a filler with Superpave aggregate gradation up to 30% replacement of conventional filler in HMA.

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