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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.

The study aimed to assess the suitability of ceramic waste aggregate and recycled asphalt pavement aggregate as an alternative for base course material. An experimental research design method and Non-Probability sampling techniques were used. The comparative analysis of ceramic waste aggregate and recycled asphalt pavement aggregate were blended with crushed stone aggregate at different proportions by weight and their laboratory result was compared with standard specifications. The study results shown that the aggregate crushing value (ACV) for neat Crushed stone aggregate (CSA) and Recycle asphalt pavement (RAP) are 19.20% and 8.20% respectively and the blended CSA with 10%, 20%, 30%, 40% and 50% of RAP were 18.20%, 16.4%, 15.90%, 14.40%, and 13.10% respectively. Similarly, a 24.32% - 12.06% for Los Angeles abrasion (LAA) and 18.50% - 12.60% for aggregate impact value (AIV) were found to the lower and higher value in the range of the test result. The CBR test for a different proportion of RAP (10% - 50%) blended with CSA was also conducted and an economically acceptable result of 104.20% was found at 30% RAP mix at 98% maximum dry density (MDD). Additionally, the California Bearing Ratio (CBR) test result for 100%RAP at 98%MDD was 49.10%. On the other hand, the experimental tests were conducted on different proportions of Ceramic West aggregate (CWA) (10%, 20%, 30%, 40%, and 50%) which satisfy the principal mechanical properties of aggregate materials. The ACV result for neat CWA is 26.70% while the blended CWA- CSA aggregate was tested with 10%, 20%, 30%, 40%, and 50% of CWA with its complement of CSA as indicated and at 20% CWA replacement of CSA test results were (21.60%, for ACV), (26.31% for LAA), (106.9 for CBR) and (20.60 for AIV). For this investigation an economically acceptable results were achieved by satisfying the Ethiopian road authority (ERA) standard specification limit at 20% CWA and 30% RAP blended with CSA for base course construction material.

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