Partial replacement of filter cake powder as a filler in hot mix asphalt

Abstract

The road pavement construction industry of consumes a large amount of virgin aggregate and Solid waste material has impacts on environmental problem. Therefore, this investigation aims to explore the suitability of filter cake powder as a filler in hot mix asphalt. FCP is taken from alum factory from awash melkasa town. The study used purposive method of sampling materials. Marshall mix design method was used for designing both conventional and filter cake powder mixtures. For conventional four percent of bitumen content (4.3,4.8,5.3 and 5.8%) and three crushed stone filler content 5.5,6.5 and 7.5% were used to determine optimum bitumen content and optimum filler content. Optimum bitumen content and optimum filler content was used to prepare Marshall Specimen with mixture of filter cake by replacement 0,10,20,30,40 and 50%. Marshall Immersion test method was used to determine tensile strength ratio of both fillers (conventional and filter cake) to evaluate Moisture susceptibility of the mix. The results show that adding filter cake by partially in hot mix asphalt improves its mechanical properties. The optimum filter cake ratio gives the maximum stability of HMA is at 30% FCP. The values of stability, flow, bulk specific gravity, voids filled with asphalt, air voids and voids filled in mineral aggregates at 30% optimum filter cake powder content were, 11.49 kN, 3.21 mm,2.253 g/cm3, 72.7%, 3.84%, and 14.06%, respectively. While the 0,10,20,40 and 50% FCP fulfill the requirements of Ethiopian Road Authority and Asphalt Institute standard specifications. Marshall Immersion test resulted, tensile strength ratio was 83.6 and 90.2% for mix with fully crushed stone dust and replaced filter cake at 30% respectively. Result showed that resistance of moisture induced damage of filter cake is higher than crushed stone dust filler in hot mix asphalt. This study concluded, all the mixes with partial replacement of filter cake has significant effect on performance of hot mix asphalt concrete production. Therefore, based on this study, filter cake powder can be considered as an alternative to conventional filler in hot mix asphalt. The amounts of waste filter cake can be removed from factory and significantly environmental damage can be reduced