Suitability Of Volcanic Ash As A Filler Material In Hot Mix Asphalt

Abstract

Now a day, the scarcity of conventional filler material needs a quick solution in the production of hot mix asphalt. Hence, this study investigated the suitability of volcanic ash as an alternative filler material in hot mix asphalt. The study used purposive method of sampling materials. An experimental research method was used to investigate the partial replacement of volcanic ash in hot mix asphalt based on Marshall Mix design method. Marshall Specimens were prepared with bitumen content of 4 to 6% at 0.5% increments using crushed stone dust as a control mix. Forty five Marshall Specimens were prepared to determine optimum bitumen content. This optimum bitumen content was used to prepare Marshall Specimen with replacement of volcanic ash from 10 to 100% at 10% increments. Thirty three specimens were prepared to evaluate the effects of volcanic ash on Marshall Properties of hot mix asphalt. Marshall Immersion test method was used to determine tensile strength ratio of both filler to evaluate Moisture susceptibility of the mix. The plastic index and specific gravity of volcanic ash are 0.92% and 2.44 respectively. The chemical composition analysis indicated the volcanic ash can be classified as class – N pozzolana. All the mixes prepared with 5.15% optimum bitumen content at different proportions of volcanic ash met Marshall Criteria for asphalt concrete wearing course. Maximum stability of 11.38 kN was obtained at full replacement of volcanic ash. Marshall Immersion test resulted, tensile strength ratio of 82 and 98% for mix with crushed stone dust and fully replaced volcanic ash respectively. This result showed higher moisture resistance of volcanic ash than crushed stone dust filler in hot mix asphalt. This study concluded, all the mixes with different proportions of volcanic ash had no significant effect on performance or volumetric properties of hot mix asphalt. Hence, volcanic ash can be used for hot mix asphalt pavement either fully replacing or in combination with crushed stone dust filler. Further study on hot mix asphalt with different bitumen contents and grades, performance test (rutting) and economic analysis are recommended.