Partial replacement of cement with rice husk ash (RHA) as filler in asphalt concrete design

Abstract

This work focused on the use of Rice Husk Ash (RHA) as filler in Hot Mix Asphalt (HMA). HMA design was carried out using Marshall Stability method. Several trial mixes with bitumen contents of 4.5%, 5.5%, 6.5% and 7.5% were produced to obtain the Optimum Bitumen Content (OBC). The investigation focuses on the partial replacement of cement with RHA using the obtained OBC in the following order 0%, 5%, 7.5%, 10%, 12.5%, 15%, 17.5%, 20%, 22.5%, and 25%. A total of forty-two (42) mix specimens were prepared, twelve (12) of these were compacted at each percentage of bitumen content to determine the OBC and 30 specimens were used to determine the optimum RHA content in terms of the HMA strength. From the Marshall Stability-flow test analysis, the sample prepared with 10% RHA as filler with an OBC of 5.5% satisfied the provision of the Standard Specification requirement by Asphalt Institute.