Performance Evaluation of Hot Mix Asphalt Using Cow Dung Ash as Filler

Abstract

This study evaluates the performance of Cow Dung Ash (CDA) in hot-mix asphalt. This was achieved by determining the Marshall and volumetric properties of Hot Mix Asphalt (HMA). In the HMA, cow dung ash partially replaced granite dust at varying percentages using varying bitumen content. The results obtained from the laboratory experiments indicate an increase in stability with an increase in CDA and bitumen content. Maximum stability of 11.8 kN was obtained at 40% CDA and 6% bitumen content. The flow was observed to increase with increasing CDA and bitumen content. A minimum flow of 2.7 mm was observed at 5% bitumen and 10% CDA content. The unit weight increases with an increase in bitumen and CDA content while an increase in CDA considerably decreases the void in the mineral aggregate of the mix. Additionally, the increase in bitumen and CDA content showed a decrease in air voids of modified mix. Results obtained showed that an increase in the percentage of void filled with bitumen is directly proportional to bitumen and CDA content. The Marshal properties such as stability and flow and the volumetric properties such as unit weight, Void in Mineral Aggregate (VMA), air voids and voids filled with bitumen were within the range specified by Nigerian General Specification for Road and Bridges. It can be concluded that the Marshall and volumetric properties of hot mix asphalt performed well with CDA as filler and hence, can be recommended for use in hot mix asphalt.