Evaluation of an MDC-19 Asphalt Mix with Partial and Total Replacement of Fines by Rice Husk Ash

Abstract: This study evaluates the performance of an MDC-19 asphalt mixture with partial and total replacement of fines by rice husk ash (RHA) using the Marshall methodology. The aim was to explore the potential of RHA as a sustainable and environmentally friendly alternative in the construction of flexible pavements. In this investigation, asphalt mixtures were produced by replacing conventional fines with RHA in different proportions: 30%, 50%, 80%, and 100%. These modified mixtures were subjected to laboratory tests to assess their mechanical properties, including stability, flow, void percentage, and resistance to wear.

The use of RHA as a filler replacement was motivated by the need to incorporate more sustainable practices into pavement design, given the increasing demand for environmentally responsible construction materials. Rice husk ash is an agricultural byproduct that contains high levels of amorphous silica, which is known to enhance the cohesive properties of asphalt mixes. By substituting mineral fillers with RHA, the study aimed to not only improve the technical performance of asphalt mixtures but also to offer a solution to the environmental issue of rice husk disposal.

The results of the tests showed that mixtures containing RHA exhibited improved stability and flow compared to conventional mixtures. The stability of the asphalt mixtures increased with higher RHA content, suggesting that the ash contributes to better cohesion between the particles, thus enhancing the strength of the mixture. The void percentage also decreased as RHA content increased, indicating a more compact and dense mixture. Moreover, the wear resistance of the modified mixtures was superior to that of the control mixture, particularly in the specimens with higher RHA content.

In terms of sustainability, the use of RHA as a filler in asphalt mixtures presents significant environmental benefits. Rice husk is a renewable resource, and its conversion into ash for use in pavements helps reduce the volume of waste generated by the rice industry. Furthermore, the substitution of mineral fillers with RHA reduces the consumption of natural resources typically used in asphalt production, promoting a more sustainable approach to pavement construction.

Compared to conventional asphalt mixtures, the modified mixtures showed enhanced mechanical properties, particularly in terms of strength, durability, and wear resistance. These improvements make RHA-modified asphalt mixtures a promising option for use in high-traffic roads and other demanding applications. The study concludes that the partial and total replacement of fines with RHA is both technically feasible and environmentally advantageous. The findings support the use of RHA as a sustainable alternative in the road construction industry, contributing to the development of more durable pavements while addressing environmental challenges related to agricultural waste disposal.

This research highlights the potential of rice husk ash to improve the performance of asphalt mixtures while promoting sustainability in construction practices. Future studies could explore the long-term performance of RHA-modified pavements in real-world conditions and evaluate their economic viability on a larger scale.