Bituminous mixes are made up of coarse aggregate, fine aggregate, filler, and binder. In Hot Mix Asphalt (HMA), all these materials are heated before mixing, laying, and compaction. HMA can be of two types: Dense Graded Mixes (DGM) like Bituminous Concrete (BC), and Gap Graded Mixes like Stone Matrix Asphalt (SMA). SMA requires stabilizing materials like fibres to stop binder drain down.

This study focuses on evaluating the performance of BC and SMA when natural sisal fibre, which is easily available locally, is added. The aim was to see how sisal fibre affects the strength and durability of these mixes. The aggregates used followed MORTH grading, and the binder content was varied from 4% to 7%. Sisal fibre was added in different amounts, from 0% to 0.5% of the total mix. Fly ash, which gave good strength results, was used as filler.

The Marshall Method was used to find the best binder and fibre content. The Optimum Fibre Content (OFC) was found to be 0.3%, while the Optimum Binder Content (OBC) was 5% for BC and 5.2% for SMA.

Performance tests such as drain down test, indirect tensile strength test, and static creep test were carried out on the mixes prepared at their OBC and OFC. The results showed that adding sisal fibre improved the stability, reduced binder drain down, and increased tensile strength of the mixes. SMA mixes performed better than BC in terms of strength and resistance to deformation.