Laboratory evaluation of use of areca fibres in SMA mixes

One of the problems associated with Stone Matrix Asphalt (SMA) mixes is the drain down of binder mortar during production, transportation and placement of the mixes. A commonly adopted method to control the drain down is to add a stabilising additive such as natural, synthetic or mineral fibres to the mixture, which is also known to improve the mechanical and volumetric properties of SMA. The present study evaluates the feasibility of using areca fibres extracted from areca husk in SMA as a stabilising additive. Three SMA mixtures were prepared with Viscosity Grade VG 30 bitumen using areca fibre (SMA-AF), coconut fibre (SMA-CF) and cellulose fibre in pelletised form (SMA-PF) and their performance was compared with a control SMA mixture prepared using Polymer Modified Bitumen (SMA-PMB). The prepared SMA specimens were evaluated for volumetric and Marshall properties, workability characteristics, Indirect Tensile Strength (ITS), fatigue, rutting and moisture susceptibility. The drain down test results indicated that the fibres controlled the drain down, and the optimum fibre content was 0.3% for the mixes with fibres. All the mixtures satisfied the requirements of SMA per IRC:SP 79-2008. The statistical analysis conducted revealed that the fibre type had a significant effect on the properties of SMA mixes. The SMA-PMB and SMA-CF mixes required the least and the highest energy for compaction. Among the mixes with natural fibres, SMA-AF performed better than SMA-CF.