Laboratory Evaluation on the Use of Natural Fibre in Gap-Graded Asphalt Mixtures

Abstract

Stone Matrix Asphalt (SMA) is a gap-graded mixture that consists of a high concentration of coarse aggregates, which imparts strength and rut resistance and a high binder content, making the mixture durable. The high binder content mortar consists of fine aggregates, filler, bitumen and stabilising additive. One of the limitations of SMA is it suffers from draindown of binder mortar which can be reduced by adding a mineral fibre, natural fibre or synthetic fibre. The addition of a stabilising additive not only controls the draindown but also improves the tensile strength because of the network of fibres in the mixture. In the present study, an attempt is made to determine the effect of Areca fibre, a natural fibre abundantly available in the southern Indian region. A comparison between two SMA mixtures prepared with and without stabilising additive is made. The Superpave mix design method was adopted, and tests such as draindown, fatigue, rutting and moisture-induced damage properties such as tensile strength ratio (TSR) were evaluated. The results indicate that the mixture with Areca fibre effectively controls the draindown and satisfies the volumetric and mix design criteria as per IRC SP 79. However, the performance of SMA without stabilising additive was better than the mixture with the stabilising additive with respect to resistance to rutting, fatigue and moisture-induced damage. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.