Tensile Strength Characteristics of Stone Matrix Asphalt with Fibre Additives

Tensile strength of Stone Matrix Asphalt (SMA) is important in pavement applications, because of the problems associated with fatigue cracking. Tensile stresses are measured indirectly by a splitting tensile test. India, being an agricultural economy produces fairly huge quantity of natural fibres such as coconut, sisal, banana etc. In this paper natural fibres are used as additives to improve the tensile strength characteristics of SMA. Marshall test is conducted for optimizing the mixtures (Control mixture-without fibre and Stabilized mixtures with fibres). Based on the studies it is inferred that the optimum fibre content is 0.3% fibre by weight of mixture for all fibre mixtures irrespective of the type of fibre. The coir fibre additive is the best among the fibres investigated. Sisal and banana fibre mixtures showed almost the same strength on stabilization. The mixtures containing fibres have higher values of indirect tensile strength at failure as compared to the control mix, indicating the improved cracking potential. Decrease in strength by water conditioning is considerable and the tensile strength ratio, an indicator of resistance to moisture susceptibility goes very much below the specification limits for SMA without any fibre. Mixtures with 0.3% fibre have more tensile strength and water resistance property than the other mixtures. A statistical analysis is performed to establish the findings of this study.