Fatigue Analysis of Coir Powder Modified Bitumen Using Linear Amplitude Sweep Test

The fatigue resistance of the asphalt binders is significant in the fatigue performance of asphalt pavements. Previously, the Super-pave specification parameter |G*|sinδ was identified and used for rating the asphalt binders based on their fatigue resistance. However, in ensuing research works, it was found that this parameter does not relate well with the accumulation of fatigue damages under strain-controlled conditions and significant efforts had been carried out to accurately measure and characterize the fatigue resistance of binders in a way that had been suitable for inclusion in binder specifications. This led to the suggestion of a new binder fatigue test using the linear amplitude sweep test in the DSR (dynamic shear rheometer) to find out the number of cycles to fatigue failure (Nf) and the effectiveness of this parameter to consider as the criterion for rating the binders based on their fatigue resistance. This study uses the Linear Amplitude Sweep (LAS) test at a temperature of 25°C in which the amplitude of the applied load was continually increased from 0 to 30% over the course of 3100 cycles to accelerate the growth of damage on the short term and long-term aged binders. This study deals with the fatigue analysis of VG30 bitumen with and without varying percentage (0% to 1.2%) of coir powder. Different laboratory tests such as penetration value, softening point, ductility and viscosity have been performed on all the samples. Fatigue performance parameters of binders with and without coir powder were also evaluated. Results of this study showed that the addition of the additive increases the fatigue life and aging resistance of the binders. The results revealed that the addition of additive enhances the binder properties. Besides, the results indicated that the elastomeric modified binder gave the best performance in fatigue.