Experimental Investigation to Quantify the Fatigue Damage of Unmodified and Modified Bitumen and Bituminous Mastic

Abstract

Bituminous material is subjected to repeated loading, micro-cracks form within newlinethe material. These micro-cracks further grow and coalesce, inducing fatigue and damage. newlineThe crack propagation occurs through the binder and filler phase in the aggregate. It is newlineunderstood that both the presence of binder and filler contribute significantly to the fatigue of newlinethe bituminous pavement. Therefore, laboratory investigation was conducted on bituminous newlinebinder and bituminous mastic in oscillatory testing mode to determine the point of damage newlineonset using different post-processing methods. From a detailed literature review, it is also newlineunderstood that the different methods of post-processing assume the material s response to newlinebe linear. As a consequence, it becomes mandatory to restrict the testing within the linear newlineregime of loading. However, it is also understood that the sample may take a long duration newlineof time to damage when sheared in the linear regime of loading. Hence, to reduce the time newlineof testing within a reasonable range, it is mandatory to use higher strain in the nonlinear newlineregime. In such a case, there are two constraints to be addressed. One is related to the small newlineamplitude oscillatory shear (SAOS) test protocol. The conventional SAOS test protocol newlineuses strain amplitude in the linear regime of shearing. With the oscillatory shear in the newlinenonlinear regime, there will be a higher harmonic contribution which cannot be measured newlineusing the SAOS test protocol. Even within the linear regime of shearing, as the damage newlineprogresses, the higher harmonic contribution in the shear stress may dominate and hence newlineone cannot use the SAOS test for the fatigue damage characterization of the bituminous newlinematerial. In this research work, the use of large amplitude oscillatory shearing (LAOS) newlinefor the fatigue damage characterization of binder and mastic was explored