Influence of Post - Processing Methods for Ranking of Fatigue Life of Bituminous Mixture

In this study, four point beam tests were conducted on bituminous mixture sample pertaining to Bituminous Concrete (BC) grade II as per MORTH specification. The samples were produced using unmodified binder and modified binders. Two types of modified binders, one with crumb rubber and other with polymer were used. A beam sample of size 450×150×160 mm was fabricated using PReSBOX shear compactor with 4% air voids. This sample was cut into samples of size 380×63×50 mm and tested in a four point beam bending equipment. Tests were performed in a controlled displacement mode using sinusoidal waveform with strain amplitude of 200, 400 and 600 microstrain and at a frequency of 10 Hz. The entire test was carried out at 0°C. The load and displacement data as a function of time for every cycle was recorded at the time interval of 1/100th second. The stiffness modulus, normalized stiffness modulus, phase angle, energy dissipation and cumulative energy dissipation were calculated from the load-displacement data and fatigue life was calculated using all the aforementioned approaches. It was observed that considerable disparity existed between the results. The present investigations threw light on the difference in the fatigue life of the bituminous concrete mixture obtained using these different methods of analysis. Also, the ranking of different bituminous mixture for unmodified and modified binders based on the fatigue life was carried out.