Characterisation of Pyro-oil Modified EVA and SBS Bitumen Using Variation in MSCR Test

The multiple stress creep and recovery (MSCR) test is the most commonly used method to characterise the rutting resistance of bituminous binders. However, the stress levels of 0.1 and 3.2 kPa, employed in this test as per ASTM D7405 are insufficient to represent the non-linear viscoelastic behaviour of modified bitumen under practical traffic conditions. Therefore, the modified binders are required to be characterised at higher stress levels. The present study intended to analyse the permanent deformation behaviour of high-density polyethylene (HDPE) pyro-oil modified bitumen using variation in stress levels of the MSCR test. The base bitumen VG30 is modified using ethylene vinyl acetate (EVA) and styrene butadiene styrene (SBS) polymers. The base and polymer modified bitumen are further modified with HDPE pyro-oil which was obtained from the pyrolysis of HDPE plastic waste. MSCR test with additional stress levels of 5, 6.4, 10, 12.5, and 25 kPa is used to characterise the base, polymer, and pyro-oil modified bitumen. It was found that higher stress levels than the standard 3.2 kPa are required to obtain the non-linear behavior of polymer modified bitumen. The addition of pyro-oil increased the rutting resistance of EVA modified bitumen, whereas the same is found to be decreased for SBS modified bitumen.