Effect of Nano-modified Binder on Fracture Properties of Warm Mix Asphalt Containing RAP

Low-temperature stripping, medium-temperature fatigue cracking and high-temperature rutting are prominent premature failures in flexible pavements. The premature failures and the pavement durability aspects can be prevented with the use of modified binders, admixtures, inclusion of Recycled Asphalt Pavement (RAP), innovative mix design practices, which shall be achieved by aggregate packing characteristics and a few other technologies are also in place. Warm Mix Asphalt (WMA) and Cold Mix Asphalt technologies are being extensively used as an alternative for conventional Hot Mix Asphalt (HMA) technology, so as to make the construction process less energy intensive, lowering the carbon emissions and thereby ensuring the sustainability.In the current investigation, the cracking resistance of bituminous mixes was examined with the laboratory prepared Sasobit- and nano-powder-modified binder. In addition, the 20 percent of coarse aggregates were replaced with RAP aggregates for achieving the sustainability aspect. First, the physical properties of conventional, and Sasobit-modified binder were evaluated. Later, mechanical properties of mixes were evaluated with varying nano-powder content for their fracture properties using Semi-Circular Bending (SCB) test. It is observed that the bituminous mix prepared with 3% Sasobit, 5% nano-powder, and 20% RAP has exhibited a considerable increase in resistance towards cracking at intermediate temperature when compared with mixes prepared with conventional and Sasobit-modified binders. Similar improvements were observed for Tensile Strength Ratio (TSR), resilient modulus and rut depth. Scanning Electron Microscopy (SEM) images have revealed that the Sasobit and nano-modification resulted in the amorphous nature of binders. Further, the X-Ray Diffraction (XRD) studies have revealed semi-crystalline nature and the average crystallite size of Sasobit- and nano-modified binders were slightly less when compared with conventional binder after subjecting to short-term aging.