Improving the Rutting Resistance of Bitumen and Asphalt Mixtures using Polyurethane/Carbon Nanotube Composites

The surface layer of pavements, usually made of bitumen, is crucial for performance, especially in preventing rutting that affects pavement quality and lifespan. The performance of asphalt mixes in road construction largely depends on the bitumen used. Enhancing bitumen properties helps address the shortcomings of pure bitumen, thereby improving asphalt pavement performance, quality, and longevity. In this research, to enhance the properties of bitumen and asphalt mixes, the effect of using a nanocomposite modifier of polyurethane with hydroxyl-functionalized multi-walled carbon nanotubes (OH-MWCNTs) was investigated. First, isocyanate-terminated polyurethane prepolymer (NCO-PP) was synthesized and incorporated with OH-MWCNTs. According to Fourier transform infrared (FT-IR) analysis, the successful synthesis and also presence of nanoparticles in the matrix were confirmed. Next, based on thermogravimetric and tensile analysis, the nanocomposite containing ۱.۵ wt.% OH-MWCNT was chosen as the optimum composition. By performing rotational viscosity (RV), multiple stress creep recovery (MSCR), and dynamic creep tests, it was found that the asphalt based on modified bitumen samples had improved properties, with the polymer nanocomposite (PNC)-modified samples showing better results. Using the synthesized modifiers, not only the rutting resistance was improved, but the traffic rating was enhanced by ۲ grades. Then, by performing the scanning electron microscopy (SEM) test and examining the morphology of the modified bitumen samples, a uniform distribution of the polymer nanocomposite in the entire matrix was observed. Thus, it could be expected that the application of nanocomposite modifiers in asphalt pavements can largely prevent damages resulting from rutting.

کلیدواژه ها:

Bitumen Modification ، Polyurethane ، Rutting ، Polymer nanocomposite ، Carbon nanotubes