Effect of polymers and micro fibres on the thermo-chemical and rheological properties of polymer modified binders

Polymer-modified bitumen provides superior thermo-chemical and rheological properties. This study focuses on the correlation between the thermo-chemical and rheological characteristics of bitumen modified with five different polymers in addition to neat bitumen. The polymers include an amine-wax-based additive, thermoplastic elastomers, a system of elastomers and microfibres, plastomers and a system of plastomers and microfibres. The chemical compositions were investigated using Fourier-transform infrared spectroscopy (FTIR), while the thermal behaviour was studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The modified bitumen’s rheological performance was analysed using frequency sweep, linear amplitude sweep (LAS), and multiple stress creep and recovery (MSCR) tests. Rheological properties showed that the combination of fibre and polymers improved the thermal susceptibility of the bitumen at all ranges of temperature compared to other blends that only included single polymers. FTIR spectroscopy suggests that the polymer modification resulted in successful blending and active cohesion between the polymer matrix and bitumen. TG/DTG analysis confirmed that the modified blends exhibited greater thermal stability than neat bitumen. Glass transition temperature (Tg) was obtained from DSC to predict the polymers’ low-temperature rheological properties whereas, degree of crystallinity and melting point showed the intermediate and high temperature properties of the binders.