Laboratory evaluation of the effect of styrene-butadiene-styrene - montmorillonite nanocomposite on rheological behavior of bitumen and performance of stone matrix asphalt mixtures

This study was performed to evaluate moisture susceptibility of different stone matrix asphalt (SMA) mixtures modified with styrene-butadiene-styrene (SBS) and nanoclay. Different samples with various percentages of nanoclay (2, 3, 4, and 5%) and SBS (0 and 5%) based on the weight of the bitumen were prepared. Rheological and mechanical properties of the modified bitumen samples were also investigated using bitumen conventional evaluation tests and dynamic shear rheometer, respectively. Fourier transform infrared spectroscopy measurement was conducted for obtaining the microstructure distribution of modified asphalt binders. The chemical properties of aggregates were analyzed with X-ray fluorescence. Moisture susceptibility of the modified asphalt mixtures was evaluated using three different methods, including resilient modulus ratio, tensile strength ratio, and fracture energy ratio tests. Based on the obtained results, using nanoclay as the secondary modifier could improve mechanical properties of the SMA asphalt mixture.