Rheological and microstructural properties of nano-composite bitumen modified by nano-alumina and low-SBS content

Abstract

This study explores a new nanocomposite-modified bitumen (NCMB) that could be more cost-effective and environmentally friendly than current options. It achieves this by combining a lower amount of styrene butadiene styrene (SBS) polymer with nano-alumina, aiming to improve performance at high and moderate temperatures. This innovative material aims to overcome the performance limitations of traditional polymer-modified bitumen (PMB). Moreover, this NCMB, which uses less modifier (SBS) and nano-alumina, paves the way for more economical and eco-friendly roads, leading to significant fuel savings. The new NCMB was prepared by mixing various nano-alumina contents (2, 3, 4, and 5 % by weight of bitumen) with low-SBS content (2.5 % by weight of bitumen) PMB. Multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) tests, further the Superpave standard method, were used to assess the rutting and fatigue cracking resistance of PMB and NCMBs. Field emission scanning electron microscopy (FESEM) with elemental analysis by energy dispersive X-ray spectroscopy map (EDS) techniques and Fourier-transform infrared spectroscopy (FTIR) was used to investigate the microstructural and elemental characteristics of NCBBs. The results demonstrated that adding nano-alumina to low-SBS content PMB significantly enhanced both the storage stability and its durability over time (i.e. aging resistance) of the NCMBs. The MSCR test results showed that samples with 5 % nano-alumina had a rutting resistance higher than the PMB, up to 31 %. The NCMB samples with 4 % nano-alumina demonstrated a significant improvement in fatigue resistance of up to 67 %. The FTIR results revealed a 64 % improvement in aging resistance for NCMBs containing 3 % nano-alumina compared to the PMB. The storage stability values increased for all NCMB types and reached 62 % for the samples with 5 % nano-alumina. Overall, adding nano-alumina to low-SBS content PMB led to a remarkable improvement of rheological properties at intermediate and high temperatures and a stable system under storage conditions with high anti-aging resistance.