Volume 40, Issue 7 (December 2012)
Aging Behaviour and Mechanism of SBS-Modified Asphalt
The aging behaviour and mechanism of styrene-butadiene-styrene (SBS)-modified asphalt has been investigated based on laboratory tests in this study. Rolling thin-film oven (RTFO) test and pressure-aging-vessel (PAV) test were conducted to prepare aged SBS-modified asphalt. Conventional property tests, including penetration, soften point, and ductility, as well as elastic recovery and SHRP property tests, including viscosity, dynamic shear rheometor (DSR) and bending-beam rheometer (BBR) tests, were mainly used to analyse the aging behaviour of SBS-modified asphalt. Then Fourier transform infrared spectroscopy (FTIR) and gel-permeation chromatography (GPC) tests were conducted to capture the aging mechanism of SBS-modified asphalt. The testing results indicated that SBS-modified asphalt has similar aging behaviour as base asphalt but better performance and anti-aging ability because of the existence of the SBS modifier. However, it is still inevitable that SBS-modified asphalt becomes aged because of thermal oxidation. The aging of SBS-modified binder consists of two parts: (i) the oxidative aging of the asphalt components, and (ii) the degradation of the SBS modifier. Because of the protective effect between asphalt and SBS polymer, the aging degrees of asphalt and SBS polymer were lower than those aged independently.