Bitumen modification with recycled materials: a comparative study

Abstract

The main goal of this research was to compare the modification ability of two different types of bitumen modifiers. Commonly these modifiers are classified as recycled materials since the first is rubber coming from scrap tires also known as crumb rubber and the second is a polymer coming from green house films disposal. Therefore, this paper presents the effect and degree of modification of a 50/70 penetration grade bitumen in terms of rheological properties, PG (performance grading) system and morphology. Conventional tests such as penetration grade, Ring-and-Ball softening point and storage stability were performed. Rheological properties of the modified blends were characterized in terms of dynamic mechanical analysis through frequency sweep tests using the dynamic shear rheometer (DSR). The morphology of the samples is investigated by means of fluorescent light optic microscopy. The results of classic tests showed that adding these waste materials reduced penetration, temperature susceptibility, and increased the softening point, elastic recovery. Basic understanding of fatigue cracking and rutting behavior is determined from the data obtained with DSR including mainly complex shear modulus (G*) and phase angle (δ). A significant improvement is shown in rheological properties of the binder. Both modified bitumen are compared with a commercial SBS modified bitumen (Styrelf). However, stability remains an unsolved problem where further experimental analysis is to be done on these waste polymers. Investing in research on these material will help minimizing waste landfills and solve major environmental problems. Finally, considerable effect of using these modifiers on improving the original bitumen properties along with environmental and economical advantages, stimulated using these additive as an effective modifier.