Laboratory and field performance investigation of pre-swollen crumb rubber modified asphalt mixtures

Abstract

The pre-swollen crumb rubber (PSCR) is a pelletized rubber produced by the reaction of scrap tire rubber particles with bitumen -compatible oil at elevated temperatures. It does not require a prior blending with bitumen, and it can be added directly at an asphalt plant. A laboratory investigation was carried out to evaluate the performance of plant-produced PSCR modified mixtures for surface and intermediate courses and analyze their suitability for low-traffic volume road in cold environment applications. Linear viscoelastic properties, rutting and thermal cracking performance were investigated in the laboratory. The presence of pre-swollen rubber particles and, in particular, the bitumen-compatible oil softened the mixtures as indicated by the dynamic modulus master curves. The different mechanical responses led to an enhancement of thermal cracking resistance but increased the rutting susceptibility of the PSCR mixtures. Despite the laboratory findings, no rutting was observed after five years of service life based on visual inspection of the field test sections constructed in Michigan with PSCR-modified Hot-Mix Asphalt (HMA). A few transverse cracks were generated in the lanes where the control mix with neat bitumen was used. Those cracks did not propagate into the PSCR modified material, in agreement with the laboratory findi ngs.

Life Cycle Risk Assessment Applied to Gaseous Emissions from Crumb Rubber Asphalt Pavement Construction

“…Besides the standard hot mixtures composed of aggregates and asphalt binder, several other types of asphalt mixtures have been developed. Asphalt mixtures modified with synthetic or recycled polymers (e.g., styrene-butadiene-styrene, crumb rubber from end-of-life tires) are widely used and have better mechanical performance than standard mixes [2][3][4][5][6][7][8][9][10][11].…”

Effect of Waste Polyethylene and Wax-Based Additives on Bitumen Performance

“…The simultaneous addition of polymers and viscosity reducers is considered a suitable solution to improve the workability of modified binders, and it is currently under investigation. Nonetheless, with very few exceptions, this methodology has been only tested with the classic and most common polymeric modifiers, such as SBS [2,6,[20][21][22][23][24] and crumb rubber [22,[25][26][27][28][29][30][31][32][33]. Thus, intensive research is required to evaluate their effects on more innovative composites.…”