Aging Effect on Modified Bitumen
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Polymers are the most common modifiers currently being used to improve bitumen properties. The polymers increase the temperature range over which a binder resists both rutting and thermal cracking. In this paper VG10 bitumen and two polymers: Styrene Butadiene Styrene (SBS) block copolymer, Ethylene Vinyl Acetate (EVA) polymer and crumb rubber (CR) are used as modifiers with varying percentage of 2%, 5% and 8%. The SBS and EVA modified bitumen samples were prepared by means of high and low shear laboratory type mixer rotating at 3000 rpm and 1500 rpm, respectively at a temperature of 180oC whereas for the preparation of CR the modified samples are prepared at 1100 rpm. The ageing properties of polymer modified bitumen (PMB) have the main role in quality of PMB dispersions and solid PMB. For Short term aging the virgin bitumen and SBS/EVA and CR blends were aged by means of the Thin Film Oven Test (TFOT), at a temperature of 163oC for 5 hrs. The change in physical properties such as penetration, viscosity, softening point, elastic recovery and loss in weight were compared before and after short term ageing.
Keywords: TFOT, SBS, EVA, Brookfield viscometer