Changes in properties of bitumen in surface layers of rolled-asphalt wearing-courses -- 1, 2: Fid-Bau Portal

Changes in properties of bitumen in surface layers of rolled-asphalt wearing-courses -- 1, 2

Please, A. / Mayer, F.E. / Tingle, E.D. / Green, E.H.

Pt 1. Dependence of surface texture of asphalt on type of bitumen; binders from 10 different crude sources were used in experiments; it was found that for majority of binders, provided sufficient binder is used, rolled-asphalt surfacings are very durable but that very different surface textures and resistances to skidding were developed by surfacings; performances of materials are traced to susceptibility of constituent binders to harden by weathering, to be fluxed with lubricating oil dropped by vehicles, and to resist leaching action of water. Pt 2. Changes in bitumen composition causing changes in viscosity; examination was made of experimental surfacings laid on heavily trafficked road which comprised asphaltic concrete sections using refinery bitumen and fluxed Trinidad lake asphalt as binders, and rolled asphalt sections using refinery bitumens from two distinct crude sources; changes in viscosity were determined for bitumen recovered from upper-most layer of experimental surfacings and in successive 0.5-mm layers of rolled asphalt sections; solvent fractionation technique.