Strength and ductility of asphalts

Abstract

This article presents data on the ductility of asphalt as measured in an RMI-5 tensile tester, which is designed for tests on raw and vulcanized rubbers and rubber mixes. The asphalt test specimens were prepared in the form of ''figure eights'' and the tests were performed at 23-24/sup 0/C. Discrete load levels were determined at each 25-50% elongation. The true stress was calculated on the basis of the actual cross section of the specimen at the point of measurement, which was determined from motion picture photography of the elongation process. The addition of finely dispersed limestone to the asphalt leads to a sharp increase of its structural strength and a reduction of its total elongation. The particles of finely dispersed powders are implanted between the aggregates of asphaltenes and resins, binding them into a rigid, relatively immobile system, making it more difficult for these aggregates to straighten out and become oriented in the continuous malthene phase in the direction of the axis of elongation, as reflected in the presented stress/ elongation diagram. It is determined that the addition of 1% SKDP-N rubber to the BND 40/60 asphalt leads to an increase in ductility while strength is maintained. Includes a table.