Analysis of the mechanical behaviour of bituminous mixtures at low temperatures

Abstract

The assessment of the mechanical properties of bituminous mixtures at low and intermediate temperatures is of great interest because it is in this temperature range that cracking failure due to mechanisms associated with fatigue failure from repeated load applications, thermal stress fracture or a combination of both occurs. Both distresses are complex and difficult to simulate in laboratory, especially fatigue failure, which requires expensive and time-consuming equipment set-up. For this reason, these mechanisms are hardly considered in asphalt mix design.This paper describes two procedures for mix design and assessment developed at the Road Research Laboratory of the Technical University of Catalonia: Fénix and EBADE tests. Fénix is a Semi-Circular Single-Edge-Notched Tension (SENT) test while EBADE is a cyclic fatigue test on a prismatic specimen in Double-Edge-Notched Tension (DENT).The aim of this work is to analyze the ability of these tests to assess changes in the cracking resistance of binder-containing mixtures with test temperature. A “master curve” or curve of mixture property variation with temperature is drawn from test results to determine bituminous mix response, especially at low temperatures where cracking resistance is more critical.