Properties of bituminous mixtures at low temperatures and relations with binder characteristics

Within the framework of a partnership between the "Departement Genie Civil et B (a) over cap timent" of the ENTPE, Eurovia and Appia, a research work including a large experimental campaign on the thermomechanical behavior of bituminous materials at low temperatures is proposed. The aim is to establish the links between the characteristics of the binder and the properties of bituminous mixes at low temperatures. Four different bitumens have been used with one type of aggregate and grading. The low temperature behavior of binders was evaluated with three fundamental tests: the complex modulus determination, the Bending Beam Rheometer and the tensile strength at a constant strain rate and constant temperatures. The thermomechanical behavior of bituminous mixes has been studied by performing complex modulus tests, measurements of the coefficient of thermal dilatation and contraction, tensile tests at constant temperatures and strain rates, and Thermal Stress Restrained Specimen Tests. The results are analyzed considering a rational approach. Some pertinent links between binders and mixes properties are established. Characteristics which are pertinent and discriminating enough with regard to the thermal cracking of bituminous mixes at low temperatures are presented. (c) 2004 RILEM. All rights reserved.