Permanent Deformation Characteristics of Warm Asphalt Binders under Reduced Aging Conditions

Abstract

Warm Mix Asphalt (WMA) technologies allow a 20 to 40°C reduction in production temperatures of asphalt mixes. These technologies are often synergistically combined with modified asphalt binders to tackle the increased production temperature requirements with these binders. Because of lower production temperatures, the asphalt binders containing WMA additives undergo reduced short-term aging and thus need to be examined for permanent deformation behavior at different reductions in production temperatures. The present study evaluates permanent deformation characteristics of warm asphalt binders as function of short-term aging temperature, modified binder type, and various dosages of a wax-based WMA additive: Sasobit. Experimental variables included are: three short-term aging temperatures (163°C, 143°C, and 123°C), two modified asphalt binders (polymer, and crumb rubber modified), and three contents of WMA additive (1%, 2%, and 3%). Warm binders as well as control binders are characterized in terms of viscosity, failure temperature, temperature sweep, frequency sweep, and multiple stress creep and recovery tests. WMA additive compensates the reduced stiffness of binders on being aged at lower temperatures, as rheological parameters of warm binders aged at 143°C and 123°C compare well with control binders. Statistical models for the rheological parameters as function of the experimental variables are also developed.