Description
Binder-aggregate adhesion is a property of critical importance with regards to pavement durability. As such transportation agencies often have specific requirements with regards to aggregate-binder adhesion. In many Nordic countries a suite of specifications have been developed to evaluate the adhesive properties of various modifiers. Due to the limited use of crumb rubber modified binders in Nordic countries, little data is available with regards to how asphalt rubber and other crumb rubber modified binders fare when evaluated using these test methods. While asphalt rubber is known to decrease rutting and increase pavement flexibility, to date few studies exist which evaluate how the addition of crumb rubber may affect adhesion between aggregate and binder.
The purpose of this investigation was to evaluate how crumb rubber modification of binders affects aggregate-binder adhesion when evaluated using the rolling bottle test method. Specifically, the investigation will establish how binder-aggregate adhesion of crumb rubber modified binders varies depending on the type of anti strip additive (hydrated lime and amine) used.
Binder-aggregate adhesion was evaluated after time intervals of 6, 24, 48, and 120 hours to gain an idea of how stripping develops as a function of time in the rolling bottle evaluation. Testing involved the evaluation of a reference binder, a 10% CRM binder, and an asphalt rubber binder. A Norwegian aggregate with average quartz content was mixed with all the above mentioned binders, in addition samples were also prepared using 1.5% hydrated lime and 0.5% liquid ASA. Through this evaluation a comprehensive picture of how rubber modification affects aggregate-binder adhesion was obtained.
