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.