Examination of Significant Binder Aging Due to the Use of Different Anti-Stripping Additives in Polymer and CRM Asphalt Mixtures Using GPC
Abstract
As an anti-stripping agent (ASA), hydrated lime (HL) has been widely used for many years in the world. Many brands of liquid-type ASA (LA), which properly provided the anti-stripping function, have been also developed and marketed. Because HL was found to provide anti-aging function of the binder in the mix, in addition to anti-stripping function, its use was known to have many advantages of other beneficial functions to the asphalt pavement. However, because the anti-aging function of LA is in question, it will be important to recognize if the anti-aging function is presented by the LAs too. Therefore, this study investigated the anti-aging effect of HL and three LAs in normal, crumb rubber–modified and polymer-modified asphalt mixes, in terms of absolute viscosity (AV) estimated from the large molecular size (LMS) measured by gel permeation chromatography (GPC), a scientific equipment. It was found that HL provided a significant retardation of age hardening, compared with the binder of the mix without any ASA. However, unlikely the anti-stripping function, most of the LAs did not show age retardation effect. The anti-aging function of liquid additives was not proved in this study, and therefore, the significant difference in binder aging was present due to the use of different ASA.