Correlation of Binder GPC Characteristics and Mechanical Properties of Hot-Mix Recycled Asphalt Mixtures

This study examined the correlation between mechanical properties and LMS(Large molecular size) of binders in hot-recycled asphalt mixtures. Hot-recycled asphalt mixtures were manufactured by various mixing methods. Laboratory tests including indirect tensile strength, wheel tracking test and Kim test were performed for each recycled mixture. Gel-permeation chromatography (GPC) analysis was performed for the binders coated on virgin and old (RAP) aggregates separately. For the purpose of binder aging analysis, a round-shaped virgin coarse aggregates (13mm gravel) were introduced in recycled mixtures. This makes possible to distinguish the virgin aggregates from RAP aggregates in recycled mixtures for GPC sampling. Results of GPC showed that there was significant difference in aging level between the binder coated on RAP and that of virgin aggregates in the same recycled mixture. Regression analysis was performed to correlate mechanical properties to LMS ratio. Results showed that most of the mechanical properties had relatively good correlation with LMS. This trend agree with LMS increase up to some degree, but fails for further LMS increase.