Relation of mechanical properties of recycled aged CRM mixtures with binder molecular size distribution

This paper presents an experimental analysis of the relationship between molecular sizes of mixed rubberized binders (aged rubberized binders + virgin rubberized binders) and the engineering properties of recycled aged rubberized mixtures. Gel permeation chromatography (GPC) was utilized to characterize the molecular size change of rubberized binders depending on three aging levels and four long-term aged (LTA) binder percentages. Rubberized mixtures were artificially long-term aged in the laboratory, and the aged rubberized mixtures were recycled at 0%, 15%, 25%, and 35% (by weight of total mixture) using typical recycling guildelines. Samples of laboratory-prepared recycled aged rubberized mixtures were tested for indirect tensile strength (ITS) in dry and wet states, rutting resistance, resilient modulus, and ITS after long-term aging in the laboratory. In general, the results indicated that the compositional changes of mixed rubberized binders have good correlations with the engineering properties of recycled aged rubberized mixtures, except for the resilient modulus.