A comparative analysis of modified binders : original asphalts and materials extracted from existing pavements : tech summary.

Tech summary.PDFBooklet/PamphletLTRC Report 462LTRC Project Number: 04-3BState Project Number: 736-99-1498Asphalt pavementsPavementsBindersChromatographyGel permeation chromatographyLouisianaLouisiana Transportation Research CenterDaly, WilliamLouisiana Transportation Research CenterLouisiana. Dept. of Transportation and DevelopmentNTL-HIGHWAY/ROAD TRANSPORTATION-MaterialsNTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and PerformanceUS Transportation CollectionDuring oxidative aging, polar and aromatic molecules interact through attractive forces to form molecular associations resultingin signifi cant changes in the physical properties of asphalts. One consequence is that these associations have eff ective molecularweights and hydrodynamic volumes larger than the true molecular weights of their components. A separation of the components ispossible using gel permeation chromatography (GPC), which is also a fast and reliable method to determine the polymer content inasphalt. Since polymer molecules typically exhibit molecular weights 100 times greater than those of asphalt molecules, they can beeasily identifi ed using this method. GPC methodology was applied to follow the processing and paving sequences and to determinethe changes in the mix during its lifetime. The research involved quantitatively assessing (1) the amount of the polymeric speciesin a polymer modifi ed asphalt cement (PMAC) as received from a supplier, including changes imparted by the addition of recycledasphalt pavement (RAP) to the mix; (2) the amount of the polymeric modifi er in the liquid extracted from cores taken from a new roadpaved with the same PMAC as that received from a supplier; and (3) the extent of on-the-road degradation of the polymeric speciesby oxidative aging for periods up to 20 months. The research was extended to evaluate mixescontaining a crumb rubber modifi er (CRM), which is practically insoluble in GPC solvents