Implementation of GPC characterization of asphalt binders at Louisiana Materials Laboratory : research project capsule.

PDFTech Report10-6BAsphaltBindersLouisianaLouisiana Transportation Research CenterDaly, William H.Morvant, Mark J.Abadie, ChrisLouisiana Transportation Research CenterLouisiana. Dept. of Transportation and DevelopmentLouisiana State University (Baton Rouge, La.)NTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and PerformanceNTL-HIGHWAY/ROAD TRANSPORTATION-MaterialsNTL-HIGHWAY/ROAD TRANSPORTATION-Construction and MaintenanceUS Transportation CollectionLouisiana has been using polymer modified asphalt cement (PMAC) increasingly forbetter pavement performance. More often than not, elastomers became theasphalt modifiers of choice due to their excellent elasticity and good compatibilitywith asphalt species. A new analytical tool is needed for assessing the presenceand quantification of the amount of the elastomer modifier, both in a suppliedPMAC and in a liquid extracted from pavement cores. Due to a large differencebetween the molecular mass of polymer molecules and the mass of asphaltcomponents, the polymer can easily be visualized through a size exclusion analysis,such as gel permeation chromatography (GPC). GPC methodology can be applied toroutine characterization of asphalt binders and can employ the technique inforensic analysis of paving problems. It traces PMAC dissolved in tetrahydrofuran(THF) solution and styrene-butadiene-styrene (SBS) polymer dissolved in decalinsolution. The samples are injected into a set of porous columns and eluted withTHF. The order of elution is related to the molecular weight of the component. Highmolecular weight species elute first followed by molecules with ever decreasingmolecular weight. This study will evaluate the amount of the polymeric species in apolymer modified asphalt binder, the changes imparted by the addition of recycledasphalt pavement (RAP) to the mix, and mixes containing a crumb rubber modifier(CRM). Utilization of GPC to monitor the amount of the polymeric material in polymermodified asphalt binders could conceivably establish a better characterization ofasphalt materials