Master of Science (MS)
Blends of a PG 64-22 asphalt with a range of load levels (0.2 — 20 wt %) of Sasobit® wax and a single loading of 2 wt % Elvaloy AM® were prepared and characterized. Sasobit® wax is a high molecular weight paraffinic wax produced commercially through the Fischer-Tropsch process. Elvaloy AM® is a reactive elastic terpolymer, comprised of ethylene, butyl acrylate and glycidyl methacrylate monomeric units. The blends were analyzed by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), x-ray diffraction, epifluorescence microscopy, scanning laser confocal microscopy, and dynamic shear rheology. Sasobit (1 wt %) composite material showed little difference in aging characteristics with respect to the aging chromatograms of the un-modified asphalt cement. Aging of Elvaloy (2 wt %) composite material leads to increased concentrations of asphaltene and asphaltene aggregate components at a greater rate than that observed with the Sasobit composites and unmodified asphalt cement. Analysis of DSC heating curve enthalpies revealed that Sasobit composites at loadings above 4% that the Sasobit was completely crystalline. X-ray diffraction confirmed that ambient temperature Sasobit composite samples maintained their crystalline form down to the level of 0.2 wt % loading. Evidence for the additives presence could be seen within the asphalt matrix through epifluorescence and scanning laser confocal microscopy imaging of each of the composite systems investigated. Bright point-sources of fluorescence, most easily picked out in the Elvaloy (2 wt %) composite images, are believed to be asphaltene micelles. Evidence of improved G* performance in both Sasobit and Elvaloy composite master curves with respect to the neat asphalt cement master curves is presented. The dynamic viscosity data at 1 Hz shows that original and TFOT data doesn’t clearly differentiate between Sasobit composites and neat asphalt cement until after PAV aging. At that stage the Sasobit composite shows truly linear dynamic viscosity response suggesting that Sasobit inclusion leads to better dispersion of the viscosity building asphaltene component throughout the asphalt cement. It is believed that the Elvaloy AM composite experienced some degree of crosslinking during aging and this is most evident following the PAV aging in the rheological data.
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Sellers, Brent Harper, "Characterization and transitions of asphalt cement composite materials" (2009). LSU Master's Theses. 2063.
William H. Daly