Modifiers for Asphalt Concrete
Final rept. Sep 1987-Mar 1988
HARDING LAWSON ASSOCIATES NOVATO CA
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The primary objective of this research was to identify the most promising types of asphalt modifiers for reducing permanent deformation rutting in flexible airfield pavements. Modifiers selected for evaluation included carbon black, sulfur, styrene-butadiene-styrene, ethyl-vinyl-acetate, and polyolefin. A series of binder and mixture tests were performed in the laboratory to evaluate the modifiers effects on an AR-4000 asphalt cement, and an asphalt concrete mixture containing a subrounded river gravel. Binder tests were performed before and after aging in the rolling thin film oven, and included penetration, viscosity, and ductility. Mixture tests included Marshall stability and flow, resilient modulus, creep modulus, and indirect tension. The results were used to estimate the effects of the modifiers on pavement rutting. All of the modifiers significantly reduced the amount of rutting estimated for a thin and thick pavement in a hot climate.
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