Dynamic Properties of Fiber-Modified Overlay Mixture

Abstract

Cores and slabs of fiber-modified asphalt overlay were taken from a series of test sections constructed on two highways in Indiana. Extensive laboratory investigations were conducted to evaluate the fiber-modified asphalt mixtures. Laboratory tests included physical properties, beam fatigue, and complex modulus. Because of a lack of a standard method for fiber extraction, three fiber extraction methods were evaluated. Test results show that more than 95 percent of fiber can be extracted from paving mixtures. Actual fiber contents in test sections were found to be different from target fiber contents by a significant amount. Physical property tests show that the addition of fibers is related to a higher percentage of air voids in the in situ pavement. Results of fatigue tests indicate that fibers increase the fatigue life of overlay mixture. There are inconsistencies in the significance of fiber on both dynamic modulus and phase angle. However, the results do indicate that the addition of fibers will change the viscoelastic properties of mixtures. There is no statistical difference in dynamic modulus and phase angle among the mixtures with different fiber contents.