Behavior of Natural Fiber in Stone Matrix Asphalt Mixtures Using Two Design Methods

Abstract

The technology of asphalt materials and mixtures has evolved in the last four decades in Europe and North America. For the surface layer, there has been an increase in the use of more resistant and durable asphalt mixtures, such as mixtures with discontinuous graduation, e.g., stone matrix asphalt (SMA),which is a gap graded mixture containing 70–80% coarse aggregate of total aggregate mass, 6–7% of binder, 8–12% of filler, and about 0.3–0.5% of fiber. The fibers hold the binder in the mixture at high temperature and prevent drainage during production, transportation, and construction. This research presents a study of the behavior of natural fibers (coconut and cellulose fibers) on SMA mixtures using two different design methods (Marshall and Superpave). The specimens were tested using several common laboratory test procedures: draindown test, indirect tensile strength, resilient modulus, fatigue life, and moisture susceptibility. The draindown test results clearly revealed that coconut fiber can be used in SMA mixtures as a replacement for cellulose fiber to prevent asphalt draindown during production. This study intends to contribute to the development of new technologies suited for the needs of the local paving industry.