Effectiveness of a Pullout Test Method Developed to Characterize Fundamental Fiber-Matrix Interfacial Mechanisms in Viscoelastic Asphalt Concrete

Abstract

Current production of fiber-reinforced asphalt concrete (FRAC) is associated with challenges related to performance inconsistencies, workability, and economic feasibility. Understanding fundamentals of fiber-matrix interaction in FRAC is key to identifying root causes of the observed inconsistencies and enhancing the performance of FRAC mixtures. There is no model or experimental method to predict fiber behaviors in viscoelastic AC. A novel fiber pullout test procedure was designed and developed to characterize interfacial properties of fibers in a viscoelastic AC medium. The test method was used to develop a fundamental understanding of fiber pullout behavior where fiber diameter, embedment length, and mixture characteristics are considered as key test parameters. The test method allowed characterization of the effects of temperature and loading rate as well considering fiber reinforcement in viscoelastic AC application. The pullout tests were successfully completed for the key variables. The experiments were extended to mixture scale to apply some of these key fundamental principles learned from the pullout tests. Embedment length and fiber diameter emerged as the key variables of pullout behavior of fibers in the AC. The fiber-matrix interface was not found to be sensitive to temperature and loading rate as much as bulk viscoelastic AC is. The proposed testing method designed and developed in this paper will help in building fundamental constitutive relationships of fiber-matrix behavior in viscoelastic AC and design FRAC mixes using a mechanistic approach.