Theoretical and Experimental Investigation into the Adhesion between Fiber-Reinforced Bitumen and Aggregates by Using Pull-out Method

1 Using fibers to reinforce bitumen is relatively a new method to improve mechanical properties of asphaltconcrete (AC). Economical competitive advantages, ease of use and improvement of physical and mechanical properties are the benefits of reinforcing AC with fibers in comparison with other modifiers, e.g. polymers. This paper investigates the adhesion of aggregates to fiber-reinforced bitumen. This concept has been described in two parts including theoretical and experimental sections. In the former section, pull-out force of aggregate through fiber-reinforced bitumen has been modeled by using "force-equilibrium method" and "slippage theory of short fiber composites". Therefore, the adhesion force between aggregate and fiber-reinforced bitumen was obtained based on fiber parameters. In the later section, polypropylene (PP) and polyester (PET) fibers of 12 mm length, at fiber content of 0.1%, 0.2% and 0.4% were used to reinforce bitumen. Both of lime and quartz aggregates were considered in the experimental design. Consequently, the Instron tensile tester was modified to perform pull-out tests. Pull-out test measured the force required to pull-out the aggregate through the bitumen and/or fiber-reinforced bitumen. The experimental results showed that the proposed model could predict the pull-out force of fiber-reinforced bitumen samples.