Influence of natural fibers on fracture strength of WMA (warm mix asphalt) concretes using a new fracture test specimen

Abstract

In this paper, two natural fibers (i.e. kenaf and basalt) are dispersed into WMA (warm mix asphalt) concretes to study their effect on fracture strength. The WMA concretes are reinforced by different percentages (i.e. 0.1, 0.3 and 0.5%) of kenaf and basalt fibers. A new test specimen (i.e. the disc bend (DB) specimen) is used to perform the experiments under various loading modes (i.e. pure mode I, mixed mode I/II and pure mode II). Indeed, this specimen has a circular geometry containing an edge crack, and the load is applied by a three-point bend fixture. The results demonstrate that both the kenaf and basalt fibers improve fracture resistance of the WMA mixtures. Addition of 0.3% of the kenaf and basalt fibers to the WMA concrete exhibits the highest positive effect on the fracture strength. Furthermore, WMA mixtures containing kenaf fibers showed better performance than those containing basalt fibers when they were loaded under pure mode I or mode I dominant mixed mode I/II. Conversely, the fracture strength of WMA mixtures is more improved by basalt fibers than kenaf fibers when the specimens were loaded under pure mode II or mode II dominant mixed mode I/II.