Fiber reinforced asphalt

Asphalt can be considered a particulate composite with almost no tensile strength, that is, the only physical link between the matrix (bitumen) and the particles (gravel) is the cohesive strength of the bond itself and the aggregate simply breaks away from the binder under any number of tension-based loads such as earth shifts, heavy loads, and even moisture. Over the course of a few months, these breaks lead to larger cracks, potholes, and damaged entire road sections that require significant investment much earlier than the expected 15-year lifecycle. Increasing the strength and modulus of asphalt can improve its durability, extend its lifespan, and reduce its maintenance costs. However, as most asphalt is usually recycled during rehabilitation, improving strength cannot come at the expense of the existing infrastructure support system, i.e., materials and technologies should be compatible with road resurfacing equipment and practices. Short composite fibers have high modulus and strength but are easily broken up by road milling machines, making them ideal candidates to mix into the asphalt during rehabilitation. Additionally, by deliberately limiting the fiber size, this will have a major ancillary benefit for the environment: allowing the use of off-fall composite scraps from the manufacturing sectors that are often chopped and relegated to landfills. This investigation examines the material behavior from both experimental and numerical perspective on the inclusion of short fibers for reinforcing asphalt, creating a dual fiber and particle composite material system. Asphalt by its very nature is a relatively soft material with high strains until failure under some conditions, and brittle under others, making this a complex material system combining both hyperelastic and elastic-brittle response. Validation studies are examined for this unique material under various quasi-static to dynamic loading rates to create a material system for extended finite element analysis in improved infrastructure designs.