Question

What is the are the issues that void filled asphalt over its limit?

Answer 1

Percent Voids Filled with Asphalt (VFA)

The VFA is the percentage of voids in the compacted aggregate mass that are filled
with asphalt cement. It is synonymous with the asphalt-void ratio. The VFA
property is important not only as a measure of relative durability, but also because
there is an excellent correlation between it and percent density. If the VFA is too
low, there is not enough asphalt to provide durability and too over then it get densify under
traffic and bleed. Also the VFA controls the air void in the mix design which is very critical, higher the VFA lower will be the air voids.
The durability of an asphalt pavement is a function of the air void content.
Too high an air void content provides passageways through the asphalt
mixture for the entrance of damaging air and water. Too low an air void
content, on the other hand, may lead to flushing, a condition where excess
binder squeezes out of the asphalt mixture to the surface.
Density and air void content are directly related. The higher the density, the
lower the percentage of air voids in the asphalt mixture. Specifications
require pavement densities that produce the proper amount of air voids in the