The
rubber-modified liquid asphalt contains 10% minus 40-mesh rubber.
The
rubber-modified liquid is reacted for 15 minutes at 350° F.
SCDOT
Superpave Mix Design Procedures are Used
Aggregate
pans are batched in correct proportions along with hydrated lime
and heated to 50° F above compaction temperatures.
Rubber-modified
liquid asphalt is heated to mixing temperature and added to aggregate
batches in correct proportions for four different asphalt contents.
(ex. 5.0%, 5.5%, 6.0%, 6.5%)
Rubber-modified
liquid asphalt and aggregate batches are mixed with mechanical mixer
to form a homogeneous mixture.
Loose
mix batches are "cured" in the oven at compaction temperature
for 2 hours.
Loose
mix batches are dumped into molds using a funnel and temperature
is checked.
Samples
are compacted using Superpave gyratory compactor.
Volumetric
properties of compacted sample "pills" are measured (ex.:
air voids, VMA, and VFA) and optimum apshalt content is chosen.
Final
mix design specifies optimum proportions of "ingredients"
(lime, modified asphalt cement, coarse aggregate and fine aggregate)
to be used to make rubber-modified HMA at the contractor's plant.