31 Dec 96
which resulted in a VTM value closest to 30.0 percent. If no VTM
averages are in the 30.0 percent range, then slight adjustments
to the aggregate gradation may need to be made to achieve the
proper void content. Optimum asphalt contents resulting in
average VTM values in the 25 to 35 percent range are acceptable,
but due to normal production and construction variations, a mix
design that provides a 30-percent VTM value is most desirable.
(Typical optimum asphalt contents are between 3.5 and 4.5
(1) The open-graded asphalt concrete job-mix formula will
consist of the following information:
Percentage of each aggregate stockpile.
(b) Percentage passing each sieve size for the blended
Percentage of bitumen.
Temperature of discharged asphalt mixture.
Voids total mix percentage.
(2) The target temperature of the asphalt mixture when it
is o ischarged from the mixing plant should be 125 + 5oC. Select
120 C when ambient temperatures are relatively high and the haul
distance from the asphalt plant to the job site is short. Select
125oC when either the haul distance is relatively long or the
ambient temperatures are relatively cool. Select 130oC when
ambient temperatures are expected to be cool and the haul
distance is relatively long. Persistent high winds during
construction may also require mix production temperatures to be
in the 125oC to 130oC range.
Resin Modified Portland Cement Grout.
(1) Gather representative samples of portland cement,
silica sand, Class F fly ash, and resin additive. Minimum sample
sizes are 23 kg each of cement, sand, and fly ash, and 4 L of
resin additive. Ensure that all materials meet the quality
requirements as detailed in CEGS-02548.