VTM = (1 - WTAIR /Volume * 1/SGT) * 100 VTM = [1 - WTAIR /Volume *
1/(SGT * 62.4lbs/CF)] * 100
where
WTAIR = dry weight of specimen in grams lbs
Volume =0.785(D)(H)
D = diameter in cm feet
H = height in cm feet
SGT = maximum theoretical specific gravity
(2) Calculate the average VTM for each of the five asphalt cement
contents. Select the optimum asphalt content as that which
resulted in a VTM value closest to 30.0 percent. If no VTM
averages are in the 30.0 percent range, then make adjustments to
the aggregate gradation 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, the JMF shall be based on a mix
design that provides a 28 to 32 percent VTM value is required.
Typical optimum asphalt contents are between 3.5 and 4.5 percent.
2.6.1.4
Job-Mix Formula Submittal
(1) The open-graded asphalt concrete job-mix formula will consist
of the following information:
(a)
Percentage of each aggregate stockpile.
(b)
Percentage passing each sieve size for the blended aggregate.
(c)
Percentage of bitumen.
(d)
Temperature of discharged asphalt mixture.
(e)
Voids total mix percentage.
(2) The target temperature of the asphalt mixture when it is
discharged from the mixing plant should be 125 5C 257 9F.
The contractor shall adjust the temperature depending on the
ambient temperatures and the haul distance from the asphalt plant
to the job site to meet the lay-down temperature.
2.6.2
Job Mix Formula for Slurry Grout
The Job-Mix Formula (JMF) for the slurry grout shall be furnished by the
Contractor and approved by the Government. The slurry grout job mix
formula shall be developed using the proportions given in Table V.
TABLE V
RESIN MODIFIED CEMENT SLURRY GROUT MIXTURE PROPORTIONS
Material
Percent by Weight
------------------------------------------------------------
Silica Sand
16-20
Fly Ash
16-20
Water
22-26
Portland Cement
34-40
Cross Polymer Resin
2.5-3.5
Approximately 12 to 15 kg 22 to 28 pounds of mixed slurry grout will fill
SECTION 02746
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