InstroTek
18
7. Maximum Specific Gravity (G
mm
) of Loose Asphalt
Mixtures ASTM D6857
The following procedure can be used as an alternative to “Rice” Test AASHTO
T209 and ASTM D2041 for determination of maximum specific gravity of loose
asphalt mixtures. This procedure requires that a sample of dry asphalt mixture
be placed inside two bags and vacuum-sealed with the CoreLok. The bags are
then cut open underwater and a submerged weight is determined. The weight
in air and the submerged weight can be used to calculate the maximum
specific gravity of the asphalt mixture.
Note: The latest version of the GravitySuite
software can be downloaded from
our web site at www.Instrotek.com/downloads.
Important: To avoid errors in submerged weight of the sample, use a large water
tank. The minimum recommended dimensions for the tank are 610(L) X460(W)
X460(D) mm (24X18X18 in).
Caution: Accurate sampling is crucial in obtaining repeatable results. Please
take care when selecting test samples.
Note: Make certain the sample is at room temperature before beginning the
test.
Procedure
1.
Set the CoreLok machine to Program #2. In Program #2, the Dwell time is set
at 300 seconds, thus making sure that all trapped air is removed out of the
bags.
2.
Place all three filler plates inside the CoreLok. You do not need the sliding
plate for this test
3.
Select a large bag. Inspect the bag for holes or stress points. Do not use the
bag if you find holes or stress points.
4.
Weigh the large bag and one channel bag (the clear bag with one textured
side). Record the total weight in column A of the Max/Apparent Gravity
Data Collection Table
(pg. 25).
5.
Weigh the dry sample and record the sample weight in column B. You may
use up to 2000 grams of loose mixture per test.
6.
Place the sample inside the channel bag.
7.
Place the empty large bag (external bag) inside the CoreLok chamber.
