1how often do the pycnometers need to be calibrated?
daily
2the sample's moisture content needs to be less than what %?
0.1%
3what must be done to figure out moisture content?
AASHTO T329 or oven drying til constant mass
4what must you do when ANY coarse agg fraction has absorption > 2%?
a dry-back test
5how do you obtain the "dry back" A2 value?
by drying out your rice in front of a fan until constant mass (<0.05% change) in 15 min intervals
6where do you place the dry back weight (A2) in the Gmm equation?
replace A in the denominator (bottom) of the equation, keep the original A on top
7what is the first step when running a rice test?
separating the fines of the sample while cooling
8what must you keep in mind while separating the rice?
1. don't break the aggregate
2. reduce clumps to <= 0.25"
9when is rice separation finished?
when it has cooled to room temp
10what weights must you collect after separating the rice?
the pyc weight, pyc + sample weight
using these 2 weights you can get your dry sample weight (A)
11how deep does the water need to be?
1" above the sample's tallest point
12what is the vacuum spec for a rice test?
30 +- 5 mm Hg while agitating
13how long does the sample get vacuumed & agitated for in the pyc?
15 +- 1 min
14after the sample has been vacuumed
at what rate must you not exceed when releasing the vacuum?
release at a rate less than 60 mm Hg / sec
15what confirmations do you need to check before putting the vacuumed sample into the bath?
1. water temp is within spec (77 +- 2F)
2. water is at regular level
3. scale is tared
16what must you remove from the surface of the water in the pyc following the vacuum?
fines, can be removed by agitation or by alcohol
17what must you be careful not to do while transporting your rice sample to the bath?
exposing it to air (tilting it too much)
18how long do you need to keep the sample + pyc in the bath for?
10 +- 1 min
19after 10 minutes in the bath, what must be done?
record the pyc + sample weight, this is C in the Gmm equation
20how do you find B in the Gmm equation?
after 10 min in the bath remove all sample and reweigh
Underwater pyc mass = B