Figure 15-33.-Data sheet for specific gravity test.
6. Attach a vacuum pump to the flask and
an alternative to the
exhaust all air. The exhausted air is indicated
may be exhausted by
by rising bubbles. For most soils, 30 min
pension for
of pumping is enough. A heavy clay, however,
removal of
may require as much as 2 hr of pumping. As
the flask. A
15-27
vacuum pump, the air
gently boiling the
at least 10 min. To aid in
entrapped air, occasionally
slow boil should be used, as
sus-
the
roll
fast
