Sample for test.
A
sample of about 1 kg of the aggregate shall be used. Aggregates which have been
artificially heated shall not normally be used; if such material is used, the
fact shall be stated in the report. Two tests shall be made. The sample for
test shall be thoroughly washed on the test sieve to remove finer particles and
drained.
Test
procedure
Immerse
the prepared test sample In water in the glass vessel; it shall remain immersed
at a temperature of 20° C ± 5° C for 24 h ± 0.5 h. Soon after immersion and again at the end of soaking period,
remove air entrapped in, or bubbles on the surface of, the aggregate by gentle
agitation. This may be achieved by rapid clockwise and anti-clockwise rotation
of the vessel between the operator's hands.
Overfill
the vessel by adding water and slide the plane-ground glass disc over the mouth
so as to ensure that no air is trapped in the vessel. Then dry the vessel on
the outside and weight it (mass B).
The
empty the vessel and allow the aggregate to drain while the vessel is refilled
with water, sliding the glass disc into position as before. Then dry the vessel
on the outside and weigh it (mass C).
The
difference in the temperature of the water in the vessel during first and
second weighing shall not exceed 2° C.
Place
the aggregate on a dry cloth and gently surface-dry it with the cloth,
transferring it to a second dry cloth when the first will remove no further
moisture. Then spread it out not more than one step deep on the second cloth
and leave it exposed to the atmosphere away from direct sunlight or any other
source of heat until all visible films of water are removed but aggregate still
has a damp appearance. Weigh the aggregate (mass A) If the apparent particle
density only is required the operations described in this paragraph may be
omitted.
Place
the aggregate in the shallow tray in the oven at a temperature of 105° C ± 5° C for 24
h ± 0.5 h.
Then
cool it in the airtight container and weight it (mass D).If the particle
density on a saturated and surface-dried basis only is required, the operations
described in this paragraph may be omitted.
