WATER ABSORPTION TEST OF AGGREGATE
OBJECTIVE
For determination of water absorption of aggregates.
REFERENCE STANDARDS
IS : 2386 (Part 3) – 1963 – Method
of test for aggregates for concrete (Part I) Particle size and shape.
EQUIPMENT & APPARATUS
§ Wire basket
§ Oven (3000c)
§ Container for filling water and suspending the basket
§ An air tight container
§ Balance[0-10 kg]
§ Shallow tray & absorbent clothes.
PREPARATION OF SAMPLE
The sample to be tested is separated
from the bulk by quartering or by using sample divider.
PROCEDURE
1.
About 2kg of the aggregate sample
is washed thoroughly to remove fines, drained and then placed in the wire
basket and immersed in distilled water at a temperature between 22 to 320C
with a cover of at least 50 mm of water above the top of the basket
2.
Immediately after the immersion the
entrapped air is removed from the sample by lifting the basket containing it 25
mm above the base of the tank and allowing it to drop 25 times at the rate of
about one drop per second. The basket and the aggregate should remain
completely immersed in water for a period of 24±0.5 hours afterwards.
3.
The basket and the sample are then
weighed while suspended in water at a temperature of 22 to 320C. The
weight is noted while suspended in water (W1) g.
4.
The basket and the aggregate are
then removed from water and allowed to drain for a few minutes, after which the
aggregates are transferred to one of the dry absorbent clothes.
5.
The empty basket is then returned to
the tank of water, jolted 25 times and weights in water (W2) g.
6.
The aggregates placed in the dry absorbent
clothes are surface dried till no further moisture could be removed by this
clothe.
7.
Then the aggregate is transferred to
the second dry cloth spread in a single layer, covered and allowed to dry for
at least 10 minutes until the aggregates are completely surface dry. 10 to 60
minutes drying may be needed. The surface dried aggregate is then weighed W3 g.
8.
The aggregate is placed in a shallow
tray and kept in an oven maintained at a temperature of 1100C for 24
hours. It is then removed from the oven, cooled in air tight container and
weighed W4 g.
Table :-Observation table for Water
Absorption
S.No.
|
Dry wt
in gm
|
Wt water
in gm
|
Water
absorb.
|
W.A. %
|
Avg. %
|
1
|
1886
|
1987
|
101
|
5.36
|
|
2
|
1886
|
1978
|
92
|
4.87
|
5.19
|
3
|
1886
|
1986
|
100
|
5.35
|
|
CALCULATION
Weight of saturated aggregate
suspended in water with basket = W1 g
Weight of basket suspended in water
= W2 g
Weight of saturated aggregate in
water = (W1-W2)g = Ws g
Weight of saturated surface dry
aggregate in air = W4 g
Weight of water equal to the volume
of the aggregate = (W3-Ws) g
PRECAUTIONS
§ Use hand gloves while removing containers from oven after
switching off the oven.
§ Thoroughly clean & dry the container before testing.
§ Special care should be taken that no outer air enters when
using the balance.
§ Use apron & safety shoes at the time of testing.
§ All parts of the equipment should always be kept
clean.
No comments:
Post a Comment