soundness test

1. Soundness Test of
Aggregates
 This test is used to determine
the resistance of aggregates to
disintegrate by saturated
solutions of sodium sulphate
or magnesium sulphate.
 This Test is easy but time
consuming.
Introduction:

2. Objective:
 To determine the
weathering action
of aggregates.

3. Apparatus & Materials Required:
 Sample container
 Weighing
machine
 Drying oven
 Immersion tank
 Coarse Aggregates
 Sodium
Sulphate(Na2So4)
Salt MgSo4 Na2So4
Anhydrous 350 gm 215 gm
Crystalline 1400 gm 700 gm
Minimum Mass of Salt Per Liter of Water

4. Fig: Sample Container,
magnesium sulphate and
sodium sulphate

5. Fig: Sodium Sulphate Fig: Sample Container

6. Procedure:
 1 kg of Coarse aggregates is taken as
sample.
 Sample is immersed in the
sodium sulphate solution for 24
hours.
 It is taken out from solution then, dried in
oven and cooled.
 Immersion, drying and cooling process is
repeated for 10 complete cycles.
 Finally retained weight on sample

7. Observation & Calculation:
Percentage loss = *100 %
W0-W1
W0
Where, w0 = initial wt of sample
w1= final retained wt on sample
container after 10 cycles
For example:
Let w0=100 gm
w1= 82 gm
Then, percentage loss = [(100-82)/100] *100 %
= 18 % which is less than 25%

8. Table of soundness test of aggregate

9. Discussion & Conclusion:
Since no. of cycles is 10 and re-agent
used is Na2So4 so the maximum
percentage loss is 25%.
When the percentage loss is greater
than 25% then, this test shows that
aggregate undergoes weathering process
which ultimately decreases bearing
strength. Hence, such aggregates cannot
be used in road pavement.
Aggregate having percentage loss less
than 25% is used in road pavement.