Aggregate Impact Value Test
Aggregate Impact Value Test
Aggregate Impact Value Test
Aggregates play an important role in the design and construction of highway and air-field
pavements. They are also major part of rigid (concrete) and flexible (asphalt) pavements.
Aggregates is a combination of sand, gravel, crushed aggregates or other materials of mineral
composition. Aggregates used in road construction should be strong enough to resist crushong
and abrasion action under traffic wheel loads. If the aggregate is weak, the stability of
pavement structure is likely to be adversely affected.
Toughness is the property of material to resist impact. Due to traffic loads, the road
aggreagates is subjected to the pounding action or impact and there is a possibility of
aggregates breaking into smaller pieces. The road aggregates should therefore be tough
enough to resist fracture under sudden impact and moving loads.
OBJECTIVE
1. To determine the aggregates impact value (AIV) of aggregates road stone which is the
strength value of the aggregates.
APPARATUS
1. Aggregates
2. Test sieve
3. Small steel cylinder
4. Tamping rod
5. Mould
6. Impact testing machine
PROCEDURE
1. The aggregates was prepared by sieveing it firstly and the portion passing 14.0 mm
test sieve and retained on the 10.0 mm test sieve was obtained.
2. Then, the aggregates was washed and dried in the laboratory oven at a constant
temperature of 100 to 110℃ for not more than 4 hours. The aggregates then was
cooled to room temperature prior to test.
3. The aggregates was hit into smaller steel cylinder in three layers. Each of aggregates
layer was tamped 25 times using tamping rod. The tamping rod was adjusted to fall
freely from about 50 mm above the aggregate surface and it must be well uniformly
spread over. The surface was levelled with the tamping rod as a straight edge to
prepare the sufficient amount of aggregate on the top layer.
4. The aggregates was put into the bigger mould and 25 times tapping was applied for
each layer.
5. The cylinder was weighed plus the aggregates the weight data was recorded. (weight
A)
6. The sample was assembled in the apparatus and the hammer was released to fall freely
on the aggregates from a fixed vertical height of 380 ± 5 mm. The sample was then
subjected to a total of manual-controlled 15 blows.
7. The aggregates sample tested was removed from the mould and sieved through 2.36
mm test sieve.
8. The aggregates passing the 2.36 mm test sieve was weighed. (Weight B)
9. The test was repeated twice for the same batch of the aggregates sample.
RESULT
CALCULATION
Aggregate impact value (AIV) = (weight passing sieve) / (initial weight ) *100
(80/298)*100 = 26.8%
DISCUSSION
The aggregate impact value test is to determine the aggregate impact value (AIV) of
aggregate and to assess their suitability in road construction on the basis of impact value.
RECOMMENDED VALUES
10 – 20% Strong
In this test, we know the percentage of wear for the aggregate used in the test. The
percentage of wear vary between 10 % to 45% . We got the percentage of wear of the
aggregate is 26.8%. So, it is show that the aggregate had the average strength and had an
average resistivity against the abrasion and it is suitable for road surfacing.
CONCLUSION
In conclusion, the percentage of aggregate’s wear depends on the quality of aggregate.
In this test, we can conclude that the loss of aggregate is 1g and the percentage of wear is
26.8%. Lower abrasion loss values indicate the aggregate was tougher and more resistant to
abrasion.
1. Use hand gloves while removing containers from oven after switchin off the oven.
2. Special care should be taken that no outer air enters when using the balance.