Aggregate Crushing value test procedure of Coarse aggregate is required to find out the relative measure of resistance of an coarse aggregate crushing under gradually applied compressive load. We described the procedure of crushing value of aggregate test as per IS Code with Crushing value apparatus and Limits.
Aggregate Crushing Value Test Procedure
What is Aggregate Crushing Value?
Crushing value of aggregate is the resistance strength after applying a fixed load.
Why is Aggregate Crushing Value Required?
- Aggregate Crushing Value test required to know the resistance strength of coarse aggregate.
- Aggregate Crushing Value must be satisfied with resistance to crushing under the roller during compaction.
- If the aggregate are weak in resistance, the stability of the pavement or structure is likely to be adversely affected. So that the Crushing value of coarse aggregate is required.
Aggregate Crushing Value Test IS Code
IS Code for this test is IS 2386 part 3.
Aggregate Crushing Value Test Apparatus and Tools
- One metal cylinder for test and open on both ends ( dia – 152 mm, height – 130 mm to 140 mm ).
- Plunger ( dia – 150 mm ).
- Base plate ( thickness – 6.3 mm, square of 200 mm to 230 mm ).
- Tamping rod ( dia – 16 mm, length – 450 mm to 600 mm ).
- Weighing balance ( capacity minimum – 3000 gram, least count – 1 gram ).
- Compression testing machine.
- One cylinder for measure the sample for test ( dia – 115 mm, height – 180 mm ).
- IS Sieve 12.5 mm, 10.0 mm and 2.36 mm.
Precautions of Proceeding the Test
We should test the crushing value of aggregate in surface saturated dry condition.
If you are using oven-dried aggregates for this test, it shall be dried not more than four hours otherwise crushing value may affect.
Before Crushing Value test we should ensure that the aggregate’s temperature is similar to room temperature.
Crushing value apparatus and tools should be cleaned before proceeding the test.
Aggregate Crushing Value Test Procedure Step by Step
- Take aggregates for crushing value test from stacking yard not less than four places.
- Mix the aggregates and take the aggregate sample by quartering it.
- Near about 7 kilogram sample required for two tests.
- Sieve these aggregates through 12.5 mm and 10.0 mm.
- Take aggregates for the test which passed through 12.5 mm and retained on 10.0 mm.
- Take aggregate measuring cylinder and we have to pour aggregates in this cylinder in three approximately equal layers. Each layer shall be temped 25 times by tamping rod.
- In third layer fill aggregate over than the top surface of measuring cylinder then temp 25 times.
- Struck off the extra aggregates with temping rod using as a straight edge.
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- Take the weight of these aggregates, Note down as weight A.
- Place cylinder ( open on both end ) on the base plate then place weighed aggregates in this cylinder layer by layer.
- Again same procedure we have to follow to fill these aggregates in this open ended cylinder means three layers, 25 blows for each layer.
- Level the aggregates horizontally in the cylinder so that plunger can give the load all over aggregates.
- Place the plunger in the cylinder.
- Place this setup in compression testing machine, position in center.
- Set the rate of loading on 40 KN per minute so that it will reach 400 KN in 10 minutes.
- Stop the compression testing machine when it reaches 400 KN in 10 minutes.
- Place all aggregates and particles in 2.36 mm sieve which kept already in a tray.
- Sieve it until aggregate particles are passing. When it stops take the weight of passing material as weight B.
Aggregate Crushing Value Test Results, Calculation and Formula
Aggregate crushing value (%) = (B / A) *100
Aggregate Crushing Value Test Lab Report
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Aggregate Crushing Value Test Limit
Crushing Value Limit for
|Water bound macadam||40|
|Water mix macadam||40|
|Dense bituminous macadam||30|
|Concrete wearing Surface||30|
Aggregate Crushing Value Test Viva Questions
Q.1 What is aggregate crushing value?
Ans. Aggregate crushing value of an aggregate is the resistance strength of that aggregate after applying a fixed standard load.
Q.2 What is the IS code for the aggregate crushing test?
Ans. IS 2386 part 3 is used for the aggregate crushing test procedure.
Q.3 What sieves are required for crushing value test?
Ans. These sieves are required for crushing value test.
Q.4 What is the maximum limit of aggregate crushing value for bituminous concrete?
Ans. Limit of aggregate crushing value for bituminous concrete is maximum 30.
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