Aggregate impact test required to find out the physical strength of coarse aggregate. We described procedure of impact test on aggregate with a diagram as per is code on impact testing machine.
What is Aggregate Impact Test Value ( AIV)?
Aggregate impact value is the physical strength of any type of aggregate which is going to be used for any type of construction work like concrete, roadwork, flyover work, bituminous work, etc…
Aggregate impact value is an important mechanical property of coarse aggregate.
Why Aggregate Impact Value Test required ( AIV Test)?
Aggregate Impact value test is required to ensure the “physical strength of aggregate” and physical strength of aggregate directly related to structural strength in construction work.
Apparatus and Tools required for Aggregate impact value ( AIV ) test
- Aggregate Impact value test machine.
- Cylindrical steel cup which dia is 102 mm and depth is 50 mm.
- Cylindrical steel cup for measure the sample for the test which dia is 75 mm and depth is 50 mm.
- Metal hammer attached with impact value testing machine which weight shall be between 13.5 to 14.0 kg.
- IS sieves 12.5 mm, 10.0 mm and 2.36 mm.
- The tamping rod which dia is 10 mm, the length is 230 mm and rounded at one end.
- Weighing balance with 0.1 gram accuracy.
- Oven for temperature 100 to 110 centigrade.
Aggregate Impact Testing Machine Specification
Aggregate Impact Value Test ( AIV ) IS CODE
IS Code for Determination of Aggregate impact value ( AIV ) test is 2386 part 4.
Precautions Before Proceeding
- The impact value test machine and its components must be clean.
- Check the falling height of metal hammer in impact value testing machine. It Shall be 380 +/- 5 mm, which means 375 mm to 385 mm.
Determination of Aggregate Impact Test
- The procedure will start by sieving coarse aggregates passing through 12.5 mm and retained on 10.0 mm.
- Put this sieved material in Hot air oven for four hours in between 100 and 110-degree centigrade temperature.
- Before proceeding the AIV test, aggregate shall be cool in room temperature for atleast 30 minutes.
- Fill the cylindrical cup ( dia 75mm and depth 50mm ) in three equal layers, each layer shall be tempted by temping rod ( dia 10 mm, length 230 mm and rounded at one end) 25 times.
- After temping the third layer, surplus aggregate will be struck off with the help of temping rod using as a straight edge.
- Take the weight of these aggregate filled in cup and mention in report as a sample weight.
- After weighing same aggregates shall be transferred in steel cylindrical cup ( dia 102 mm and depth 50 mm ) and temped by temping rod 25 times.
- Then, after this cylindrical cup shall be shifted in impact value testing machine.
- By metal hammer we have to give 15 blows free fall.
- Make sure that Impact hammer falling distance is between limit means 375 to 385 mm up to top surface of aggregates. AIV hammer weight shall be between 14.5 to 15.0 kg.
- After 15 blows take that cup and shift crushed aggregates in 2.36 mm sieve kept in-tray.
- Sieve it for only one minute and take the weight of retained crushed aggregate carefully.
- Take the weight of passed material through 2.36 mm sieve.
- Add weight of retained and passed material, variation between added weight and sample weight shall not be more than 1 gram. If it happens, repeat the test.
- Do the test at least two times for average.
Calculation of Aggregate Impact value
sample weight (w1) = 352.0 gram
weight of retained on 2.36 mm (w2) = 71.0 gram
weight of passed material through 2.36 mm(w3) = 281.0 gram
w4 = w1-(w2+w3) = 0.0 gram
Aggregate impact value(%) = (w2/w1)*100 = 20.17 %
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Aggregate Impact Value Test Lab Report PDF
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Specification Limit of Aggregate impact value ( Range )
|Type of Mix||Limit||Specification|
|Concrete||30%||MORTH 5th, 1700 section|
|Grainular sub-base||40%||MORTH 5th, 400 section|
|Wet mix macadam||30%||MORTH 5th, 400 section|
|Bituminous macadam||30%||MORTH 5th, 500 section|
|Dense bituminous macadam||27%||MORTH 5th, 500 section|
|Bituminous concrete||24%||MORTH 5th, 500 section|
Our Practical Aggregate Impact Test Video
Viva Questions on Aggregate Impact Value Test
Q.1 What is the IS code for Aggregate impact test?
Ans. IS code for aggregate impact test is IS 2386 part 4.
Q.2 What is the weight of AIV hammer?
Ans. Hammer weight of AIV is between 14.5 to 15.0 kg.
Q.3 What is the falling height of AIV hammer?
Ans. Falling height of hammer is 380 +/- 5 mm.
Q.4 What sieves are required for AIV test?
Ans. Total three sieves are required for this test.
- 12.5 mm [ for sample sieving ]
- 10.0 mm [ for sample sieving ]
- 2.36 mm [ for after crushing ]
Q.5 How many strokes required by hammer in Aggregate impact testing machine?
Ans. Total 15 strokes required by hammer in Aggregate impact machine.
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