What Is Mean By AIV Test ?
To determine the Aggregate Impact Value (AIV) of aggregates
Uses of AIV Test ?
AIV Test mainly used For Following Two purposes
- To Find the impact value of the aggregates used in Road constructions and Buildings
- To find the strength Of the material
How to calculate the AIV value?
The AIV value is measured in the ratio between the sieved aggregate of 10mm & 2.36mm aggregates. The AIV test will be conducted as per the Indian Standard Code IS code 2386 Part 4.
What Are Apparatus used For Impact test ?
The equipment used for conducting the aggregate impact value test comprises of:
- The testing machine, which weighs between 45 and 60 kg, is equipped with a metal base featuring a flat lower surface measuring at least 30 cm in diameter. It is supported by a level and smooth concrete floor with a minimum thickness of 45 cm. Additionally, the machine’s base is designed to include provisions for secure fixation.
- The steel cup has an internal diameter of 102 mm, a depth (D) of 50 mm, and a minimum thickness (T)of 6.3 mm.
- The metal hammer, weighing between 13.5 and 14.0 kg, has a cylindrical lower end measuring 50 mm in length and 100.0 mm in diameter. The lower edge features a 2 mm chamfer and is case hardened. The hammer is designed to move freely between vertical guides and be concentric with the cup. The free fall of the hammer is set to be within 380±5 mm.
- The cylindrical metal measure is designed with an internal diameter of 75 mm and a depth of 50 mm specifically for measuring aggregates.
- The tamping rod is 10 mm in diameter and 230 mm long with one end rounded.
- The scale must have a minimum capacity of 500 g and be capable of reading and providing accurate measurements up to 0.1 g.
Important Points
- The aggregate sample must be completely dry.
- The cloth should be used to remove any dust from the sample aggregates.
- The tamping process should be carried out gently.
- It is necessary to wear a hand glove when handling the sample after it is removed from the oven.
- The test should begin once the sample has cooled down after being taken out of the oven.
- The hammer blows should be delivered 15 times, with each blow spaced at least 1 second apart.
Apparatus Required
♝ Impact Value Testing Machine ♝ Tamping rod ♝ Weighing balance ♝ Oven ♝ Sieves 12.5mm, 10mm & 2.36mm as per IS standard
Procedure For AIV Test
Step 1 First You must Sieve the Material Through 12.5mm Sieve and collect retaining material in 10mm Sieve.
Step 2 The sample must now undergo drying in the oven for a period of up to 4 hours at a temperature ranging from 100 to 110 degrees.
Step 3 The sample should be filled in the metal cup in three layers, with each layer being tamped 25 times using the tamping rod. Any excess sample should be removed from the metal cup.
Step 4 The weight of the combined sample in the metallic container should be recorded as W1.
Step 5 The sample with added weight was placed into the metal cup and then lightly tamped down.
Step 6 The metal cup is then positioned horizontally within the impact machine and secured in place to prevent any oscillation.
Step 7 The Impact test machine’s hammer is to be released, descending freely onto the sample. The process requires delivering 15 blows with intervals of less than 1 second each.
Step 8 Next, take out the metal cup from the machine and filter the aggregate using a 2.36mm sieve.
Step 9 Please proceed to measure the gathered samples as W2.
Result of AIV Test
Ratio of Impact Value = (W2/W1) x 100
At least two samples are required to conduct this test. The Impact Value of Aggregate is determined by calculating the average value of these two samples.
Record of observations
Interpretation of Results
The following AIV values for different types of road construction are recommended by IRC.
Format Book
