Procedure of Aggregate Impact Value Test

The Aggregate Impact Value (AIV) test is a procedure conducted to determine the resistance of an aggregate to sudden impact or shock. This test is crucial in determining the quality and durability of aggregates for use in construction. In this article, we will discuss the complete procedure of conducting an AIV test, from the introduction to the calculations at the end.

Introduction to Aggregate Impact Value Test

The AIV test is a crucial test used to evaluate the toughness and resistance of aggregates against sudden impact loads. The primary purpose of this test is to ensure that only durable and robust aggregates are used in construction. The test involves the use of a testing machine to subject the aggregates to impact loads. The machine comprises a base, cylindrical measure, and a hammer that falls through a given height to cause an impact on the aggregates. The results of this test are expressed in terms of the aggregate impact value, which helps in determining the quality of the aggregates.

The AIV test is a widely recognized and accepted method for evaluating the quality of aggregates used in construction. The test is used to determine the strength and durability of aggregates and to ensure that they can withstand the impact loads they will be subjected to during the construction process.

Purpose of the Test

The primary purpose of the AIV test is to determine the resistance of an aggregate to sudden impact loads. The test helps to ensure that only durable and robust aggregates are used in construction, as such aggregates can withstand the sudden impact loads experienced during the construction process.

Impact loads can occur during the construction process due to various factors such as the weight of heavy machinery, vehicles, and equipment, as well as the impact of falling objects. Therefore, it is essential to use aggregates that can withstand these loads to ensure the safety and longevity of the structure being built.

Importance in Construction Industry

The quality of aggregates used in construction is critical. The use of poor quality aggregates can result in structural failure and costly repairs. Therefore, conducting an AIV test is crucial to ensure that the aggregates being used are of sufficient quality to withstand the impact loads they will be subjected to during construction.

The AIV test is widely used in the construction industry to ensure that the aggregates being used meet the required standards and specifications. The test helps to identify any potential weaknesses in the aggregates and ensures that only the most durable and robust aggregates are used in construction.

In addition to ensuring the safety and longevity of the structure being built, using high-quality aggregates can also result in cost savings. The use of durable and robust aggregates can reduce the need for repairs and maintenance, resulting in lower overall costs.

Overall, the AIV test is an essential tool for ensuring the quality and durability of aggregates used in construction. By conducting this test, construction professionals can ensure that the structures they build are safe, long-lasting, and cost-effective.

Apparatus and Materials Required

The following apparatus and materials are required to perform an AIV test:

Aggregate Impact Testing Machine

The testing machine consists of a steel cylinder with an internal diameter of 15.6 cm, mounted on a base frame. The hammer falls freely from a height of 38 cm to impact on the aggregates. The machine is designed to provide a uniform impact on the aggregates and is capable of determining the aggregate’s resistance to impact.

The machine is widely used in the construction industry to test the quality of aggregates used in the production of concrete. The test results help to ensure that the aggregates used in construction projects meet the required standards and are suitable for use in the construction of roads, buildings, and other structures.

Cylindrical Measure and Tamping Rod

The cylindrical measure used in this test should be of IS code 2386 (Part IV). The measure should be 11.5 cm in diameter and 18 cm in height. The tamping rod should have a 16 mm diameter and a length of 45 cm. The cylindrical measure is used to measure the volume of the aggregates, while the tamping rod is used to compact the aggregates in the measure.

The cylindrical measure and tamping rod are essential components of the AIV test. They help to ensure that the aggregates are properly compacted and that the test results are accurate.

Sieves

The sieves used in this test should be of IS code 2386 (Part I). The size of the sieves should be 12.5 mm and 10 mm. The sieves are used to separate the aggregates into different size fractions. The aggregates that pass through the 12.5 mm sieve are retained on the 10 mm sieve.

The sieves are an important component of the AIV test. They help to ensure that the aggregates are properly graded and that the test results are accurate.

Sample Preparation

The sample used in the AIV test should consist of aggregates that are evenly graded, with a maximum size of 12.5 mm. The sample should be obtained by taking a minimum of 20 kg from the parent aggregate. The sample should be washed and dried before testing.

The sample preparation is a crucial step in the AIV test. It helps to ensure that the test results are accurate and that the aggregates used in construction projects meet the required standards.

Test Procedure

The Aggregate Impact Value (AIV) test is an important test used to determine the durability and resistance of aggregates to sudden impact loads. The procedure for conducting this test involves several steps:

Step 1: Sieving the Aggregates

The first step in conducting the AIV test is to sieve the aggregates through the 12.5 mm and 10 mm sieves. This is done to ensure that only the appropriate size of aggregates is used for the test. The weight of the aggregates passing through each sieve should be measured and noted down.

It is important to note that the sieves used should be clean and free from any dust or other particles. This is to ensure that the test results are accurate and reliable.

Step 2: Preparing the Test Sample

After sieving the aggregates, a sample weighing 3 kg should be taken for the test. This sample should be dried in an oven at a temperature of 100-110°C for four hours. After drying, the sample should be cooled down to room temperature before use.

It is important to ensure that the sample is completely dry before conducting the test. Any moisture in the sample can affect the test results and lead to inaccurate readings.

Step 3: Filling the Cylindrical Measure

The next step is to fill the cylindrical measure with the dried sample in three layers. Each layer should be tamped with the tamping rod 25 times before adding the next layer. The top of the measure should be leveled using a straight-edge.

It is important to ensure that each layer is evenly distributed and tamped properly. This is to ensure that the sample is compacted uniformly and the test results are accurate.

Step 4: Compacting the Sample

The sample in the cylindrical measure should be compacted by giving 15 blows of the hammer. The blows should be evenly distributed over the surface of the aggregate, and care should be taken to avoid unnecessary chattering of the cylinder.

It is important to ensure that the blows are evenly distributed and that the cylinder is not chattered. This is to ensure that the sample is compacted uniformly and the test results are accurate.

Step 5: Conducting the Impact Test

The impact test should be carried out by allowing the hammer to fall onto the aggregate sample in the cylindrical measure. The machine should be operated at a uniform rate of 15 blows per minute. After 15 blows, the crushed material should be removed from the cylinder and sieved through a 2.36 mm sieve. The weight of the material passing through the sieve should be noted down.

It is important to ensure that the machine is operated at a uniform rate of 15 blows per minute. This is to ensure that the test results are accurate and reliable. It is also important to ensure that the crushed material is removed from the cylinder and sieved through a 2.36 mm sieve to determine the weight of the material passing through the sieve.

Step 6: Calculating the Aggregate Impact Value

The aggregate impact value is calculated by subtracting the weight of the material passing through the 2.36 mm sieve from the original weight of the sample. The result is then divided by the initial weight of the sample and expressed as a percentage.

It is important to ensure that the calculations are done accurately and that the test results are recorded properly. This is to ensure that the test results are reliable and can be used to determine the durability and resistance of aggregates to sudden impact loads.

Overall, the AIV test is a crucial test for evaluating the durability and resistance of aggregates to sudden impact loads. By following the correct procedure for conducting this test, the quality of aggregates used in construction can be ensured, resulting in structures that are stronger and more durable.