Aggregate Test and Its Equipment

Aggregate test and equipment used for those tests

Aggregate is an important part of construction which plays crucial role in forming the structures and provide strength to the composition.

There are certain quality tests which needs to be done to determine the quality of aggregates whether or not the available specimen is fit for usage or not.

These tests are:-

• Crushing test
• Abrasion test
• Impact test
• Soundness test
• Shape test
• Specific gravity and water absorption test
• Bitumen adhesion test

Crushing Test:

One of the model in which pavement material can fail is by crushing under compressive stress. A test is standardized by IS:2386 part-IV and used to determine the crushing strength of aggregates. The aggregate crushing value provides a relative measure of resistance to crushing under gradually applied crushing load. subjecting the specimen of aggregate in standard mould to a compression test under standard load conditions

Equipment used: Aggregate Crushing value

Abrasion Test:

Abrasion test is carried out to test the hardness property of aggregates and to decide whether they are suitable for different pavement construction works. Los Angeles abrasion test is a preferred one for carrying out the hardness property and has been standardized in India (IS:2386 part-IV). The principle of Los Angeles abrasion test is to find the percentage wear due to relative rubbing action between the aggregate and steel balls used as abrasive charge

Equipment Used: Los Angeles Abrasion Value apparatus

Impact Test:

The aggregate impact test is carried out to evaluate the resistance to impact of aggregates. Aggregates passing 12.5 mm sieve and retained on 10 mm sieve is filled in a cylindrical steel cup of internal dia 10.2 mm and depth 5 cm which is attached to a metal base of impact testing machine.

Equipment used: Aggregate Impact Value Apparatus

Soundness Test:

Soundness test is intended to study the resistance of aggregates to weathering action, by conducting accelerated weathering test cycles. The Porous aggregates subjected to freezing and thawing are likely to disintegrate prematurely. To ascertain the durability of such aggregates, they are subjected to an accelerated soundness test as specified in IS:2386 part-V.

Equipment Used: Waterbath

Shape Test:

The particle shape of the aggregate mass is determined by the percentage of flaky and elongated particles in it. Aggregates which are flaky or elongated are detrimental to higher workability and stability of mixes.

Equipment used: Flakiness index and Elongation index

Specific Gravity and Water Absorption Test:

The specific gravity and water absorption of aggregates are important properties that are required for the design of concrete and bituminous mixes. The specific gravity of a solid is the ratio of its mass to that of an equal volume of distilled water at a specified temperature. Because the aggregates may contain water-permeable voids, so two measures of specific gravity of aggregates are used: apparent specific gravity and bulk specific gravity.

Equipment Used: Specific Gravity Buoyancy Balance , Buoyancy balance

Bitumen Adhesion Test:

Bitumen adheres well to all normal types of road aggregates provided they are dry and free from dust. In the absence of water there is practically no adhesion problem of bituminous construction. Adhesion problem occurs when the aggregate is wet and cold. This problem can be dealt with by removing moisture from the aggregate by drying and increasing the mixing temperature.

Equipment Used: Stripping Value Apparatus