# Aggregate Test Calculators

## Sieve Analysis of Aggregates

A sieve analysis (or gradation test) is a practice or procedure used to assess the particle size distribution (also called gradation) of a granular material by allowing the material to pass through a series of sieves of progressively smaller mesh size and weighing the amount of material that is stopped by each sieve as a fraction of the whole mass.

##### Why to do Sieve analysis of Aggregates?

Particle size determinations on large samples of aggregate are necessary to ensure that aggregates perform as intended for their specified use. A sieve analysis, or gradation test determines the distribution of aggregate particles by size within a given sample. This information can then be used to determine compliance with design and production requirements. Data can also be used to better understand the relationship between aggregates or blends and to predict trends during production.

## Aggregate Crushing Value

The aggregate crushing value provides a relative measure of resistance to crushing under a gradually applied compressive load. To achieve a high quality of pavement, aggregates possessing low aggregate crushing value should be preferred.
##### Why to test Aggregate Crushing Value?

The principal mechanical properties required in road stones are:

• Satisfactory resistance to crushing under the roller during construction
• Adequate resistance to surface abrasion under traffic. Also surface under rigid type of heavily loaded drawn vehicles are high enough to consider the crushing strength of road aggregates as an essential requirement in India

Crushing strength of road stone may be determine either on aggregates or on cylindrical specimen cut out of rocks. The two tests are quite different not only in the approach but also in the expression of the results. Aggregate used in road construction, should be strong enough to resist crushing under traffic wheel loads. If the aggregates are weak the stability of the pavement structure is likely to be adversely affected. The strength of coarse aggregates is assessed by aggregate crushing test.

## Aggregate Impact Value

The aggregate impact value indicates a relative measure of the resistance of an aggregate to a sudden shock or an impact, which differs from its resistance to a slow gradually increasing compressive load.

##### Why to test Aggregate Impact Value?

Toughness is the property of a material to resist impact. Due to traffic loads the road stone are subjected to the pounding action of impact and there is possibility of breaking into smaller pieces. The road stone should therefore be tough enough to resists fracture under impact. A test designed to evaluate the toughness of stones i.e. the resistance of the stones to fracture under repeated impacts may be called an impact test for road stones.

## Aggregate Crushing Value

The aggregate crushing value provides a relative measure of resistance to crushing under a gradually applied compressive load. To achieve a high quality of pavement, aggregates possessing low aggregate crushing value should be preferred.
##### Why to test Aggregate Crushing Value?

The principal mechanical properties required in road stones are:

• Satisfactory resistance to crushing under the roller during construction
• Adequate resistance to surface abrasion under traffic. Also surface under rigid type of heavily loaded drawn vehicles are high enough to consider the crushing strength of road aggregates as an essential requirement in India

Crushing strength of road stone may be determine either on aggregates or on cylindrical specimen cut out of rocks. The two tests are quite different not only in the approach but also in the expression of the results. Aggregate used in road construction, should be strong enough to resist crushing under traffic wheel loads. If the aggregates are weak the stability of the pavement structure is likely to be adversely affected. The strength of coarse aggregates is assessed by aggregate crushing test.

## Aggregate Abrasion Value

Due to the movement of traffic, the road stones and used in the surfacing course are subjected to wearing action at the top Resistance to wear or hardness is hence an essential property of road aggregate, especially when used in wearing course. Thus road stones should be hard enough to resist the abrasion due the traffic. When fast moving traffic fitted with pneumatic tyres move on the road, the sod particles present between the wheel and road surface causes abrasion on the road stone. Steel tyres of the animal drawn vehicles which rub against the stones can cause considerable abrasion of the stones on the road surface Hence in order to tests are carried out in the laboratory.

## Aggregate Water Absorption Test

Water absorption gives an idea of strength of aggregate. Aggregates having more water absorption are more porous in nature and are generally considered unsuitable unless they are found to be acceptable based on strength, impact and hardness tests. Water absorption shall not be more than 2% per unit by weight. In case in Water absorption is higher than 2% than soundness test is required.