Particle Size (grading)

The particle size distribution test for soil and aggregates to establish its grading

This is the most common test to establish compliance against a specification, but also to be able to predict the properties of a soil, aggregate or fill.

For particles sizes from 150mm down to 0.063mm a test sample would be washed and then passed through sieves with increasing smaller apertures and then each size fraction weighed. If the size and percentage of particles smaller than 0.063mm is required to be known then this can be undertaken by a couple of other means. Generally a sample would be considered a gravel if the majority of particles are greater than 2mm, a sand if most the particles are between 2mm and 0.063mm, a silt if it's between 0.063 and 0.002mm and a clay if its finer than 0.0002mm.

We can undertake this type of testing in a variety of methods for soils and aggregates including wet and dry sieving and hydrometer analysis.

The classification test

A really useful test in wide use for establishing properties of materials

Find out if its clay, silt or sand

Knowing the particle size distribution will mean you know a great deal about the performance of the material.

The test for specification compliance

Almost every specification will have a grading requirement so you will need this test!