Grading of Soils
Lab Test
The Grading of Soils test determines the particle size distribution within a soil sample. By analysing the proportions of gravel, sand, silt, and clay, the test provides important information about the soil’s engineering properties. Understanding soil grading helps engineers assess its behaviour in construction applications, including compaction, drainage, and stability.

Enquire about this test

The Process

A representative soil sample is first dried and prepared in the laboratory. The sample is then passed through a series of sieves with progressively smaller openings to separate particles by size. For finer soils, additional methods such as sedimentation analysis may be used. The mass of material retained on each sieve is recorded and used to calculate the percentage of each particle size fraction.

The Reason

Particle size distribution has a major influence on soil performance. Well-graded soils typically compact more effectively and provide better load-bearing capacity, while poorly graded soils may have higher permeability or reduced stability. Grading analysis helps engineers classify soils and determine their suitability for specific construction purposes.

The Application

Soil grading is commonly assessed during ground investigations, earthworks, and pavement construction. The results help determine whether soils are suitable for use in subgrades, embankments, and engineered fill. They also support decisions relating to compaction requirements, drainage behaviour, and overall ground performance.

Frequently Asked Questions

What is the purpose of a soil grading test in construction?

A soil grading test identifies the distribution of particle sizes within a soil sample. This helps engineers determine whether the material is suitable for applications such as subgrades, embankments, and structural fill.

Can Amtest carry out soil grading tests for earthworks projects?

Yes. Amtest provides laboratory grading analysis for soils collected from construction sites, supporting earthworks investigations and compliance with project specifications.

How much soil is required for a grading test?

The required sample size depends on the particle sizes present in the soil. Amtest can advise on the appropriate sample quantity to ensure accurate grading analysis.

View more Aggregates testing services:

View all

Plastic Limit

Determination of the plastic limit of fine-grained soils in accordance with BS EN ISO 17892-12:2018+A2:2022.
BS EN ISO 17892-12:2018+A2:2022
Aggregates
UKAS Accredited
Lab Test
View Test

Particle Size Distribution

Determination of particle size distribution of aggregates using sieving in accordance with BS EN 933-1:2012.
BS EN 933-1:2012
Aggregates
UKAS Accredited
Lab Test
View Test

Sample Reduction

Sample reduction by riffle box, by quartering, or to a test portion of a specified mass within a small tolerance
BS EN 932-2:1999
Aggregates
UKAS Accredited
Lab Test
View Test

Dynamic Cone Penetration (TRL-DCP)

Rapid measurement of the in-situ strength of existing flexible pavements constructed with unbound materials.
DMRB, CS 229 Data for Pavement Assessment Rev.0: 2020
Aggregates
UKAS Accredited
Lab Test
Site Test
View Test

In-Situ California Bearing Ratio (CBR)

Penetration of soil with a plunger over a standard area. The harder the surface, the higher the CBR percentage.
Aggregates
Site Test
View Test

Constituents of Course Recycled Aggregates

Ensure the quality and compliance of recycled aggregates with our constituents analysis, supporting sustainable and reliable construction practices.
BS EN 933-11:2009
Aggregates
UKAS Accredited
Site Test
View Test

Plasticity Index

A higher Plasticity Index indicates a greater range of water content where soil remains plastic, signifying higher compressibility and potential for settlement.
BS EN ISO 17892-12:2018+A2:2022
Aggregates
UKAS Accredited
Lab Test
View Test

Water Content

Determination of the water content of aggregates in accordance with BS EN 1097-5:2008.
BS 1377-2:2022
Aggregates
UKAS Accredited
Lab Test
View Test

In-Situ Bulk Density Nuclear Method

The in-situ bulk density nuclear method ensures soil compaction meets construction standards by measuring density and moisture directly on-site.
BS 1377-9:1990
Aggregates
Site Test
View Test

Resistance to Fragmentation – Los Angeles Test

Subjects a coarse aggregate sample to abrasion, impact, and grinding.
BS EN 1097-2:2020
Aggregates
UKAS Accredited
Lab Test
View Test
Lab Test
Grading of Soils

The Grading of Soils test determines the particle size distribution of a soil sample, which is essential for understanding its compaction properties, permeability, and suitability for construction purposes.

The Process

  1. Sample Preparation: A representative soil sample is collected and prepared for sieving.
  2. Sieving: The soil sample is passed through a series of standard sieves with varying mesh sizes. The soil particles are separated based on their size as they fall through the sieves.
  3. Weighing and Calculation: The amount of soil retained on each sieve is weighed. The results are used to calculate the percentage of soil passing through each sieve, which is then plotted on a grading curve.
  4. Analysis: The grading curve is analyzed to determine the soil's classification and to assess its suitability for specific construction applications, such as foundations, roads, or embankments.

Why Is This Test Important?

  • Soil Classification: Helps classify soils based on their particle size distribution, which influences their suitability for different engineering applications.
  • Construction Suitability: Determines the soil's compaction and permeability properties, essential for road construction, foundations, and earthworks.
  • Quality Control: Ensures that the soil meets the specifications for strength, stability, and drainage.

The Grading of Soils test is a key method for determining the characteristics of soil used in construction, ensuring materials meet the required standards. Contact us for expert testing services.