California Bearing Ratio (CBR) testing is a type of load-bearing test. It tests the soils at or just underneath the surface. Load-bearing tests work out how much weight the ground can take which can then be used to determine the safe bearing capacity of an area.

What is Involved in a CBR Test?

A CBR Test works by testing the pressure required to penetrate soil. This measurement is then divided by the pressure needed to achieve an equal penetration on a standard, high-quality crushed rock material. The harder the surface, the higher the CBR value is.

The test involves driving a small cylindrical plunger into the ground at a uniform rate, using a four-wheel-drive vehicle as the reaction load to provide the force. The CBR test can be carried out on soils with a maximum particle size of 20mm. Most tests are undertaken at surface level or at depths of 500 to 1000m. A minimum of three tests are normally carried out on a single site.

When would I Need a CBR Test?

Pavement Design

CBR testing is mostly commonly used to inform the design of highways and housing estate roads. As it determines the strength of the subgrade soil, it allows for the appropriate selection of suitable pavement thickness for the anticipated traffic density together with any precautions for frost heave.

Benefits of Choosing Your Environment

We have a vast amount of experience so you can be confident you are in safe hands.

• Our specialists work to British Standards and provide excellent value for money
• We conduct tests for different surfaces, including hand-held equipment tests
• You will get full reporting required for crane and piling companies
• We will guide you through the process if you’re not sure what you need
• We are fully insured to give you confidence and peace of mind


Need a CBR test? Contact us here to talk to a member of our team or request a free, no-obligation quote.