It was developed by the California Division of Highways in the 1930’s and has been the standard method adopted in the UK for assessing the strength of subgrade and subbase materials for many decades. The test is specified in BS1377: Part 9: 1990: Soils for civil engineering purposes.

This service is for construction contractors and civil engineers.

How is a CBR test done?

The basic site test is performed by measuring the pressure required to penetrate soil with a plunger over a standard area. The measured pressure is then divided by the pressure required to achieve an equal penetration on a standard crushed rock material. The harder the surface, the higher the CBR percentage.

Tests are carried either in situ or on samples taken and returned to the laboratory. The results obtained are compared with the curves of a standard test to give an idea of the strength of the subgrade soil. The California Bearing Ratio is measured at various points on the construction site (usually at around 30 metre intervals for new road construction

How long does it take to get the results?

Our new system for CBR and plate load testing ‘Baseplate’ has been designed in-house by our expert software development team.  It allows results to be entered on site via laptops into a dedicated application that allows instant calculation and upload of results to our dedicated client portal for validation.   When testing is complete a site attendance form is immediately emailed to the client detailing preliminary results found.  Once validated the final UKAS accredited report is then able to be issued, usually on the same day as the testing was carried out. 

The client is then given their own user name and password to access their own area of the portal where they can retrieve all historical tests reports that have been carried out for them using the system.

  • We're based in Derby, in The Midlands, and operate all over the UK
  • We're known for our prompt, reliable and competitively priced service
  • Our plate bearing test reports are usually being issued within one working day of the site visit