A CBR test is a penetration test used to evaluate the subgrade strength primarily of roads, pavements and foundations. A CBR test often forms part of a comprehensive site investigation and helps determine the thickness of materials needed for the proposed construction.
How does a CBR Test work?
A CBR Test works by testing the pressure required to penetrate a soil sample with a plunger of the standard area and measuring this.
This measurement is divided by the pressure needed to achieve an equal penetration on a standard and high quality crushed rock material. The harder the surface, the higher the CBR value.
CBR tests can be carried out on soils with a maximum particle size of 20mm. Tests are typically conducted at surface level (depths between 500-1000m) in 20-30m intervals along the proposed construction centreline.
On a typical site with prepared surfaces, multiple CBR tests are completed by a single operator in a day. As a result, provisional results are often available on site.
When Do you Need a CBR Test?
CBR testing is part of the process of designing highways and housing estate roads. It can determine the strength of the subgrade soil and enable the appropriate selection of suitable pavement thickness for the anticipated traffic density and any precautions for frost heave.
What equipment do we use in CBR testing?
CBR Field Equipment consists of CBR Field Jacks, Load Rings, Surcharge Plates, and Penetration Pistons to provide penetration data from in-situ field tests. Other types of in-situ test can provide indicative equivalent CBR values such as plate load testing and dynamic cone penetration testing (DCP).
Who can provide CBR testing services?
TerraTek provides CBR testing services to a wide range of its clients. If you need a CBR test to help you in your project, we'd love to hear from you.