What is the California Bearing Ratio?
The California Bearing Ratio (CBR), as outlined in BS 1377-9, is a standardised test used to measure the load-bearing capacity of soil or pavement materials. Essential for road construction and foundation design, this test determines the thickness of materials required for projects such as roads, car parks, runways, and pavements. Developed by the California State Highway Department in the 1930s, the CBR test involves a penetration procedure that simulates real-world stresses.
At PSL, we specialise in conducting California Bearing Ratio tests using:
- Vehicle-mounted frames
- JCB attachments
Why Your Project Needs a CBR Test
Roads & Pavements
A California Bearing Ratio (CBR) test is critical for road and pavement projects. This test evaluates the strength and load-bearing capacity of the highway sub-base and subgrade soil. By replicating vehicular stress on soil, the CBR test determines the appropriate thickness of construction materials. This ensures the durability and longevity of the roadway or pavement under regular traffic loads.
Foundations
In civil engineering, the stability and strength of the soil beneath any structure are crucial for safety and regulatory compliance. A CBR test provides vital insights into the suitability of the ground for your construction project. The test results help determine whether additional reinforcement is required to enhance stability, ensuring your project meets safety and structural requirements.
Expert On-Site Testing by PSL
Our team of expert technicians conducts California Bearing Ratio tests on-site, using specialised equipment. We employ either a 4-wheel-drive vehicle or a JCB attachment to transport the testing apparatus and apply the necessary force.
The procedure includes:
- Preparing the testing surface.
- A cylindrical plunger is inserted into the ground to measure penetration resistance at regular intervals.
- Comparing the measured pressure to a standard pressure value obtained from crushed rock material.
At least three tests are performed to ensure accurate results. Under optimal conditions, technicians can conduct 8 to 10 tests per day. Preliminary results are provided on-site for immediate analysis.
Why Choose PSL for Your California Bearing Ratio Testing?
With years of expertise, PSL ensures precise and reliable CBR testing for your projects.
From roads to foundations, our tests help you make informed decisions about materials and construction techniques.
Choose PSL for your California Bearing Ratio needs.
Get in touch today to discuss your project and let our team of experts provide you with reliable California Bearing Ratio testing
Frequently Asked Questions
How is a CBR test conducted?
To perform a California Bearing Ratio test:
- Prepare the apparatus: Assemble the CBR machine with a penetration piston and load gauge.
- Conduct the test: Gradually apply load and measure penetration at specified depths (e.g., 2.5 mm and 5.0 mm).
- Analyse the data: Calculate the CBR by comparing the measured load with standard values.
- Interpret the results: Use the calculated CBR to assess the soil's suitability for the intended use.
Is a CBR test the same as the Plate Bearing Test?
No, the CBR test and the Plate Bearing Test serve different purposes and use distinct methods:
- CBR Test: Measures soil strength and penetration resistance, often in a lab also in-situ, mainly for roads, pavement and subgrade evaluations.
- Plate Bearing Test: Directly evaluates soil bearing capacity and settlement behavior on-site, used for foundation design and structural assessments.
