CBR testing carried out in line with British Standard BS 1377

Originally developed by the California Division of Highways in the 1930s and covered within British Standard BS1377, the California Bearing Ratio test – or CBR test – is an in-situ construction materials test designed to assess the load-bearing capabilities of roads, pavements, driveways and so on. It is widely accepted as being the ‘go to’ test for the simulation of traffic, providing useful information on the effects such activity might have upon component layers.

A penetration test critical for road design and materials calculations, in basic terms, the CBR test involves a piston of a known size being applied to a sample of soil at a specified rate. The CBR value is then calculated, in part, based upon the ease with which the piston penetrates the soil. Whilst CBR testing can be used when a change of use is being considered (e.g. heavier or increased traffic), it is also commonly utilised to assess the volume of materials required should contractors be looking to construct a new road.

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    CBR Testing


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    • We generally issue plates reports within 2 working days, but we can issue the next working day where possible and upon request.

    • CBR tests are commonly used in road construction and when designing subbase layers. Incremental plate load tests are usually used for obtaining ground bearing capacity, often on piling mats or crane mats.

    • CBR stands for California Bearing Ratio. The test was developed by the Californian Division of Highways (now known as Caltrans) between the years of 1928 and 1929. The point of the test was to help guarantee that roads could be built as economically as possible whilst still being able to cope with the necessary loads. The result is a percentage of the actual load causing penetration of 2.5mm on a standard crushed rock sample.

    • We're based in Watford in Hertfordshire, not far from London, but we regularly travel throughout the UK including Bedfordshire, Middlesex, Buckinghamshire and Surrey to support our clients.

    • Whilst every project is different, we charge based on a competitive day rate. Simply get in touch for a tailored quotation.

    • Many of our clients are initially unsure as to exactly what type of testing is needed to capture the information their projects require. If that sounds like you, just get in touch and a member of our team will advise on the most appropriate and cost-effective approach to take.

    • Absolutely. Whilst the majority of our works are carried out during normal working hours between Monday and Friday, we understand that this won't be possible for every client. That's why we offer an out of hours and weekend working service available upon request.

    • On the whole, our lead time for site work is between 1-2 weeks from receipt of an instruction. That said, we completely understand that some projects require a more immediate response and will always do our best to accommodate urgent requests.

    • Yes. All of our engineers are trained to work at height with PASMA and IPAF certification. We can also bring any necessary access equipment with us - such as a tower or MEWP - as necessary.

    • Yes. We have a number of highly experienced engineers who have confined space training.

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    Time served professionals

    Every one of our engineers and technicians has at least 10 years' experience in structural investigation, scanning and materials testing.

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    Professional, friendly staff

    We take pride in the professionalism and attitude of our staff. From first contact to reporting, we'll treat you as we'd like to be treated ourselves.

    Proven track record

    Every year, we complete hundreds of projects for a truly loyal client base, firms that return time after time, confident in the service they'll receive.

    Nationwide service

    Our teams travel the length and breadth of the UK, delivering structural investigation and testing services on a truly diverse range of sites.

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    Using the very latest technology and techniques, we help reduce unexpected costs, keeping your team, project and organisation safe in the process.

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    — Ben Joshua, Senior Engineer, Keltbray

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    — Malcolm Brady, Director, MBP

    "I have worked with Perry Testing Limited on several projects over the past 3 or 4 years, and they have always responded to our requests at very short notice, providing a professional, expert service every time."

    — Ben White, Managing Quantity Surveyor, United Living

    CBR Testing

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