CBR Testing in Newcastle at a Glance

  • What we do: on-site California Bearing Ratio (CBR) tests and plate load tests
  • Where: Newcastle upon Tyne, Gateshead, Sunderland, Durham, Northumberland and Teesside
  • Standard: BS 1377: Part 9: 1990, Soils for civil engineering purposes
  • Results: same day
  • Price: one fixed rate per test, whatever the location of your site
  • Experience: over 20 years of testing for the construction industry
  • Clients: civil engineers, structural engineers, groundworks contractors, housebuilders and developers

 

What is CBR Testing?

CBR stands for California Bearing Ratio. A CBR test is a penetration test used to determine the strength of the ground beneath a road, pavement, car park or hardstanding. It was developed by the California Division of Highways in the 1930s and is still the standard way to assess soil strength on UK construction projects. Our CBR testing follows British Standard BS 1377: Part 9, so your results are produced to a recognised method.

During the test, a load is pushed into the soil at a steady rate and the force needed is recorded. That force is compared with the force needed to achieve the same penetration in a standard crushed rock material, and the result is given as a percentage. Simply put, the harder the surface, the higher the CBR value. The CBR value indicates the soil’s load-bearing capacity, which is its ability to withstand loads from traffic, plant and structures. A low CBR value typically indicates weak soils such as wet clay, while high CBR values indicate strong ground or high-quality sub-base materials.

CBR testing is critical for road design, car parks and foundations, and CBR results are required by many UK civil engineering standards and specifications. Engineers use the CBR value to decide how thick the capping, sub-base and surfacing need to be. Accurate CBR tests help prevent excessive settlement during construction and avoid the costs of over-engineering or under-engineering, which makes testing one of the most cost effective steps in any project.

How We Carry Out CBR Tests on Site

Our CBR testing services follow the same clear process on every Newcastle site:

  1. Tell us about your project. We ask where the site is, what is being built, what material is being tested and how many tests your engineer has specified.
  2. Prepare the test locations. Tests are undertaken at formation level, either at the surface or at depth in shallow trial pits. Each location needs to be level and undisturbed.
  3. Apply the load. Working against a reaction load, usually an excavator or heavy vehicle, we load the ground with a plunger or steel plate and record the load and settlement using calibrated gauges.
  4. Calculate the CBR value. Readings are converted into a CBR percentage for each location. Where a plate bearing test is used, an equivalent CBR value is calculated from the results.
  5. Report the results. You receive your results the same day, so your engineer can confirm the design and your project can proceed safely without delay.

 

Any grading, compacting or change in moisture after the test can alter the strength of the soil, so we always recommend testing as close as possible to the start of construction.

CBR Test or Plate Bearing Test: Which Do You Need?

Both tests assess how the ground performs under load, but they suit different materials and different jobs. We carry out both and will advise which is right for your site.

In-situ CBR test Plate bearing test (plate load test)
Best for Fine-grained soil such as clay, silt and sand, with particles up to 20mm Coarse granular fill, crushed rock, made ground and working platforms
What it measures Resistance to penetration, reported as a CBR percentage Settlement under an increasing load, used to assess bearing capacity (the load the soil can support before failure) and equivalent CBR
Typical uses Roads, car parks, driveways, footpaths and hardstandings Crane outriggers, piling mats, working platforms, temporary works and foundations
Equipment CBR plunger and reaction load Steel plate of 300mm, 450mm or 600mm diameter, hydraulic jack and reaction load

 

Find out more about plate load testing and our full range of CBR testing services.

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Ground Conditions in Newcastle and the North East

Ground conditions affect the design of foundations, roads and structures, and no two sites are the same. Ground conditions vary significantly across Newcastle, so CBR testing needs to be tailored to each site. Much of Newcastle is underlain by glacial till, the stiff boulder clay left behind by the last ice age, sitting over Coal Measures rock. Softer alluvial silts and clays follow the River Tyne, and many development sites along the Quayside, in the Ouseburn valley and on former colliery and industrial land include made ground of varying quality.

This matters for CBR testing in three ways:

  • Clay strength changes with moisture. The same boulder clay can give a good CBR value in a dry summer and a poor one after a wet winter. Testing at formation level, at the time of construction, gives you a figure you can rely on.
  • Made ground is unpredictable. Fill on brownfield sites can vary over a few metres. More test locations, or plate load tests on coarse fill, give a truer picture of the underlying ground.
  • CBR tests only assess shallow ground. A plate bearing test tells you about the ground to a depth of roughly one and a half to two times the plate diameter. It does not replace a site investigation or a coal mining risk assessment, which is often needed for planning permission in former mining areas.

Where CBR Testing Fits in a Site Investigation

On larger developments, CBR testing is one part of a wider geotechnical and geo environmental investigation. Site investigations assess soil and rock properties, and help inform foundation design and any remediation needs. A typical project runs in three stages:

  1. Phase 1 desk study. A desk study and preliminary risk assessment reviews the history of the property, including past mining and the possible presence of contamination.
  2. Phase 2 intrusive site investigation. Phase 2 investigations follow the Phase 1 desk study. Boreholes, window sampling and trial pits are used to recover soil samples, which are analysed for contamination and geotechnical properties by laboratory testing. Where the risk assessment calls for it, monitoring wells are installed to check for ground gas such as methane and carbon dioxide.
  3. CBR and plate load testing. Once levels are known, CBR tests are undertaken at formation level to confirm the design assumptions before construction starts.

 

We provide the intrusive investigation, the laboratory testing and the on-site CBR testing. Our site investigation techniques include window sampling, borehole drilling, rotary drilling and coring, dynamic probing and concrete coring. If your consultant has already completed the desk study, send us the specification and we will price the fieldwork.

When is a CBR Test or Plate Load Test Required in Newcastle?

CBR tests are undertaken whenever the ground has to support traffic or plant. The most common projects we test for in the North East are:

  • New roads and estate roads. Local authorities often ask for CBR results as part of the pavement design for roads put forward for adoption.
  • Car parks, service yards and hardstandings for retail, industrial and warehouse development.
  • Driveways, footpaths and cycleways, including permeable paving schemes.
  • Crane outriggers, piling mats and working platforms, where testing is essential and a plate load test is used to confirm the ground can carry the proposed load.
  • Temporary haul roads and compounds on larger building and infrastructure projects.
  • Extensions and alterations where new paving or slabs are proposed next to existing foundations.

 

If you are unsure whether you need a CBR test, a plate bearing test or a wider intrusive site investigation, call us and we will talk it through.

What Do CBR Results Mean?

CBR results are given as a percentage. As a general guide:

CBR value What it means Typical ground
Below 2% Very weak. The ground normally needs improving or replacing before construction. Soft, wet clay and silt
2% to 5% Weak to moderate. A thicker capping layer and sub-base is usually needed. Firm clay
5% to 15% Fair to good subgrade for most roads and car parks. Stiff clay, sand
Above 15% Strong ground that needs a thinner construction. Dense sand and gravel, well compacted fill

 

For highway work, National Highways design guidance (CD 225) treats a subgrade with a CBR below 2.5% as too weak to build on without improvement. Your engineer will use the tested values, together with the expected traffic, to design the pavement.

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Site Investigation Services and Laboratory Testing in Newcastle

Our CBR testing expertise is part of a comprehensive range of geotechnical testing services for the civil engineering and construction industries, from site investigation services through to laboratory testing:

 

Areas We Cover Around Newcastle

Newcastle is covered by our Yorkshire and North East team. We regularly test sites in:

  • Tyneside: Newcastle upon Tyne, Gateshead, North Shields, South Shields, Wallsend, Jarrow and Whitley Bay
  • Wearside: Sunderland, Washington and Houghton-le-Spring
  • County Durham: Durham, Chester-le-Street, Consett and Newton Aycliffe
  • Northumberland: Cramlington, Blyth, Morpeth, Ashington and Hexham
  • Teesside: Middlesbrough, Stockton-on-Tees, Hartlepool and Darlington

 

Not on the list? We provide testing services nationwide, so get in touch wherever your site is. You can also see all of our locations.

Benefits of CBR Testing in Newcastle with STS

  • Over 20 years of experience. We have been providing CBR and plate testing to the construction industry for more than two decades.
  • One fixed rate. You pay the same rate per test regardless of where your site is.
  • Same day results. Your engineer gets the figures quickly, so the programme keeps moving.
  • One team for site and laboratory. CBR tests, plate tests, investigation and laboratory analysis from a single supplier.

 

Our clients say it best: “I have used STS on various schemes over the last few years and have always found them to be professional, give great service and will go out of their way to accommodate should difficult situations arise.” Tony Pate

 

CBR Testing Newcastle FAQs

What does CBR testing stand for?

CBR stands for California Bearing Ratio. It is a penetration test that measures the strength of soil and sub-base, named after the California Division of Highways, which developed it in the 1930s.

What does a CBR test tell you?

A CBR test tells you how strong the ground is at formation level. Engineers use the result to determine the thickness of capping, sub-base and surfacing needed for a road, car park or hardstanding.

What is a good CBR value?

For natural ground, a CBR of 5% or more is generally considered a reasonable subgrade, and 15% or more is strong. Below 2.5% the ground normally needs improvement. The value you need depends on the design, so always confirm it with your engineer.

What does 5% CBR mean?

A CBR of 5% means the soil offers 5% of the resistance of the standard crushed rock used as the benchmark. It is typical of firm clay and is usually acceptable for roads and car parks with a suitable capping and sub-base.

What does 15% CBR mean?

A CBR of 15% means the ground offers 15% of the resistance of the standard crushed rock. It indicates strong ground, such as dense sand or well compacted fill, and normally allows a thinner construction.

How much does a CBR test cost in Newcastle?

We charge one fixed rate per test, whatever the location, so a site in Newcastle costs the same as one anywhere else in the UK. The total depends on how many tests you need and the type of test. Call 0333 567 1388 for a free, no obligation quote.

How long does a CBR test take?

Each test typically takes around 20 to 30 minutes once the equipment is set up, so several locations can usually be completed in a single visit. Results are provided the same day.

How many CBR tests do I need?

The number and spacing of tests is set by your engineer or the adopting authority. Send us the specification or drawing and we will price exactly what is required.

What do I need to provide on site?

Clear access to each test location, the ground exposed at the level to be tested, and a reaction load such as an excavator. We confirm exactly what is needed when you book.

Do you test working platforms and crane outriggers?

Yes. We use a plate load test to assess whether a working platform, piling mat or crane outrigger position can carry the proposed load. Tell us the plant being used and the loads involved when you call.

Can CBR tests be carried out in wet weather?

Yes. However, moisture affects soil strength, so results reflect the ground conditions on the day. Protect the formation from standing water before the test wherever possible.

Contact Us Today for CBR Testing Newcastle

We are a team of CBR testing experts covering Newcastle and the North East, committed to giving you accurate CBR and plate bearing readings and clear advice.

Call 0333 567 1388 or 07301 592141, or contact us today for a free quote.