The Plate Bearing Test Explained
Variations of this simple test are used throughout the world, and are usually known as the Plate Bearing or Plate Loading Test. The UK version is based upon the American model which utilizes a variety of circular plates up to 30” (760mm) diameter. The plates are loaded by hydraulic jack and settlement measured in increments. A graph is plotted of settlement against bearing pressure.
What does the Plate Bearing Test actually test?
It measures settlement under load on soils, fill and sub-base to determine whether the ground has sufficient bearing capacity. This enables you to get reading such as equivalent CBR (California Bearing Ratio) on materials that are too large for a standard CBR tests.
Why would I need to do a Plate Bearing Test?
If you are planning to erect a structure or heavy plant on land that you are not sure has enough bearing capacity – for example on imported fill, this test will give you peace of mind and certification to prove that the land is suitable, or give you the information you need to make further provisions. Typical examples include ensuring that buildings won’t suffer excessive settlement once constructed, or that large equipment, such as cranes and piling rigs, can be supported by the ground.
What standards does the Plate Bearing Test meet?
Various national standards apply including British Standard BS1377 Part 9 and ASTM D1194, but the test can be modified to suit your specific requirements.
What is the procedure for the Plate Bearing Test?
In order to perform this test it is important to have sufficient kentledge to jack against to test bearing capacity. This could be equipment you have on site such as a 360⁰ excavator, a mobile crane or a wagon loaded with material. The choice of plate size depends upon required bearing pressure and availability of kentledge. Values are based upon using a 30” plate but practical consideration usually precludes its use and 24” is the most commonly used. Conversion factors can be applied to convert readings from any plate size to an equivalent 30”.
Typical uses for the plate bearing test;
- Roads and Car Parks, all levels below asphalt or concrete
- Buildings and structures – all levels below foundations and ground floor slabs
- Mobile Crane mats
- Piling Mats
- In situ formation
- As dug site fill
- Imported general fills and stone such as 6F2
- MoT quality sub-base
What do I get as a result of the Plate Bearing Test?
This information is used to calculate the Modulus of Subgrade Reaction, known as the K value, which is expressed as load per unit area per unit of settlement e.g. N/mm2/mm. The resulting graph will show settlement at any given load and will project whether the ground is suitable for your planned construction. The readings can also be used to calculate various other values, particularly equivalent CBR (California Bearing Ratio) on materials too large for standard CBR tests.
How long does all this take?
From us arriving on site to perform the Plate Bearing Test, to issuing our Certificate of Test can normally be achieved within a 24 hour period. Draft results can be available the same day.
We can often perform those tests on a next day or even same day basis, but a few days is preferable to guarantee availability.
To avoid delays, you will need to have the ground fully prepared and suitable kentledge available when we arrive to perform the plate bearing test. [/DDET]
What do I do with the results of a Plate Bearing Test?
The certified results can be compared with specified compliance values or used as the basis of further calculations to determine necessary action on site e.g. increased thickness of sub-base layer.
- Relatively quick, straightforward and inexpensive
- Can be performed on a wide variety of materials
- Results available same day
- Adaptable to specific requirements
- Dependent upon the provision of suitable Kentledge
- Not a substitute for proper site investigation at design stage
Sounds like what I need, what do I do next?
If you would like to arrange a plate bearing tests or enquire please follow the link or call us on 01405 860905
I’m still not sure if I need a Plate Bearing Test, can you help me?
Just give us a call and we’ll try to explain further and arrange the most suitable test for your needs. For more information on CBR Test, click here
Typical uses for plate bearing tests;