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Plate Bearing Tests 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.
Why would I need to do this 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
wont suffer excessive settlement once constructed, or that large
equipment, such as cranes and piling rigs, can be
supported by the ground.
What standards does it 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 this test?
In order to perform this test it is important to have
sufficient kentledge to jack against. This could be
equipment you have on site such as a 360 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.
What do I get as a result of the 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.
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How long does all this take?
From us arriving on site to issue or our Certificate of Test can
normally be achieved with 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.
What do I do with the results?
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.
Advantages
Relatively quick, straightforward and inexpensive
Can be performed on a wide variety of materials
Results available same day
Adaptable to specific requirements
Limitations
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
Im still not sure, can you help me?
Just give us a call and well try to explain further and arrange
the most suitable test for your needs.
Typical uses for plate bearing tests;
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
Typical Materials
In situ formation
As dug site fill
Imported general fills and stone such as 6F2
MoT quality sub-base
