PRIMA Subsoil 531

When to use PRIMA 100

Test your subsoil: avoid unforeseen expenses

Wherever you construct a road, the present subsoil is your basis. Knowing its properties is vital for the quality of the finished road. Measuring bearing capacity is essential. The PRIMA 100 Light Weight Deflectometer offers a reliable and easy method.

Subsoil characteristics control will either confirm your assumptions or be a surprise to you. Having the bearing capacity confirmed will allow you to sleep well at night and at this early stage in road construction phase a surprise is better than finding that the performance of the road is beginning to fail much earlier than you would have expected.

Measuring PRIMA100 200On a lucky day you will find out that generally the subsoil bearing capacity along your track is considerably better than expected. This gives you a chance of saving money as the thickness of the sub-base or the base course may be reduced. However, you should still observe the risk of frost in areas where this occurs.

You may feel less lucky the day you find subsoil with a poorer bearing capacity than expected. However thinking it over you will feel lucky to have found out at this early stage. Knowing the subsoil characteristics you can allow for this in your road construction and achieve the required strength and service life of the road and avoid future traffic inconveniences and expensive long-term maintenance.

Thinking green, we all benefit from building roads in the correct way from the very beginning.

Does it really matter what lies beneath the pavement?
Yes, let us have a look at the two examples below. They show calculations on a close to world-wide typical road structure:

sub-base (30 cm sand)
base course (20 cm gravel)
pavement (10 cm asphalt)

The only difference between the two examples is: In example A the subsoil has a bearing capacity of 45 MPa and in example B the bearing capacity is only 20 MPa.

You see a substantial decrease in the final surface bearing capacity!!

E0 of the final structure dropping from 218 MPa down to 147 MPa - a decrease of approx. 30%!

Examplesa B 1

How to respond to an unexpected low bearing capacity depends on the situation. You could choose to install a geo-grid or you could perform a lime or cement stabilisation depending on the soil. In either case you can use the PRIMA 100 LWD to check whether the reinforcement process fulfilled your expectations.

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PRIMA Subsoil 226


Bjarne Bylov Jensen
Bjarne Bylov Jensen
Head of PMC Sale & Market Department
+45 8228 1435


Finn Iversen
Finn Iversen
Support Manager LWD
+45 8228 1494