The Dynamic Cone Penetrometer (DCP) Supplied by Laboratory Equipment Supplies is an instrument designed for the rapid in-situ measurement of the structural properties of existing road pavements constructed of unbound materials. The robust and simple design means that the DCP is quick and easy to use, portable and suitable for use in locations where access may be difficult.

Correlations have been established between measurements with the DCP and conventional in-situ CBR so that results can be interpreted and compared with CBR specifications for pavement design. A typical test takes only a few minutes and therefore the instrument provides a very efficient method of obtaining information which would normally require the digging of test pits.

Method of use

The 8 kg free fall hammer is lifted and dropped through a height of 575mm. The distance pf penetration of the cone tip is then recorded and the cycle repeated. Continuous measurements can be made down to a depth of approx 1000mm or when extension shafts are fitted to a maximum recommended depth of 2 metres. Where sub-pavement layers have different strengths, the boundries can be identified and the thickness determined.

The Basic CBR Test

The California Bearing Ratio, believe it or not, was developed by The California State Highways Department. It is in essence a simple penetration test developed to evaluate the strength of road subgrades.

This consists of causing a plunger of standard area to penetrate a soil sample, (this can be in the laboratory or on site). The force (load) required to cause the penetration is plotted against measured penetration, the readings noted at regular time intervals. This information is plotted on a standard graph, and the plot of the test data will establish the CBR result of the soil tested. 

Reason For CBR Test

It sounds complicated, but the basis behind it is quite simple. We are determining the resistance of the subgrade, (i.e. the layer of naturally occurring material upon which the road is built), to deformation under the load from vehicle wheels. Even more simply put, 'How strong is the ground upon which we are going to build the road'.

THE CBR TEST IS A WAY OF PUTTING A FIGURE ON THIS INHERENT STRENGTH, THE TEST IS DONE IN A STANDARD MANNER SO WE ARE ABLE TO COMPARE THE STRENGTHS OF DIFFERENT SUBGRADE MATERIALS, AND WE ARE ABLE TO USE THESE FIGURES AS A MEANS OF DESIGNING THE ROAD PAVEMENT REQUIRED FOR A PARTICULAR STRENGTH OF SUBGRADE.

The stronger the subgrade (the higher the CBR reading ) the less thick it is necessary to design and construct the road pavement, this gives a considerable cost saving.

We can also supply spares and repair your DCP.

Our basic dcp kit comes complete with everything needed for a 1 meter test. Supplied with spanners, allen key, weight & cone. (DCP test)

Optional dcp extension rod enables the testing depth to be extended by 1 meter.

  • 60° cone
  • 8kg weight
  • 575mm drop height
  • Testing depth to 1000mm
  • Extension rods available for depths up to 2 or even 3 meters
  • Portable and easy to operate
  • Tests can be carried out in minutes
  • Results correlate well with conventional CBR readings
  • Well proven, robust design