Compaction testing on site is to monitor and control the earthworks compaction process by the contractor and is known as ‘end product testing’.

  • Our testing will help determine the compaction plant and methodology on site.
  • It will help in highlighting changes of material as a project proceeds generally via pass/fail criteria.

Compaction tests we offer:

  • DCP Test (Dynamic Cone Penetration)
  • Clegg test (Clegg Impact Soil Tester)

DCP test used on this new housing site to determine the strength of the underlying pavement layers.

The test involves raising and dropping the hammer to drive the cone on the lower shaft through the underlying pavement layers. After each hammer blow, the penetration of the cone is measured and recorded in stiffer soils, readings may be recorded after several hammer blows.

Test results taken in the field are put onto a spreadsheet to produce the DCP graph to determine the strength of the sub base and the structural properties of existing road pavements constructed of unbound materials. A CBR (California bearing ratio)  is calculated.

It is commonly used to determine a  (CBR) profile for pavement design.

The DPC is a simple, robust tool meaning it is easy to use, portable, and suitable to use in locations where access may be difficult.

Note, Whilst it is quick and easy the DCP test provides only an approximate assessment of CBR. 

The Clegg Impact Soil Tester is a compact and reliable instrument for monitoring and controlling the quality of reinstatements while the work is in progress, avoiding the need for re-excavation if later tests were to indicate poor workmanship.

The Clegg test is a particularly useful tool to check the performance of trench filling operations and compaction levels of materials, this could result in  penalties on undertakers who fail to meet the specified standards in the NRSWA and SROH.

Objectives of compaction testing by Trench Right:


  • Quality control of reinstated backfills
  • Layer thickness monitoring
  • Trench or excavation backfill compaction
  • Compaction homogeneity
  • Compaction control of all types of embankments (roads, rail, earthworks, dams, dykes, etc)
  • Standard DCP is a recognised method for measuring in situ strength of flexible road construction in all materials other than bound concrete or bituminous mixtures.