Typical DCP/TRL Probe
The Transvaal Roads Department in South Africa began using the DCP to investigate road pavement in 19733. Kleyn reported the relative results obtained using a 30° cone and a 60° cone. In 19824, Kleyn described another DCP design, which used a 60° cone tip, 8 kg (17.6 lb) hammer, and 575 mm (22.6 in) free fall. This design was then gradually adopted by countries around the globe including the USA and by Transport Research Laboratory (TRL) in the UK. In 2004, the ASTM D6951-03 Standard Test Method for Use of the Dynamic Cone Penetrometer in Shallow Pavement Applications described using a DCP with this latest design5.
DCP Procedure
provides alternative methods which must be considered by the Designer.
Historical Background
The 8 kg free fall hammer is manually lifted and dropped through a height of 575mm. The distance of penetration of the cone tip is then recorded and the cycle repeated. Continuous measurements The earliest can be made down to a technical depth of approximately references to the 850mm or when extension Dynamic Cone rods are fitted to a maximum Penetrometer (DCP) recommended depth of 2 metres. suggest that it was
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The earliest technical references to the Dynamic developed in 1959 by Cone Penetrometer (DCP) DCP testing consists of suggest that it was developed Professor George F. using the DCP’s free-falling in 1959 by Professor George hammer to strike the Sowers... F. Sowers, Professor of Civil cone, causing the cone to Engineering, Georgia institute penetrate the base or subgrade soil, and then of Technology, Atlanta, USA1. The original measuring the penetration per blow, also DCP used a 15 lb weight dropping over 20 ins called the penetration rate (PR), in mm/blow. and used a 40o cone. This DCP was originally This measurement denotes the stiffness of developed for field exploration and for the tested material, with a smaller PR number verifying individual footing foundations during indicating a stiffer material. In other words, the construction. The DCP was further developed PR is a measurement of the penetrability of in South Africa for the evaluation of in-situ the subgrade soil. pavement strength or stiffness of newly Technical Output from the DCP constructed roads in the 1960s. Dr. D. J. van Vuuren designed this version of the DCP with a The most common use of the Dynamic Cone 30° cone2. Penetrometer (DCP) is to provide a quick and
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