The Dynamic Cone Penetrometer (DCP) is a rapid and inexpensive device for characterizing unbound paving materials and subgrade soils. The DCP may be used to estimate the strength of these materials through the use of correlations with the California Bearing Ratio (CBR) and resilient modulus (Mr). The DCP, shown schematically in figure 1, consists of the following components: a 15.8-mm (5/8-in) diameter steel drive rod with a replaceable cone tip, an 8-kg (17.6-lb) weight or hammer which is dropped a fixed height of 575 mm (22.6 in), a coupler assembly, and a handle. The cone tip has an included angle of 60 degrees and a diameter at the base of the cone of 20 mm (0.79 in). The drive rod may be unmarked or graduated so that increments of 5.0 mm (0.2 in) may be determined. The apparatus is typically constructed of stainless steel, with the exception of the cone tip, which may be constructed from hardened tool steel or a similar material.