<p><p><strong>Reference(s):</strong></p><p><em>Christopher et al. (2010)</em></p><p><strong>Method Summary</strong></p><p>The DCP device consists of a steel shaft with a conical tip which is driven into the soil with either a 10 or 18 pound hammer. DCP testing typically allows the tip to be driven to a depth of 3 feet. The principle behind the DCP is that a direct correlation exists between the strength of a soil and its resistance to penetration by solid objects. The number of blows to drive the conical tip is recorded at approximate one-inch intervals during penetration such that a continuous profile of resistance to depth is developed. Correlations have been developed for different soil types based on the number of hammer blows per increment of advancement.</p><p><strong>Accuracy and Precision</strong></p><p>DCP testing has fair reliability. The test method is not considered precise because it requires the hammering of a probe into the ground.</p><p><strong>Adequacy of Coverage</strong></p><p>Although not a precise test, DCP testing provides an immediate assessment of the site conditions. DCP testing is also a fairly rapid test which allows assessment of large areas.</p><p><strong>Implementation Requirements </strong></p><p>Many transportation departments routinely use DCP testing.</p><p><strong>General Comments</strong></p><p>DCP testing can be utilized during construction of embankments, structures, and pavements to both identify the presence of unstable soils which require excavation and to assess the strength of the replacement materials.</p></p>