<p><p><strong>Reference(s):</strong></p><p><em>Qubain et al. (2006)</em></p><p><strong>Method Summary</strong></p><p>Dynamic Cone Penetrometer (DCP) tests are used to assess the compaction improvement depth by comparing before and after stabilization results. DCP is generally used in a pavement foundation layer construction QA process and can measure soil properties up to about 2 meters. Difficulties with these test procedures are documented in the literature. Some examples include large particles or boulders encountered in the subsurface.</p><p>The DCP test method is described in ASTM D6951. The DCP test method involves driving a cone tip into the soil by lifting an 8 kg sliding hammer to a 575 mm drop height and then releasing it. The total penetration for a given number of blows is then measured and recorded as mm/blow (penetration resistance). ASTM D6951 provides correlations between California Bearing Ratio (CBR) and DCP results (mm/blow) for different soil types. Correlations between DCP and undrained shear strength and modulus are documented in the literature (e.g., White et al. 2009).</p><p><strong>Accuracy and Precision</strong></p><p>For subsurface conditions with large boulders or rocks, testing may be difficult. ASTM D6951 indicates that the repeatability standard deviation of the DCP test is less than 2 mm/blow.</p><p><strong>Adequacy of Coverage</strong></p><p>Sufficient evaluation requires many tests. The number of tests depends on the variability in subsurface conditions. Penetration tests are advantageous in assessing improvement in soil properties to greater depths than other surface tests (e.g., static and dynamic plate load tests).</p><p><strong>Implementation Requirements </strong></p><p>Some experience and special equipment is necessary. DCP tests can be performed by one or two people.</p><p><strong>General Comments</strong></p><p>Empirical correlations can be used to relate results from the penetration tests to soil engineering properties (e.g., soil strength, bearing capacity, stiffness/modulus, liquefaction susceptibility, etc.). These test methods are useful for QA. These methods can also be used for QC to assess improvements in subsurface conditions with increasing passes.</p></p>