<p><p><strong>References:<br></strong><em>Mooney et al. (2010)<br>Vennapusa et al. (2011)<br>White and Thompson (2008)<br>White et al. (2005, 2006a, 2006b, 2007a, 2007b, 2008a, 2008b, 2008c, 2009a, 2009b, 2009c, 2010)</em></p><p><strong>Method Summary</strong></p><p>Static Cone Penetration Tests (CPT) and Dynamic Cone Penetration (DCP) fall under this category. These tests have been used to assess soil shear strength properties or stiffness/modulus in compacted earth fill in comparison with roller-integrated compaction measurements. CPT is widely used in geotechnical applications and can measure soil properties to great depths (&gt;30 meters), while DCP is generally used in pavement foundation layer construction QA process and can measure soil properties up to 2 meters. These procedures may have difficulties with penetration when large particles or boulders are encountered in the subsurface.</p><p>CPT is described in ASTM D3441. CPT involves pushing an instrumented cone tip into the ground at a controlled rate and recording the sleeve friction and tip resistance of the cone almost continuously (about every 2 cm). Some modern electronic CPT cones now employ a pressure transducer to record pore water pressure data and is commonly referred to as CPTU method. The sleeve friction and tip resistance values have been correlated to soil classification and elastic modulus in the literature. One disadvantage of CPT is that it requires specialized equipment and personnel, and is more time consuming than DCP.</p><p>DCP test method is described in ASTM D6951. DCP test method involves driving a cone tip into the soil by lifting an 8 kg sliding hammer to 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. ASTM D6951 provides correlations between California Bearing Ratio (CBR) and mm/blow for different soil types. Correlations between DCP and undrained shear strength and modulus are documented in the literature.</p><p>Many case studies have documented correlations between CBR determined from DCP (for the compaction layer thickness) and roller-integrated compaction measurements. The correlations were sometimes relatively strong and sometimes were relatively weak (as assessed by coefficient of determination R² value). Of the many other factors that can contribute to scatter in correlation analysis, heterogeneity in the underlying layers is identified as a major factor that contributes to weak correlations (see Mooney et al. 2010). However, penetration tests are effective in detecting deeper “weak” areas (at depths &gt; 300 mm) that are commonly identified by the roller-integrated compaction measurements.</p><p><strong>Accuracy and Precision</strong></p><p>Accuracy of these test methods is hard to determine. ASTM D6951 indicates that the repeatability standard deviation of the DCP test is less than 2 mm/blow. Accuracy and precision of CPT tests are not reported in ASTM D3441. Gui et al. (1998) reported that for CPT tests conducted by different laboratories on same soil a variation of about ±10% has been reported in the literature.</p><p><strong> </strong><strong>Adequacy of Coverage</strong></p><p>Sufficient spatial coverage of these tests to adequately characterize the spatial variability requires many tests and the number of tests depends on the observed variability. Penetration tests are advantageous in assessing variations in soil properties vertically to greater depths than other tests, which primarily indicate the properties at the surface (e.g., density and static and dynamic plate load tests). DCP tests are more economical than CPT, but can only measure soil properties to a depth of about 1 meter, and up to 2 meters with extension rods.</p><p><strong>Implementation Requirements </strong></p><p>The DCP test can be run by one or two persons and requires minimal training. CPT requires specialized equipment and personnel with adequate training.</p><p><strong>General Comments</strong></p><p>There are many published empirical correlations that relate results from penetration tests to soil engineering properties (e.g., soil strength, bearing capacity, stiffness/modulus, liquefaction susceptibility, etc.). Results from DCP have been correlated to CCC measurements. These tests can serve as good QA measurements.</p></p>