<p><p><strong>References:<br></strong><em>Mooney et al. (2010)<br>Newman and White (2008)<br>Peterson et al. (2006)<br>Rahman et al. (2008)<br>White and Thompson (2008)<br>White et al. (2005, 2006b, 2007a, 2007b, 2008a, 2008b, 2008c, 2008d, 2009a, 2009B, 2009c, 2010.)</em></p><p><strong>Method Summary</strong></p><p>Moisture and dry density tests can be performed using a variety of test methods, e.g., sand cone (ASTM D1556 or AASHTO T191), rubber balloon (ASTM D2167 or AASHTO T205), test pit sand replacement (ASTM D4914), test pit water replacement (ASTM D5030), nuclear gauges (ASTM D6938 or AASHTO T310), and drive cores (ASTM D2937). A field test requires a reference laboratory test (e.g., Proctor or relative density tests) to measure the in-situ relative compaction. Moisture content plays a key role in soil compaction for many materials and it is important to know the moisture content-applied energy-density relationship from laboratory testing to predict field compaction. Moisture and density tests are widely used in earthwork construction QC/QA practice.</p><p><strong> </strong><strong>Accuracy and Precision</strong></p><p>ASTM standards for sand cone, rubber balloon, test pit sand replacement, and test pit water replacement methods indicate that the precision could not be determined due to the nature of the test methods. Based on repeatability measurements from a single operator, ASTM D6938 reports a standard deviation for wet density measurements as 0.3 to 1.2 lb/ft³ and for moisture content as 0.3 to 0.5% depending on the soil type and test method used (direct transmission or back scatter). For all the test methods, the accuracy of the test methods was not reported as a standard reference value was not available for comparison.</p><p><strong> </strong><strong>Adequacy of Coverage</strong></p><p>The tests represent material characteristics within about 0.3 meters of the test surface. Typical earthwork specifications require one test per 1,000 to 10,000 yd³.</p><p><strong> </strong><strong>Implementation Requirements </strong></p><p>The operation requires some training and experience. Use of nuclear gauges pose regulatory constraints and require specialized training by the manufacturer and local environmental agencies.</p><p><strong> </strong><strong>General Comments</strong></p><p>Moisture-density testing is widely used in earthwork construction QC/QA practice. However, it has limitations especially on projects with oversized particles and variable fill material. Further, moisture-density tests are only surrogate measurements that cannot be easily related to strength and stiffness properties of soil (which are used in design). Soil stiffness/modulus properties are heavily influenced by the underlying layer support conditions. Results presented in literature (e.g., Mooney et al. 2010) indicate that for compaction layer with relatively homogenous and stiff underlying layer, dry density measurements can be related well with CCC measurements. For heterogeneous underlying layer conditions, good correlations cannot be obtained. Some results in literature (White and Thompson 2008) demonstrated that moisture plays a role in correlations between density and CCC measurements.</p></p>