<p><p><strong>References:<br></strong><em>Aldridge and Naguib (1992)<br>ALLU (2007)<br>Garbin and Mann (2010)<br>Garbin et al. (2011)<br>Hayward Baker Inc. (2009)<br>Jelisic and Leppanen (1999)</em></p><p><strong>Method Summary</strong></p><p>Cone penetration tests (CPT) or piezometric cone penetration tests (CPTu) (ASTM D5778 and ASTM D6067) may be used to evaluate the shear strength and pore pressure response of the treated volume. Cone penetration testing provides continuous data measurements along the depth of penetration. Cone penetration testing is a quality assurance measure performed after mixing operations to verify that the specified level of improvement, e.g., strength, was achieved. By comparing profiles across the treated area, the homogeneity of the treated volume can be assessed.</p><p><strong>Accuracy and Precision</strong></p><p>Cone penetration tests provide continuous profiles along the depth of testing. Because of its small cross-sectional area, the CPT may yield erratic results as it passes through small unmixed inclusions, alternating between the resistance of improved soil and the low strength of the unimproved inclusion. If CPT tests are used, results should be carefully interpreted.</p><p><strong>Adequacy of Coverage</strong></p><p>Adequate coverage from cone penetration tests depends on the number of tests performed relative to the area of improvement. Engineering judgment should be used when determining the number of tests performed so that the coverage is adequate. The size of the area to be treated, variability in subsurface conditions, and the type and performance expectations of the proposed facility should be considered when determining testing frequency. Garbin and Mann (2010) suggest one test per 2,500 sq. ft. of improved area for the column penetration test (KPS). Similar criteria are appropriate for CPT as well. Closer spacing may be required if test results appear to be highly variable, even if specifications are met, or if homogeneity of the mix is in question.</p><p><strong>Implementation Requirements</strong></p><p>Cone penetrometers and CPT rigs are typical geotechnical engineering equipment. Equipment and experienced operators are readily available.</p><p><strong>General Comments</strong></p><p>The established history of the CPT makes it a good option for QC/QA testing. It provides continuous measurements along its depth of penetration. CPTs provide results that correlate well to soil strength. Though sometimes yielding erratic results, the CPT can be valuable in treated soils when the post-treatment shear strength is high enough that the column penetration test (KPS) vane meets refusal, as discussed in the next section. The CPT may meet refusal at high<br>shear strengths as well.</p></p>