<p><p><strong>References:<br></strong><em>ALLU (2007)<br>ASTM D2573<br>Bredenberg et al. (1999)<br>Forsman et al. (2008)<br>Havukainen et al. (2011)<br>Jelisic and Leppanen (2003)</em></p><p><strong>Method Summary</strong></p><p>The vane shear test and the column vane shear test provide values for undrained shear strength. These in situ shear tests are quality assurance measures performed after mixing operations to verify that the specified level of improvement has been achieved. The column vane (also called the Finnish vane) shear test differs from the conventional vane shear test apparatus in that its vanes are different in geometry and in thickness, making it more suitable for the higher shear strength encountered when testing shallow-mixed or mass-stabilized soil. The shaft of the vane may also have a sleeve to reduce or measure shaft friction. Although an oversized drill hole is used to insert the vane, this is often not critical to the accuracy of the test. The vane is pushed into the treated soil volume and rotated at the depth of interest. The moment or torque required to shear the treated soil to failure is converted to a shear strength. The results of multiple tests can be used to calibrate the results of cone penetration tests and column penetration tests (i.e. determine a more accurate bearing capacity factor).</p><p><strong>Accuracy and Precision</strong></p><p>The accuracy and precision of vane tests is dependent on adherence to the standard test procedure.</p><p><strong>Adequacy of Coverage</strong></p><p>Vane tests only evaluate the local shear strength. Multiple tests, at the judgment of the engineer, should be performed to adequately characterize the area of improvement. Vane shear and column vane shear tests are slower and thus more expensive than CPT or KPS and are not likely to be practical as a stand-alone QA measure. However, column vane and vane shear tests may be valuable calibration tools when used in conjunction with CPT or KPS to provide adequate characterization of the treated soil.</p><p><strong>Implementation Requirements</strong></p><p>Though vane tests are typical engineering tests, experience and specialized equipment are required. The column vane test is less typical than the traditional vane shear test.</p><p><strong>General Comments</strong></p><p>Vane shear and column vane tests are not used as often as other methods for shallow soil mixing and mass stabilization. Because many soil mix materials are brittle, disturbance caused by installing the vane may significantly affect test results. Additionally, refusal may be a concern with high strength soils. The testing limits of the particular equipment used should be considered along with the anticipated shear strengths to determine the likelihood of meeting refusal and damaging the equipment. In many cases, the KPS using previously established bearing capacity factors may actually be more reliable than the vane shear test.</p></p>