<p><p><strong>References:<br></strong><em>Aldridge and Naguib (1992)<br>Garbin et al. (2011)</em></p><p><strong>Method Summary</strong></p><p>Stability and homogeneity of the post-treatment soil can be assessed using test pits and partial excavation of mixed elements. Test excavation is a quality assurance technique used to verify the extent of mixing and homogeneity of the mixed soil. Portions of the soil volume or soil-mixed structure can be excavated and visually inspected to confirm integrity and homogeneity. Probes such as pocket penetrometer, push cone type probes, and portable vane shear devices can be used to evaluate uniformity in strength, and photos provide an excellent log of the quality of mixing. A hand held x-ray fluorescence analyzer, as discussed in the next section, could also be used along the sides or on samples removed from the test pit to provide an indication of the homogeneity of the soil mix. Infrared images of the test pit may provide additional information about mixing uniformity. Areas with more cement may be warmer than areas with less cement due to the heat of hydration of the binder material. Test pits are typically excavated 7 to 28 days after mixing.</p><p><strong>Accuracy and Precision</strong></p><p>Test excavation can be a useful observational quality assurance method. While accuracy and precision are not easily assigned, the quality of the observation likely depends on the experience of the inspector.</p><p><strong>Adequacy of Coverage</strong></p><p>Test excavations are only representative of the conditions at the excavation location, but test pits do expose a relatively large volume and surface area of treated ground. The number of excavations should be determined based on the judgment of the engineer based on the size of the area to be treated, variability in subsurface conditions, and the type and performance expectations of the proposed facility.</p><p><strong>Implementation Requirements</strong></p><p>Test excavations require only typical excavation equipment and an experienced inspector. Test pits will need to be backfilled after inspection. Test pits should be backfilled with material that exhibits the same behavior and properties of the undisturbed post-treatment soil volume. Proper compaction during backfilling and/or remixing with additional binder will be critical to obtain the required properties for replaced materials.</p><p><strong>General Comments</strong></p><p>Test pits allow a visual inspection of the treated soil. Even if the volume appears well-mixed and stable, the treated soil may not meet specified strengths, permeability, etc. Test pits should be accompanied by field and laboratory testing to verify design properties. It may not be possible to excavate test pits with conventional soil excavation equipment if the treated soil is too hard.</p></p>