<p><p><strong>References:<br></strong><em>Aldridge and Naguib (1992)<br>ALLU (2007)<br>Burke et al. (2007)<br>Garbin and Mann (2010)<br>Garbin et al. (2011)<br>Hayward Baker Inc. (2009)</em></p><p><strong>Method Summary</strong></p><p>Active construction monitoring refers to the observation of construction processes and recordingcof important data to ensure that they are being performed according to project requirements, and consistently applied. Construction monitoring is primarily a quality control measure taken by the contractor to ensure that the mixing operation is being performed according to the contractor’s reviewed and approved construction quality control plan. Observations by the engineer or owner’s representative may be considered a quality assurance measure. The observations and documentation may be reviewed in conjunction with post-mixing test results and the QC plan to determine whether the level of improvement was achieved. Several aspects of an SSM or MS project require careful monitoring:<br><ul> <li> Treatment geometry (area, depth, spacing, etc.)</li> <li>Mixing tool rotation rate</li> <li>Mixing energy</li> <li>Number of passes</li> <li>Binder dosage</li></ul>During mass mixing projects, mixing energy and binder dosage can be monitored using electronic data acquisition systems. Flow meters should be used, monitored, and recorded when electronic data acquisition systems are not available or applicable. The geometry should be carefully controlled and documented by the contractor and monitored by the owner’s representative to ensure that treatment is being performed within the correct boundaries (or at the correct spacing for SSM) and to the correct depth and top elevation.</p><p><strong>Accuracy and Precision</strong></p><p>Observation does not provide a direct measure of performance and therefore cannot easily be assigned a level of accuracy. Good observation can indicate construction quality and how closely the specification requirements and the contractor’s approved quality control plan were followed.</p><p><strong>Adequacy of Coverage</strong></p><p>Careful observation should be made throughout the construction process at all locations across the project site. In this case, the level of coverage should be complete to provide an idea of the quality of construction for the entire project.</p><p><strong>Implementation Requirements</strong></p><p>Construction monitoring requires a proactive inspector with knowledge of the materials and procedures used as part of shallow soil mixing or mass stabilization. Monitoring of pneumatically-delivered or pumped binder, as well as rotation rates and penetration/withdrawal rates requires electronic systems, which are often part of the construction equipment package.</p><p><strong>General Comments</strong></p><p>Active construction monitoring is the most important QC/QA procedure for shallow soil mixing and mass stabilization projects. Success of the project requires that design specifications be adhered to carefully and that mixing be performed thoroughly and at sufficient rates and times.</p></p>