<p><p><h2>Preferred QC/QA Procedures</h2>There is no FHWA recommended method for Bulk Infill Grouting QC/QA. QC/QA methods are not proprietary.</p><p>QC procedures refer to the properties of the grout being injected into the subsurface voids (e.g., fluidity), the adequacy (i.e., level of penetration) of the infilling, and the process control. QA procedures refer to the properties of the grout following hardening in the subsurface voids (e.g., unconfined compressive strength) and the adequacy of the infilling.</p><p>Refer to Chuaqui and Bruce (2003), Schaefer et al. (2016), Holmquist et al. (2003), Millet and Engelhardt (1982), Müller and Bruce (2000), Ohio Department of Transportation (1998), Woodward (2005) for more information of QC/QA procedures.</p><p>Construction quality is achieved by meeting established requirements, as detailed in project plans and specifications, including applicable codes and standards. Quality Control (QC) and Quality Assurance (QA) are terms applied to the procedures, measurements, and observations used to ensure that construction satisfies the requirements in the project plans and specifications. QC and QA are often misunderstood and used interchangeably. Herein, Quality Control refers to procedures, measurements, and observations used by the contractor to monitor and control the construction quality such that all applicable requirements are satisfied. Quality Assurance refers to measurements and observations by the owner or the owner's engineer to provide assurance to the owner that the facility has been constructed in accordance with the plans and specifications.</p><p>The components of QC/QA monitoring programs for Bulk Infill Grouting are listed in Tables 1, 2, and 3. The entries in the table are a list of typical items, not a list of all methods that could be used for QC/QA. Some QC procedures and measurement items may also serve as QA procedures and measurement items.<br><h3><strong>TABLE 1. TYPICAL EXISTING QC/QA PROCEDURES AND MEASUREMENT ITEMS</strong></h3><table class='tablepress' id='tablepress-1924'><thead><th><center>QC or QA</th><th><center>Material or Process</th><th><center>Items</th></thead><tbody><tr><td ><center>QC</td><td ><center>Material Related</td><td >•Field Quality Control Tests for Grout Mixes
•Borehole Cameras
•Verification Drilling
</td></tr><tr><td ><center>QC</td><td ><center>Process Control</td><td >•Grouting Matrix
</td></tr><tr><td ><center>QA</td><td ><center>Material Related</td><td >•Field Quality Control Tests for Grout Mixes
•Verification Drilling
•Coring
•Geophysical Tests
</td></tr><tr><td ><center>QA</td><td ><center>Process Control</td><td >•Grouting Matrix
</td></tr></tbody></table><br><h3><strong>TABLE 2. PERFORMANCE CRITERIA USE IN QC/QA MONITORING PROGRAMS </strong></h3><table class='tablepress' id='tablepress-1925'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Parameters</td><td >•Grout Rheology
•Grout Strength
</td></tr><tr><td ><center>System Behavior</td><td >•Adequacy of Grout Penetration
</td></tr></tbody></table><br><h3><strong>TABLE 3. EMERGING QC/QA PROCEDURES AND MEASUREMENT ITEMS</strong></h3><table class='tablepress' id='tablepress-1926'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Related</td><td >•None noted</td></tr><tr><td ><center>Process Control</td><td >•None noted</td></tr></tbody></table></p></p>
<p><p><h2>QC/QA Guidelines</h2>With respect to the properties of the grout, the QC procedures associated with Bulk Infill Grouting are exactly similar to the QC procedures associated with conventional grouting techniques. Bulk Infill Grouting, however, relies upon other QC techniques as well including verification drilling and coring in order to evaluate the adequacy of the grout penetration. The same QC procedures for evaluating the adequacy of grout penetration can be applied as QA procedures. Despite the existence of the various QA techniques, few case histories actually employ QA procedures. In these instances, the verification of the success of Bulk Infill Grouting is limited to whether or not the subsidence has been mitigated years after grouting was implemented.</p><p>Inspections, construction observations, daily logs, and record keeping are essential QC/QA activities for all technologies. These activities help to ensure and/or verify that:<br><ul> <li>Good construction practices and the project specifications are followed.</li> <li>Problems can be anticipated before they occur, in some cases.</li> <li>Problems that do arise are caught early, and their cause can oftentimes be identified.</li> <li>All parties are in good communication.</li> <li>The project stays on schedule.</li></ul>Additional technology-specific details for inspections, construction observations, daily logs, and record keeping QC/QA activities are provided in the <em>Individual QC/QA Methods </em>section below.</p><p> </p></p>
<p><p><h2>References</h2>Chuaqui, M. and Bruce, D.A. (2003). “Mix Design and Quality Control Procedures for High Mobility Cement Based Grouts.” Grouting and Ground Treatment, Proceedings of the Third International Conference, Geotechnical Special Publication No. 120. Edited by L.F. Johnsen, D.A. Bruce, and M.J. Byle, American Society of Civil Engineer, New Orleans, LA, February 10-12, pp. 1153-1168.</p><p>Holmquist, D.V., Thomas, D.B. and Simon, K. (2003). “Subsidence Mitigation Using Void Fill Grouting.” ASCE Geotechnical Special Publication No. 120: Grouting and Ground Treatment, 1103-1114.</p><p>Millet R.A and Engelhardt R.L. (1982). “Matrix Evaluation of Structural Grouting of Rock.” Proceedings of the Conference on Grouting in Geotechnical Engineering, New Orleans, Louisiana, 753-768.</p><p>Müller, R. and Bruce, D.A. (2000). “Equipment for Cement Grouting: An Overview.” ASCE Geotechnical Special Publication No. 104: Advances in Grouting and Ground Modification, 155-172.</p><p>Ohio Department of Transportation. (1998). “Manual for Abandoned Underground Mine Inventory and Risk Assessment.” May 15.</p><p>Schaefer, V.R., Berg, R.R., Collin, J.G., Christopher, B.R., DiMaggio, J.A., Filz, G.M., Bruce, D.A., and Ayala, D. (2016). “Ground Modification Methods,” Federal Highway Administration, Washington, DC, FHWA NHI-16-028 (Vol. II), 542p.</p><p><a href="https://www.fhwa.dot.gov/engineering/geotech/pubs/nhi16028.pdf">https:/…, J. (2005). An Introduction to Geotechnical Processes. Glasgow, Scotland: Bell & Bain Ltd.</p><p> </p></p>