<p><p><h2>Preferred QC/QA Procedures</h2>Jet grouting has no standard Federal Highway Administration quality control and quality assurance methods, but several of the QC/QA procedures recommended here are included in the guide specification from the Geo-Institute Grouting Committee. Selection of particular QC/QA procedures for specific projects will depend on the project-specific conditions and objectives.</p><p>Several complementary QC/QA procedures may be implemented in the overall QC/QA plan. These include continuously recording the jetting parameters, sampling the grout slurry and the soilcrete spoil, measuring ground settlement and heave, taking wet-grab samples, coring completed columns, and performing location surveys of every column. Once the grouting has been completed, cone penetration tests can be performed to provide further validation that the columns have reached the target diameter. If additional proof of column geometry is needed, the tops of the columns can be exposed. Seismic surveys can be used to verify column geometry but are difficult to perform and the results are open to interpretation. Wave-based analysis of column geometry and density shows the potential for being an easy and inexpensive form of quality control but it is still in the developmental stages. The recommended sampling frequencies for several of the QC/QA procedures are listed below in the QC/QA Guidelines section.</p><p>The same QC/QA procedures that are implemented during production grouting should be used during a test grouting program. In addition, the top of every test column should be exposed to verify that the necessary column diameter can be achieved. Deeper exposure is important if the strata change.</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 jet 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>TABLE 1. TYPICAL EXISTING QC/QA PROCEDURES AND MEASUREMENT ITEMS</h3><table class='tablepress' id='tablepress-2001'><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 >• Verify correct jetting parameters
• Check materials and mixes
</td></tr><tr><td ><center>QC</td><td ><center>Process Control</td><td >•Verify column location and depth</td></tr><tr><td ><center>QA</td><td ><center>Material Related</td><td >• Determine soilcrete strength
</td></tr><tr><td ><center>QA</td><td ><center>Process Control</td><td >• Verify column geometry</td></tr></tbody></table><br><h3>TABLE 2. PERFORMANCE CRITERIA USE IN QC/QA MONITORING PROGRAMS</h3><table class='tablepress' id='tablepress-2002'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Parameters</td><td >•Verify homogeneous soilcrete throughout columns (compressive strength, permeability, density)</td></tr><tr><td ><center>System Behavior</td><td >•Ground settlement and heave measurements</td></tr></tbody></table><br><h3>TABLE 3. EMERGING QC/QA PROCEDURES AND MEASUREMENT ITEMS</h3><table class='tablepress' id='tablepress-2003'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Related</td><td >• Wave-based analysis of geometry and density</td></tr><tr><td ><center>Process Control</td><td >• None noted
</td></tr></tbody></table></p></p>
<p><p><h2>QC/QA Guidelines:</h2>The following test frequencies are recommended:</p><p>Wet grab sample frequency<br><ul> <li>One per column during test phase, two columns per week during production phase – Bruce et al. (2001)</li> <li>One round per day consisting of three samples from different depths in a single column. Each sample should be large enough to create four cylinders (3-inch diameter by 6-inch height) – Burke (2007a)</li></ul>Coring frequency<br><ul> <li>2 to 10% of columns cored during production – Geo-Institute (2009), Bruce et al. (2001)</li> <li>All columns during test phase – Meyers et al. (2004)</li></ul>Grout slurry sample frequency<br><ul> <li>One sample per day – Burke et al. (2000a)</li></ul>CPT frequency<br><ul> <li>On columns selected for CPT testing, four CPTs per column, located at 0.7, 1.0, 1.3, and 1.5 times the estimated radius – Burke et al. (2000a)</li></ul>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><h2>References</h2>Brill, G.T., Burke, G.K, Ringen, A.R. (2003). “A ten-year perspective of jet grouting; Advancements in applications and technology.” <em>Geotechnical Special Publication: Grouting and Ground Treatment</em>, 120, 218-235.</p><p>Bruce, D. A. (2007a). “Managing the design and construction of grouted cut-offs in emergency conditions.” <em>GeoDenver 2007, GSP-168: Grouting for Ground Improvement: Innovative Concepts and Applications</em><em>, </em>ASCE, Reston, VA.</p><p>Bruce, D. A. (2007b). “Pregrouting of tunnels in rock: The case for new thinking.” <em>GeoDenver 2007, GSP-168: Grouting for Ground Improvement: Innovative Concepts and Applications</em><em>,</em> ASCE, Reston, VA.</p><p>Bruce, D.A., S.T. Hague, and R. Hitt. (2001). “The Treatment by Jet Grouting of a Bridge Foundation on Karstic Limestone.” <em>Foundations and Ground Improvement, Proceedings of a Specialty Conference,</em> ASCE, Blacksburg, VA, June 9-13, Geotechnical Special Publication No. 113, pp. 145-159.</p><p>Burke, G. K. (2007a). “New methods for underpinning and earth retention.” <em>GeoDenver 2007, GSP-168: Grouting for Ground Improvement: Innovative Concepts and Applications</em><em>,</em> ASCE, Reston, VA.</p><p>Burke, G. K. (2007b). “Vertical and horizontal groundwater barriers using jet grout panels and columns.” <em>GeoDenver 2007, GSP-168: Grouting for Ground Improvement: Innovative Concepts and Applications,</em> ASCE, Reston, VA.</p><p>Burke, G.K., Cacoilo, D.M., and Chadwick, K.R. (2000b). “Superjet grouting: New technology for in situ soil improvement.” Transportation Research Record 1721, Paper No. 00-0665, 45-53.</p><p>Burke, G.K., Peterson, J.H., and Smith, M.L. (2000a). “Superjet grouting and the quality of its product.” <em>Geotechnical Special Publication- Grouting and Ground Modification</em>, 104, 111-125.</p><p>Gularte, F. B., Taylor, G. W., and Shao, L.S. (2007). “Observational monitoring methods for improved grouting and soil improvement.” <em>GeoDenver 2007, GSP-168: Grouting for Ground Improvement: Innovative Concepts and Applications,</em> ASCE, Reston, VA.</p><p>Kauschinger, L.J., Rachid, H., and Perry, E.B. (1992). “Methods to estimate composition of jet grout bodies,” <em>Proc. Grouting, Soil Improvement and Geosynthetics Conference</em>, ASCE, Reston, VA, Geotechnical Special Publication No. 30, pp. 194-205.</p><p>Maswoswe, J.J.G. (2003). “QA/QC for jet grouting in deep Boston blue clay central artery/tunnel project.” <em>Grouting and Ground Treatment</em>, 120, 236-247.</p><p>Meyers, J., Myers, T., and Petrasic, K. (2004). “Jet grout stabilization of steeply excavated soil slope.” <em>Grouting 2003</em>, 318-329.</p><p>Nicholson, P.J. and D.A. Bruce. (1996). "Jet Grouted Envelope for Soft Ground Tunnel," <em>Proc. of North American Tunneling ‘96,</em> Ed. by Ozdemir, A.A. Balkema, Rotterdam, pp. 395-400.</p><p>Schorr, C.-P., Traegner, R., and Micciche, R. J. (2007). “Evaluating in-situ jet grout column diameters utilizing wave analysis.” <em>GeoDenver 2007, GSP-168: Grouting for Ground Improvement: Innovative Concepts and Applications,</em> ASCE, Reston, VA.</p><p><strong> </strong></p></p>