<p><p><h2>Preferred QC/QA Procedures</h2>The Federal Highway Administration (FHWA) provides QC/QA guidance for this technology. The documents are summarized below. The document <em>Geotechnical Aspects of Pavements</em> is not specific to geosynthetic reinforcement; however it gives a thorough discussion of QC/QA procedures for pavement systems.</p><p><table class='tablepress' id='tablepress-1973'><thead><th><center>Publication Title</th><th><center>Publication
Year
</th><th><center>Publication Number</th><th><center>Available for Download</th></thead><tbody><tr><td ><center>Geotechnical Aspects of Pavements</td><td ><center>2010</td><td ><center>FHWA NHI-10-092</td><td ><center>Yes<sup>1</td></tr><tr><td ><center>Geosynthetic Design & Construction Guidelines – Reference Manual</td><td > <center>2008</td><td > <center>FHWA NHI-07-092</td><td > <center>No<sup>2</td></tr></tbody></table><br><p class="disclaimer"><sup>1</sup><a href="https://www.nhi.fhwa.dot.gov/training/nhistoresearchresults.aspx?get=&a… class="disclaimer"><sup>2</sup> <a href="http://www.nhi.fhwa.dot.gov/training/nhistore.aspx">http://www.nhi.fhwa… procedures are also included in the AASHTO (2001) <em>Geosynthetic Reinforcement of the Aggregate Base Course of Flexible Pavement Structures – PP 46-01</em>.</p><p>There are many QC/QA methods necessary to ensure a proper construction of a geosynthetic-reinforced pavement system. The proper methods will be dependent on the design methods, existing conditions, and desired performance. The majority of the QC/QA procedures are tests that are well defined by ASTM and AASHTO and non-proprietary.</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 Geosynthetic Reinforcement of Pavements are listed in Tables 1, 2, and 3. The entries in the tables 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-1974'><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 >•Base course and subgrade soil properties: CBR, permeability, moisture content, and grain size distribution
•Geosynthetic properties: chemical composition of geosynthetic fiber, grab strength, sewn seam strength, tear strength, puncture strength, permittivity, apparent opening size, and UV stability (retained strength)
</td></tr><tr><td ><center>QC</td><td ><center>Process Control</td><td >•Labeling, shipment, and storage, placement of a geosynthetic, placement and compaction of a base coarse, width of geosynthetic overlap or seam, and minimum aggregate thickness above geosynthetics
</td></tr><tr><td ><center>QA</td><td ><center>Material Related</td><td >•Moisture content, grain size distribution, pocket penetrometer, torvane, and nuclear densimeter tests</td></tr><tr><td ><center>QA</td><td ><center>Process Control</td><td >•Field observation (e.g., rutting)
</td></tr></tbody></table><br><h3>TABLE 2. PERFORMANCE CRITERIA USE IN QC/QA MONITORING PROGRAMS<strong> </strong></h3><table class='tablepress' id='tablepress-1975'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Parameters</td><td >•CBR, resilient modulus, relative compaction
</td></tr><tr><td ><center>System Behavior</td><td >•Roughness, International Roughness Index, present serviceability index, rut depth, fatigue cracking</td></tr></tbody></table><br><h3>TABLE 3. EMERGING QC/QA PROCEDURES AND MEASUREMENT ITEMS</h3><table class='tablepress' id='tablepress-1976'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Related</td><td >•Geosynthetic-Soil Resilient Interface Shear Stiffness (ASTM D7499, Test Method for Measuring Geosynthetic-Soil Resilient Interface Shear Stiffness); Modified wide-width tensile tests for cyclic loading and anisotropic geosynthetic properties (ASTM D7556 - 10 Standard Test Methods for Determining Small-Strain Tensile Properties of Geogrids and Geotextiles by In-Air Cyclic Tension Tests), Biaxial Load Strain Behavior of Geosynthetics (McGown and Kupec 2004); Alternative methods of determining Modulus of Resilience (Hillbrich, 2007)</td></tr><tr><td ><center>Process Control</td><td >•Intelligent Compaction, Instrumented Geosynthetics</td></tr></tbody></table></p></p>
<p><p><h2>QC/QA Guidelines</h2>Geosynthetic reinforcement in pavement systems is a technology that is a collection of design processes and construction methods. Because of the number of design processes, the QC/QA procedures for geosynthetic reinforcement in pavement systems can be vast and vary greatly depending on the existing conditions and design criteria. Each layer of the pavement system (subgrade, subbase, base course, and Hot Mix Asphalt [HMA]) must be tested and monitored to ensure that the specified design criteria and inputs are met.</p><p>In addition to monitoring the soil and wearing surface in unreinforced and reinforced conditions, the geosynthetics in a reinforced condition must also be monitored. The QC/QA procedures of geosynthetics include testing for the geosynthetic properties, such as tensile tests, puncture tests, apparent opening size, and mass per unit area. Monitoring installation procedures of the geosynthetic on the project is also required.</p><p>Currently there is a transition from the Empirical Design Method to the Mechanistic-Empirical Design Method (NCHRP 1-37A). The Mechanistic-Empirical Design Method allows for a more detailed analysis of loads, materials, environmental conditions, and response of the pavement system. The Mechanistic-Empirical Design Method also requires more input data and QC/QA procedures. The interaction properties of the geosynthetic and the soil along with the anisotropic properties of the geosynthetic become important measured properties and require new tests for geosynthetic properties.</p><p>Because the QC/QA procedures are so broad in nature, there are many new techniques being developed and adopted. New techniques include lasers, ground penetrating radar, intelligent compaction, and instrumented geosynthetics.</p><p>The SHRP2 QC/QA procedure documents, from this website, for mechanical stabilization of subgrades and bases, geosynthetic separation in pavement systems, geosynthetics in pavement drainage, and partial encapsulation should also be reviewed as these technologies are often used in combination with geosynthetic reinforcement.</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></p></p>
<p><p><h2>References</h2>AASHTO. (1997) “Standard Specifications for Geotextiles - M 288, Standard Specifications for Transportation Materials and Methods of Sampling and Testing.” 18<sup>th</sup> Edition, American Association of State Transportation and Highway Officials, Washington, DC.</p><p>AASHTO. (2001). “Geosynthetic Reinforcement of the Aggregate Base Course of Flexible Pavement Structures – PP 46-01” Standard Specifications for Transportation Materials and Methods of Sampling and Testing, 26<sup>th</sup> Edition, and Provisional Standards, American Association of State Transportation and Highway Officials, Washington, DC.</p><p>Al-Qadi, I., Brandon, T.L., and Bhutta, S.A. (1996). “Field evaluation of geosynthetically stabilized pavements.” Materials for the New Millennium: Proceedings of the Fourth Materials engineering Conference, Washington, DC, pp. 10-14.</p><p>Al-Qadi, I.L., Tutumluer, E., and Dessouky, S. (2006). “Construction and instrumentation of full-scale geogrid-reinforced flexible pavement test sections.” Airfield and Highway Pavements Specialty Conference, Atlanta, GA, pp 131-142.</p><p>Anderson, P. and Killeavy, M. (1989). “Geotextiles and geogrids: cost effective alternate materials for pavement design and construction.” Proceeding of Geosynthetics ’89, IFAI, Vol. 2, San Diego, California, pp. 353-360.</p><p>Berg, R.R., Christopher, B.R., and Perkins, S. (2000). “Geosynthetic reinforcement of the aggregate base/subbase courses of pavement structures.” GMA White Paper ΙΙ, Prepared for the AASHTO Committee 4E, 176p.</p><p>Collin, J.G., Kinney, T.C., and Fu, X. (1996). “Full scale highway load test of flexible pavement systems with geogrid reinforced base course.” Geosynthetics International, Vol. 3, No. 4, pp. 537-549.</p><p>Collins, B.M., Mahoney, J.P., and Holtz, R.D. (2005). “FWD analysis of pavement sections with geotextile separators.” Proceedings of the Geo-Frontiers 2005 Conference, Geotechnical Special Publication 130 (CD-ROM), ASCE.</p><p>Christopher, B.R., Schwartz, C., and Boudreau, R. (2010). “Geotechnical Aspects of Pavements,” FHWA-NHI-10-092, Federal Highway Administration, Washington, DC, 568p.</p><p><a href="https://www.nhi.fhwa.dot.gov/training/nhistoresearchresults.aspx?get=&a…, E.V., Perkins, S.W., and Ganeshan, S.K. (2005). “Determining geosynthetic material properties to reinforced pavement design.” Conference Geo-Frontiers, Geotechnical Special Publication 130, Advances in Pavement Engineering, ASCE, Austin, TX.</p><p>Holder, W.H. and Andrease, J. (2004). “Geogrid reinforcement to reduce pavement section thickness: a case study.” Geotechnical Special Publication: Geotechnical Engineering for Transportation Projects, pp. 1006-1013</p><p>Holtz, R.D., Christopher, B.R., and Berg, R.R. (2008). “Geosynthetic design and construction guidelines.” Report No. FHWA-NHI-07-092, U.S. Department of Transportation, National Highway Institute, Federal Highway Administration, Washington, DC.</p><p>Huntington, G. and Ksaibati, K., (1999), “Evaluation of Geogrid-Reinforced Granular Base,” <em>Geotechnical Special Publication No. 89, Recent Advances in the Characterization of Transportation Geo-Materials</em>, ASCE, pp. 13-24.</p><p>Montanelli, F., Zhao, A., and Rimoldi, P. (1997). “Geosynthetic-reinforced pavement system: testing and design.” In: Proceedings of Geosynthetics ’97, IFAI, Vol. 2, Long Beach, CA, pp. 619-632.</p><p>Perkins, S.W. and Edens, M.Q. (2002). "Finite Element and Distress Models for Geosynthetic-reinforced Pavements." International Journal of Pavement Engineering, 3(4): 239-250.</p><p>Perkins, S.W., B. R. Christopher, B.R., Lacina, B.A., and Klopmaker, J. (2009). "A mechanistic-empirical model for base-reinforced flexible pavements." Int. J. Pavement Eng. International Journal of Pavement Engineering, 10(2): 101-114.</p><p>Perkins, S.W. (1999). “Geosynthetic reinforcement of flexible pavements: laboratory based pavement test sections.” Report No. FHWA/MT-99-001/8138, Prepared for the State of Montana Department of Transportation Research, Development and Technology Transfer Program in cooperation with the U.S. Department of Transportation Federal Highway Administration, Bozeman, MT.</p><p>Webster, S.L. (1993). “Geogrid reinforced base course for flexible pavements for light aircraft, test section construction, behavior under traffic, laboratory tests, and design criteria.” Technical Report GL-93-6, U.S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg, MS, 86p.</p></p>