<p><p><h2>Preferred QC/QA Procedures</h2>The Federal Highway Administration (FHWA) does not provide any QC/QA guidance for this technology. Webster (1979), Al-Qadi and Hughes (2000), EN ISO 13426-1:2003(E), Emersleben and Meyer (2008), Pokharel (2010), Yang (2010), Han et al. (2011), and Thakur (2011) provided some QC/QA guidance for this technology.</p><p>There are different QC/QA methods necessary to ensure a proper construction, installation, and placement of geocell and infill materials in pavement systems. The proper methods are 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 geocell confinement in pavement systems 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-1961'><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 >•Surface course, base course, and subgrade: CBR, moisture content, swell and shrink potential, soil classification, grain size distribution, compaction, undrained shear strength, stiffness.
•Geotextile properties: grab tensile strength, grab elongation, tear strength, puncture strength, permittivity, UV radiation stability, transmissivity, percent open area, bond strength, sewn seam strength, apparent opening size, thickness, density, mass per unit area etc.
•Geocell properties: tensile strength, elongation, UV radiation stability, creep resistance property, creep reduction factor, elastic modulus, interface shear strength, etc
</td></tr><tr><td ><center>QC</td><td ><center>Process Control</td><td >•Installation of geocell, connection of geocell, number of lifts, lift thickness, passes and rolling pattern for compaction
</td></tr><tr><td ><center>QA</td><td ><center>Material Related</td><td >•Sand cone density test, vane shear test, nuclear gage test, DCP test
</td></tr><tr><td ><center>QA</td><td ><center>Process Control</td><td >•Roadway distress evaluation, FWD tests, laboratory tests</td></tr></tbody></table><br><h3>TABLE 2. PERFORMANCE CRITERIA USE IN QC/QA MONITORING PROGRAMS</h3><table class='tablepress' id='tablepress-1962'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Parameters</td><td >•CBR, moisture content, 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-1963'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Related</td><td >•Geocell confinement test, geocell welding test, creep test of geocell-confined soil, moisture distribution</td></tr><tr><td ><center>Process Control</td><td >•Intelligent compaction, FWD systems</td></tr></tbody></table></p></p>
<p><p><h2>QC/QA Guidelines</h2>Al-Qadi and Hughes (2000) and Emersleben and Meyer (2008) conducted FWD tests and data were analyzed to evaluate structural performance of the reconstructed geocell-reinforced road. Pokharel (2010), Thakur (2011), and Yang (2010) conducted laboratory plate loading tests to evaluate and verify the benefits of the geocell confinement effect. Emersleben and Meyer (2008) conducted plate loading tests on both lab and field to verify the benefits of geocell confinement effect. Han et al. (2011) and Pokharel (2010) conducted vane shear, DCP, and sand cone tests to verify the quality of subgrade and base course layers and also exhumed the tests sections after each test to examine deformed profiles of the subgrade and geocells. In addition, Han et al. (2011) also conducted nuclear gage tests to monitor the level of compaction and density measurement during compaction. The effect of geocell was expressed in terms of the improvement factor. Han et al. (2011), Pokharel (2010), Webster (1979), and Yang (2010) conducted full-scale trafficking tests to evaluate rutting behavior of roadways. The performance of test sections was evaluated from measurements of rut depth and base course layer thickness in the channelized wheel path, cross-sectional profile of the road surface and the deformed geocell, and strain in the geocell, with a cumulative number of vehicle passes. EN ISO 13426-1:2003(E), Pokharel (2010), Thakur (2011), and Yang (2010) provided information about some tests and their results to evaluate geocell properties for quality control purposes.</p><p>The QC/QA procedures of geocells include testing for the geocell properties such as tensile strength, creep resistance property, elastic modulus, creep reduction factor etc. Monitoring of geocell installation procedures during construction is also required. Because the QC/QA procedures are so broad in nature, there are new techniques being developed and adopted.</p><p>Currently, some QC/QA procedures for geocell confinement in pavement systems are available, but additional research into QC/QA is advised in order to allow for a better evaluation of this technology. The potential for various other QC/QA procedures should be investigated.</p><p> </p></p>
<p><p><h2>References</h2>Al-Qadi, I.L. and Hughes, J.J. (2000). "Field evaluation of geocell use in flexible pavements." Transportation Research Record: Journal of Transportation Research Board, 1709, 26-35.</p><p>Emerslebn, A. and Meyer, N. (2008). “The use of geocells in road constructions over soft soil: vertical stress and falling weight deflectometer measurements.” EuroGeo4 paper number 132, 8p.</p><p>EN ISO 13426-1 (2003). “Geotextiles and geotextile-related products- strength of internal structural junctions, Part 1: Geocells.” 13 p.</p><p>Han, J., Pokharel, S.K., Yang, X., Manandhar, C., Leshchinsky, D., Halahmi, I., and Parsons, R.L. (2011). “Performance of geocell-reinforced RAP bases over weak subgrade under full-scale moving wheel loads.” ASCE Journal of Materials in Civil Engineering, accepted.</p><p>Pokharel, S.K. (2010). Experimental Study on Geocell-Reinforced Bases under Static and Dynamic Loadings. Ph.D. dissertation, CEAE Department, the University of Kansas.</p><p>Thakur, J.K. (2010). Experimental Study on Geocell-Reinforced Recycled Asphalt Pavement (RAP) Bases under Static and Cyclic Loadingss. M.S. Thesis, CEAE Department, the University of Kansas.</p><p>Webster, S.L. (1979a). Investigation of Beach Sand Trafficability Enhancement Using Sand-Grid Confinement and Membrane Reinforcement Concepts; Report 1, Sand Test Sections 1 and 2. Technical Report GL-79-20, Geotechnical Laboratory, US Army Corps of Engineers Waterways Experimentation Station, Vicksburg, MS.</p><p>Webster, S.L. (1979b). Investigation of Beach Sand Trafficability Enhancement Using Sand-Grid Confinement and Membrane Reinforcement Concepts; Report 2, Sand Test Sections 3 and 4. Technical Report GL-79-20, Geotechnical Laboratory, US Army Corps of Engineers Waterways Experimentation Station, Vicksburg, MS.</p><p>Yang, X. (2010). Numerical Analyses of Geocell-Reinforced Granular Soils under Static and Repeated Loads. Ph.D. dissertation, CEAE Department, the University of Kansas.<strong> </strong></p></p>