<p><p><h2>Preferred QC/QA Procedure</h2>There is no FHWA QC/QA guidance related specifically to Fiber Reinforcement in Pavement Systems. However, the FHWA <em>Geotechnical Aspects of Pavements</em> document covers many of the QC/QA procedures for pavement systems reinforcement regardless of technologies used. The mechanical and chemical stabilization of subgrade and base courses technologies should also be reviewed, as these technologies are often used in conjunction with fiber reinforcement. Intelligent compaction technology should also be reviewed.</p><p><table class='tablepress' id='tablepress-1957'><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></tbody></table><br><p class="disclaimer"><sup>1</sup><a href="https://www.nhi.fhwa.dot.gov/training/nhistoresearchresults.aspx?get=&a… (1993) and AASHTO (2008) cover the empirical and the mechanistic-empirical design methods for flexible pavements.</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 fiber reinforcement in pavement systems 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-1958'><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: CBR, density, permeability, moisture content, Atterberg limits, soil classification.
• Fiber properties: diameter, length, specific gravity, tensile strength, and modulus of elasticity
• Soil-fiber matrix: shear strength, internal friction angle, cohesion, ductility, stiffness, resilient modulus, and CBR
</td></tr><tr><td ><center>QC</td><td ><center>Process Control</td><td >• Sand cone density, DCP, FWD/LFWD
</td></tr><tr><td ><center>QA</td><td ><center>Material Related</td><td >• Sand cone density, DCP, FWD/LFWD
</td></tr><tr><td ><center>QA</td><td ><center>Process Control</td><td >• Sand cone density, DCP, FWD/LFWD
</td></tr></tbody></table><br><h3>TABLE 2. PERFORMANCE CRITERIA USE IN QC/QA MONITORING PROGRAMS</h3><table class='tablepress' id='tablepress-1959'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Parameters</td><td >• Density, CBR, resilient modulus
</td></tr><tr><td ><center>System Behavior</td><td >• Roughness, serviceability index, rut depth, and fatigue cracking
</td></tr></tbody></table><br><h3>TABLE 3. EMERGING QC/QA PROCEDURES AND MEASUREMENT ITEMS</h3><table class='tablepress' id='tablepress-1960'><thead><th><center>Topics</th><th><center>Items</th></thead><tbody><tr><td ><center>Material Related</td><td >• Intelligent compaction</td></tr><tr><td ><center>Process Control</td><td >• None noted</td></tr></tbody></table></p></p>
<p><p><h2>QC/QA Guidelines</h2>Quality control and assurance of the fiber material is monitored by testing batches of fiber for consistency of length, diameter, and denier. During placement and compaction of in-situ or borrow material/fiber matrix, penetration tests are conducted before and after curing, mixing, and compaction to determine the increased strength of the material.</p><p>There are few fiber reinforcement case histories in which field density tests and plate load tests have been used for QC/QA. In the majority of the fiber reinforcement mix references, laboratory tests of the raw materials and the mix have been conducted. While controlled environment laboratory tests provide some level of QC/QA, there is a limited record of their use in any case histories of fiber reinforcement of pavements.</p><p>Material samples of the mixed, cured, and compacted matrix can also be taken and tested in a laboratory with CBR, triaxial, and direct shear tests.</p><p>During compaction, the on-board computer provides real-time data regarding the treatment. This data is then applied to quality control of the process and the equipment performance.</p><p>Currently, the QC/QA procedures for fiber reinforcement are somewhat inadequate. In-situ penetration testing, which provides a good indication of strength improvement, is constrained by the adequate testing coverage of the improved area unless many tests are conducted. An on-board computer is an excellent tool for quality assurance. Additional research into QC/QA is advised in order to allow for a better evaluation for the fiber reinforcement procedure. The potential of various other QC/QA tests should be investigated.</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><h2>References</h2>AASHTO (1993). <em>AASHTO Guide for Design of Pavement Structures</em>. American Association of State Highway and Transportation Officials, Washington, DC.</p><p>AASHTO (2008). <em>Mechanistic-Empirical Pavement Design Guide</em>, Interim Edition: A Manual of Practice, the AASHTO Mechanistic-Empirical Pavement Design Guide, Interim Edition. American Association of State Transportation and Highway Officials, Washington, DC.</p><p>Bhattacharya, P.G., and Pandey B.B. (1984). “Study of strength and curing of lime-stabilised laterite soil-plain and fiber-reinforced.” <em>Highway Research Bulletin</em>, pp. 1-22.</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…, N.C, Prietto, P.D.M., and Ulbrich, L.A. (1998b). “Influence of fiber and cement addition on behavior of sandy soil.” <em>Journal of Geotechnical and Geoenvironmental Engineering</em>, Vol. 124, No. 12, pp. 1211-1214.</p><p>Consoli, N.C., Casagrande, M.D.T., Prietto, P.D.M., and Thome, A. (2003a). “Plate load test on fiber-reinforced soil.” <em>Journal of Geotechnical and Geoenvironmental Engineering</em>, Vol. 129, No. 10, pp. 951–955.</p><p>Consoli, N.C, Vendruscolo, M.A., and Prietto, P.D.M. (2003b). “Behavior of plate load tests on soil layers improved with cement and fiber.” <em>Journal of Geotechnical and Geoenvironmental Engineering</em>, Vol. 129, No. 1, pp. 96-101.</p><p>Crockford, W.W., Grogan, W.P., and Chill, D.S. (1993). “Strength and life of stabilized pavement layers containing fibrillated polypropylene.” <em>Transportation Research Record</em> Vol. 1418, pp. 60-66.</p><p>Grogan, W.P. and Johnson, W.G. (1993). “Stabilization of high plasticity clay and silty sand by inclusion of discrete fibrillated polypropylene fibers for use in pavement subgrades.” Tech. Rep. CPAR-GL-93-3, the US Army Corps of Engineers.</p><p>Kalantari, B. and Huat, B.B.K. (2008). “Peat soil stabilization, using ordinary Portland cement, polypropylene fibers, and air curing technique.” <em>The Electronic Journal of Geotechnical Engineering</em>, Vol. 13, Bund. J.</p><p>Khattak, M.J. and Alrashidi, M. (2006). “Durability and mechanistic characteristics of fiber reinforced soil–cement mixtures.” <em>The International Journal of Pavement Engineering</em>, Vol. 7, No. 1, pp. 53-62.</p><p>Kaniraj, S.R. and Havanagi, V.G. (2001). “Behavior of cement-stabilized fiber-reinforced fly ash-soil mixtures.” <em>Journal of Geotechnical and Geoenvironmental Engineering</em>, Vol. 127, No. 7, pp. 574-584.</p><p>Kumar, A., Walia, B.S., and Mohan, J. (2006) "Compressive strength of fiber reinforced highly compressible clay." <em>Construction and Building Materials</em>, pp. 1063-1068.</p><p>Kumar, A., Walia, B.S., and Bajaj, A. (2007). “Influence of fly ash, lime, and polyester fibers on compaction and strength properties of expansive soil.” <em>Journal of Materials in Civil Engineering</em>, Vol. 19, No. 3, pp. 242-248.</p><p>Kumar, P. and Singh, S.P. (2008). "Fiber-Reinforced Fly Ash Subbases in Rural Roads," <em>Journal of Transportation Engineering</em>, Vol. 134, No. 4, pp. 171-180.</p><p>Liang, R. (1992). “Experimental and theoretical study of flexural behavior of polymer fiber reinforced, cement-treated soils.” Geotechnical Special Publication No. 30: <em>Grouting, Soil Improvement and Geosynthetics</em>, pp. 1080-1091.</p><p>Medjo Eko, R. and Riskowski, G. (1994) "Effects of fibers and cement on the mechanical behavior of soil-cement reinforced with sugar cane bagasse," <em>International Journal for Housing Science and Its Applications</em>, Vol. 18, No. 2, pp. 79-89.</p><p>Newman, J.K. and White, D.J. (2008). “Rapid assessment of cement and fiber-stabilized soil using roller-integrated compaction monitoring.”<em> Journal of the Transportation Research Board,</em> No. 2059, Transportation Research Board of the National Academies, Washington, D.C., pp. 95–102.</p><p>Puppala, A.J. and Musenda, C. (2000). “Effects of fiber reinforcement on strength and volume change in expansive soils.” <em>Transportation Research Record, </em>No. 1736, pp. 134-140.</p><p>Rafalko, S.D., Brandon, T.L., Filz, G.M., and Mitchell, J.K. (2007). “Fiber reinforcement for rapid stabilization of soft clay soils.” <em>Transportation Research Record</em>, No. 2026, Transportation Research Board of the National Academies, Washington, D.C., pp. 21-29.</p><p>Sivakumar Babu, G.L. and Vasudevan, A.K. (2008). “Strength and stiffness response of coir fiber-reinforced tropical soil.” <em>Journal of Materials in Civil Engineering</em>, Vol. 20, No. 9, pp. 571–577.</p><p>Tang, C., Shi, B., Gao W., Chen, F., and Cai, Y. (2007). “Strength and mechanical behavior of short polypropylene fiber reinforced and cement stabilized clayey soil.” <em>Geotextiles and Geomembranes,</em> Vol. 25, No. 3, pp. 194–202.</p><p>Tingle, J.S., Santoni, R.L., and Webster, S.L. (2002). “Full-scale field tests of discrete fiber reinforced sand.” <em>Journal of Transportation Engineering</em>, Vol. 128, No. 1, pp. 19-16.</p></p>