Geosynthetic Separation in Pavement Systems Cost Information
<p><p><h2>Commentary</h2>Typical contract pay items and units of measurement used for geosynthetic separation in pavement systems include<br><ul> <li>Geosynthetic fabric measured by the square yard in-place</li></ul>The equipment used to construct geosynthetic separation in pavement systems is common to highway construction projects; therefore additional mobilization costs are negligible.<br><h2>Cost Information Summary</h2>The total labor and equipment cost associated with installation of geosynthetic separation in pa
Geosynthetic Separation in Pavement Systems Fact Sheet
<p><p><figure id='attachment_2589' style='max-width:831px' class='caption aligncenter'><img class="wp-image-2589" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of aggregate being spread out over a geotextile separation layer in a pavement system." width="831" height="569" /><figcaption class='caption-text'> (Photo courtesy of M
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Geosynthetic Separation in Pavement Systems Specifications
Summary of Example Specifications
<p><p><h2>Summary of Example Specifications</h2><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> Specification for Geotextiles Used in Separation and Stabilization Applications</div><strong>Reference(s):<br></strong><em>AASHTO M288 (2006)<br>Holtz et. al. (2008)<br></em>This specification is easy to read, logically ordered, and provides clear instructions for the construction procedure. It gives clearly defined material properties and a list of approved geotextiles. This guide is not complete for all the aspects of pavement construction because contractor minimum qualifications, equipment needed, and QC/QA after construction are not covered in this document.</p><p>A certificate has to be provided by the contractor to the engineer stating the name of the manufacturer, product name, style number, chemical composition of the fibers, and other necessary information for geotextiles. The contractor has to submit the seam assembly description including seam type, stitch type, sewing thread, and stitch density. Manufacturer is responsible for quality of the geotextiles to meet the requirements of the specification. Hence, the risk is appropriately shared between the owner and the contractor.</p><p>Contractors can bid on the work without needing additional information as it includes the basis of maintenance, measurement and pavement and the specification allows substitution for proprietary products however the section for minimum contractor qualifications is lacking.</p><p>The construction method in this specification is well-defined and do not have overly elaborated or expensive construction requirements.</p><p>The specification contains all the detailed requirements necessary for QC/QA. For the material related quality control, it includes soil property requirements (CBR and permeability) and geosynthetic property requirements (chemical composition of the geosynthetic fiber, grab strength, puncture strength, apparent opening size etc). It also addresses the construction process such as placement and compaction of base course, placement of geosynthetics, and overlap or seam requirement etc. But, this specification does not contain the information of the some performance criteria such as resilient modulus, rut measurement, surface curvature index (SCI), and base damage index (BDI). It also does not provide the information regarding the emerging technologies like Intelligent compaction control, FWD and GPR testing for the QC/QA procedure.</p></p>
GPR System
<p><p><strong>References:<br></strong><em>Al-Qadi and Appea (2003)<br>Loulizi et al. (1999)</em></p><p><strong>Method Summary </strong></p><p>Ground-Penetrating Radar (GPR) surveys are performed on the test sections to monitor any changes in the pavement systems. An electromagnetic wave is transmitted through the pavement layers using the GPR. The depth of the hidden interface can be calculated by measuring the time of reflection of the wave and known dielectric constant of the medium above the interface.
Highway SR-507, Bucoda, Washington
<p><p><figure id='attachment_3449' style='max-width:1024px' class='caption aligncenter'><img class="wp-image-3449 size-large" style="border: 2px solid #696969;" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Schematic diagram showing binding, clogging and caking in an aggregate and geosynthetic system overlying a subgrade." width="1024" height="
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Mechanistic approach
<p><p><strong>Reference(s):<br></strong><em>Al-Qadi and Appea (2003)</em></p><p>The structural integrity of the pavement is evaluated through back-analysis of the FWD data. The FWD test applies an impulse load to simulate the traffic load ( e.g. an impulse load of 40 kN in 40 ms is similar to that of a standard (40 kN) half-axle traveling at a typical highway speed (loading pulse of 40 ms)).
Rut Measurement
<p><p><strong>References:<br></strong><em>Al-Qadi and Appea (2003)<br>Guram et al. (1994)<br>Loulizi et al. (1999)</em></p><p><strong>Method Summary</strong></p><p>Rutting indicates the deformation and wear of the materials in the pavement. The deformation in the pavement may be due to the reduction of the resilient modulus of the base layer. The reduction of the resilient modulus can be occurred due to the migration of the fines from the subgrade into the base material.
Secondary Road Field Study, Bedford County, Virginia
<p><p><figure id='attachment_3447' style='max-width:696px' class='caption aligncenter'><img class="wp-image-3447 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph showing rutting in an asphalt pavement with a geosynthetic separation layer." width="696" height="525" /><figcaption class='caption-text'> Al-Qadi and Appea (2
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