<p><p><strong>References:<br></strong><em>Eaton and Berg (1980)<br>Smith and Pazsint (1975)</em></p><p><strong>Method Summary</strong></p><p>The pavement rebound is measured in a Benkelman beam test. The standard axle load for the Benkelman beam test on permanent roads is 18 kips. Measurement is made by placing the tip of a beam between the dual tires and measuring the pavement surface rebound as the truck is moved away.
<p><p><strong>Reference(s):<br></strong><em>Picornell-Darder (1985)</em></p><p>In this method, the depth of the moisture barrier is determined based on the information available for the climatic conditions and the soil properties for a specific site. The designer selects the meteorological design event and estimates the response of the soil profile to the design event. The design event is selected from a frequency analysis of the drought intensities that occur with a stochastic series of consecutive one-year meteorological events.
<p><p><strong>Reference(s):<br></strong><em>Steinberg (1998)</em></p><p>In this method, placement of a geomembrane vertically to a certain depth depends on the active zone of moisture activity. Basically, the width and depth of excavation vary from 0.065 to 0.1 meter and 1.5 to 3.0 meter, respectively. A double-layer geomembrane is laid into the trench as it is tougher and less likely to be damaged from construction and/or by tree root penetration. The geomembrane is placed using a specially designed dispenser.
<p><p><strong>Reference(s):<br></strong><em>Lord and Koerner (1986)</em></p><p>This design method is based on an analytical model for moisture flow in the composite system of soil, impregnated geotextile, and air. The method is directed towards the Membrane Encapsulated Soil Layer (MESL) problem, although the approach is applicable to a wide range of geomembrane situations.
<p><p><strong>References:<br></strong><em>Sale et al. (1973)<br>Smith and Pazsint (1975)<br>Smith (1979)<br>Steinberg (1998)</em></p><p><strong>Method Summary</strong></p><p>The optimum moisture content and the maximum dry density of the soil can be determined using the standard (ASTM D 698, AASHTO T 99) or modified Proctor tests (ASTM D 1557, AASHTO T 180). The moisture content and density during the construction are monitored.
<p><p><strong>References:<br></strong><em>Elseifi (2003)<br>Christopher et al. (2010)</em></p><p><strong>Method Summary</strong></p><p>This method assesses the moisture content in the encapsulated soil using Ground Penetration Radar (GPR) and Time Domain Reflectometer (TDR) probes. Falling Weight Deflectometer (FWD) or Light Weight Falling Weight Deflectometer (LFWD) tests can also be performed to evaluate resilient moduli of the subgrade before, during, and after construction.
<p><p><div></p><p><figure id='attachment_3545' style='max-width:697px' class='caption aligncenter'><img class="wp-image-3545 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph of partial encapsulation of subgrade soils with a moisture barrier along a roadway in Wyoming." width="697" height="410" /><figcaption class=�
<p><p><strong>References:<br></strong><em>Koerner (1994)<br>Picornell-Darder (1985)<br>Rankilor (1981)<br>Steinberg (1998)</em></p><p><strong>Method Summary </strong></p><p>Laboratory tests of a membrane are required to ensure that the membrane meets different engineering properties per the design specification.
<p><p><strong>References:<br></strong><em>Eaton and Berg (1980)<br>Picornell-Darder (1985)<br>Smith and Pazsint (1975)<br>Steinberg (1998)</em></p><p><strong>Method Summary</strong></p><p>The roughness in the pavement section is evaluated using a semi-annual survey with a profilometer. This survey provides the discrete elevation profile along the left and right sections of the surveying vehicle. The data from several overlapping sections are used to define the longitudinal profile.
Reference(s):
FHWA Geotechnical Aspects of Pavement (Christopher et. al. 2006, revised 2010)
<p><p><h2>Commentary</h2>Typical contract pay items and units of measurement used for partial encapsulation include:<br><ul> <li>Geomembrane measured by the square yard in-place</li></ul>The equipment used to construct partial encapsulation 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 partial encapsulation is similar to other geotextile applications.
<p><p><figure id='attachment_2618' style='max-width:670px' class='caption aligncenter'><img class="wp-image-2618 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Schematic cross section of partial encapsulation of subgrade soils along Interstate 37 in Texas." width="670" height="304" /><figcaption class='caption-text'> Cross Section
<p><p><h2>Summary of Example Specifications</h2></p><p><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> Geomembranes and Other Geosynthetic Barriers</div><strong>Reference(s):<br></strong><em>Holtz et al. (2008)-Chapter 10<br>AASHTO M288 (2006)</em></p><p>These are useful reference specifications for developing the guide specification. The specifications contain helpful commentary but are not complete as they are not based on the method approach for the construction. The specifications are easy to read, logically ordered, and provide clear instruction for completing the work. There are no conflicting statements in the specifications. However, the specifications are lacking information, such as design methodology, preconstruction meeting, etc. The risk is shared between the owner and the contractor. The contractor has to submit the details of the geomembrane such as manufacturer, product name, composition, and strength properties. The owner has to check the material and work done by the contractor as mentioned in the specification. The specifications do not include a section discussing the in-situ soil conditions or soil parameters. The contractor can bid on the work without needing additional information and the specification allows substitution for proprietary products. The specifications do not require overly elaborate or expensive construction methods. The specifications contain all the detailed requirements necessary for the QC/QA, as appropriate to the technology and specification type. The specifications contain most pertinent sections, as appropriate for the technology and specification type; however, they are not complete, such as lacking design methodology, preconstruction meeting and requirements for in-situ soil conditions or soil parameters.</p><p><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> Evaluation of Soil Moisture Barrier</div><strong>Reference(s):<br></strong><em>Mississippi Department of Transportation (MDOT) 1999</em></p><p>The specification is site-specific. The specification is easy to read, logically ordered, and provides clear instructions for completing the work. There are no conflicting statements in the specification. Risk is inappropriately allocated to the contractor. The duties and responsibilities of the contractor are defined in the specification. The contractor can bid on the work without needing additional information and the specification allows substitution for proprietary products. The specification does not require overly elaborate or expensive construction methods. The specification includes some detailed requirements for QC/QA, as appropriate to the technology and specification type, but it only provides general guidance for other aspects of QC/QA. The specification contains most of the necessary sections but is lacking some important items, such as a detailed construction procedure for using geomembrane in expansive soil, design method of geomembrane in construction, preconstruction meeting, minimum contractor qualifications, etc.</p><p><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> Polypropylene Geomembrane Product Specifications</div><strong>Reference(s):<br></strong><em>Colorado Lining International</em></p><p>The specification is prepared by the manufacturer as a method approach specification. It is easy to read, logically ordered, and provides clear instructions for completing the work. There are no conflicting statements in the specification. Risk is inappropriately allocated to the contractor. The contractor has to submit the details of the geomembrane, such as manufacturer, product name, composition, and strength properties. The contractor can bid on the work without needing additional information and the specification allows substitution for proprietary products. The specification does not require overly elaborate or expensive construction methods. The specification contains all the detailed requirements necessary for the QC/QA as appropriate to the technology and specification type. The specification contains most of the necessary sections but is lacking some important items, such as minimum contractor qualifications, preconstruction meeting, design methodology, soil parameters, etc.</p><p><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> Geomembrane and the Control of Expansive Soils in Construction</div><strong>Reference(s):<br></strong><em>Steinberg (1998)</em></p><p>The specification included in this book describes the method and performance approach specifications for the use of geomembrane in expansive soil. It is easy to read, logically ordered, and provides clear instructions for completing the work. There are no conflicting statements in the specification. Risk is shared between the owner and the contractor. The contractor has to submit the details of the geomembrane, such as manufacturer, product name, composition, strength properties. The owner has to check the material and work done by the contractor as mentioned in the specification. The contractor can bid on the work without needing additional information and the specification allows substitution for proprietary products. The specification does not require overly elaborate or expensive construction methods. The specification contains all the detailed requirements necessary for the QC/QA, as appropriate to the technology and specification type. The specification contains all pertinent sections, as appropriate for the technology and specification type. However, the specification is lacking much information, such as minimum contractor qualifications, preconstruction meeting, etc.</p><p></p></p>
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