Mechanical Stabilization of Subgrades and Bases Specifications
Summary of Example Specifications
<p><p><h2>Summary of Example Specifications</h2><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> Rock Stabilization of Subgrades</div><strong>Reference(s):<br></strong><em>“Section 510-Aggregate Stabilization,” <em>Standard Specifications for Roads and Structures. <<a href="http://%20www.ncdot.org/%20doh/%20preconstruct/%20ps/%20specifications/dual/defau… www.ncdot.org/ doh/ preconstruct/ ps/ specifications/dual/default.html</a>> (June, 2011)</em></em></p><p>The document is intended to be a generic specification for rock stabilization of subgrades. The contractor is responsible for the final product and any problems encountered during construction. The contractor is able to obtain information from the specification such as material and equipment requirements; however, the contractor may require additional information for bidding. The specifications have sections including material properties, construction methods, equipment requirements, and allowable tolerances. The specifications lack detailed requirements for QC/QA procedures. A detailed design is also absent and should be added in the specification.</p></p>
Nuclear Gauge Method
<p><p><strong>References:<br></strong><em>Al-Qadi et al. (1996)<br>Brandon et al. (1996)<br>Christopher et al. (2010)</em></p><p><strong>Method Summary</strong></p><p>The nuclear gauge method is commonly used to determine compacted field density and moisture content of stabilized soil (ASTM D2922, D3017 and D6938, AASHTO T238 and T239).
Routes 575 and 616 Intersection, Virginia
<p><p><h2>Project Summary/Scope:</h2>Inadequate materials over weak soil in pavement systems frequently lead to the deterioration of flexible pavement systems. Using a geosynthetic placed over a subgrade is an inexpensive and effective method to stabilize the flexible pavement. A field test was conducted and monitored for the performance of geosynthetic in pavement stabilization.
Soil Mixing
<p><p><strong>Reference(s):<br></strong><em>Barksdale (1991)<br>Krebs and Walker (1971)<br>Rollings and Rollings (1996)</em></p><p>Soil mixing can alter particle properties to help achieve better stability or drainage. Aggregate gradation is an important factor when engineers design pavement base courses.
State Route 20, Washington
<p><p><figure id='attachment_3513' style='max-width:794px' class='caption aligncenter'><img class="wp-image-3513 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Photograph showing grading of the rock cap aggregate on a roadway." width="794" height="539" /><figcaption class='caption-text'> Grading of rock cap aggregate.
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Static Plate Load Tests
<p><p><strong>References:<br></strong><em>Christopher et al. (2010)<br>Vennapusa and White (2009)</em></p><p><strong>Method Summary</strong></p><p>Static plate load tests involve obtaining load versus deflection curves to determine modulus of subgrade reaction, soil elastic modulus, or soil bearing capacity. The test is conducted by increasing a static load on the soil and recording the corresponding plate deflections.
Strain Gages
<p><p><strong>References:<br></strong><em>Al-Qadi et al. (1996)<br>Brandon et al. (1996)<br>Tsai et al. (1996)</em></p><p><strong>Method Summary</strong></p><p>Strain gages are used for measuring vertical strains throughout the cross section.