<p><p><strong>References:<br></strong><em>Al-Qadi et al. (2004)<br>Christopher et al. (2010)<br>Elseifi et al. (2001)<br>Maser (1996)</em></p><p><strong>Method Summary</strong></p><p>Ground penetrating radar (GPR) is used to estimate the moisture content of granular base layers in pavement sections, preferably one with and one without an open-graded base drainage layer with geotextile filter or a geocomposite drainage system. The effect of moisture on pavement structural integrity is evaluated by a deflection monitoring program using a falling weight deflectometer (FWD). Temperature and moisture sensors may be placed on both sides of the geocomposite, while three pressure cells may be installed under the geocomposite. The geosynthetic can also be strain gaged to measure load response.</p><p><strong>Accuracy and Precision</strong></p><p>The method accurately and precisely measures the distribution of moisture in the pavement and the thickness of the pavement. The pavement thickness estimated by GPR is accurate and within 3-15% error as compared with that obtained through conventional core samples.</p><p><strong>Adequacy of Coverage</strong></p><p>Pavement thickness and moisture distribution can be accurately determined with a reasonable number of tests.</p><p><strong>Implementation Requirements </strong></p><p>The method surveys the pavement quickly at a low cost with minimal traffic disruption and safety risk. However, the equipment may not be available to owners or contractors. Hence the implementation is straight forward and easy to be incorporated into a QC/QA procedure if the equipment is available.</p><p><strong>General Comments</strong></p><p>The QC/QA method is applicable to performance-related specification. If the equipment is available, it can be adopted as the QC/QA method to evaluate the effectiveness of geosynthetics in pavement drainage.</p></p>