In recent years, the subject of open-graded drainage layers, often referred to as "drainage blankets", has been utilized increasingly for pavement drainage. This study addresses the use of drainage blankets in Kentucky. Study efforts have focused on construction, performance, materials, and design considerations of drainage blankets.

Study findings are that the Number 57 gradation provides the optimum drainage and structural stability of the standard gradations evaluated. Asphalt treated aggregate provides greater stability and a better working platform than untreated aggregate. Maintenance of collector system outlets is very poor. Daylighting of drainage blankets appears to be feasible. Drainage blankets can be given structural value in pavement design but the structural coefficient, especially for untreated material, has not been satisfactorily established at this time. There is no clear evidence that drainage blankets extend pavement life as constructed and maintained.

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The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the University of Kentucky, the Kentucky Transportation Cabinet, nor the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. The inclusion of manufacturer names and trade names are for identification purposes and are not to be considered as endorsements.