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247 1.63.8 Structural Design No structural design guidelines were given. 1.63.9 Limitations No specific limitations were given. 1.64 Frick, K. âEvaluation of New Patching Material for Open-Graded Asphalt Concrete (OGAC) Wearing Courses.â Technical Memorandum TM-UCB- PRC-2â5-9. California Department of Transportation. June 2005. 1.64.1 General This Technical Memorandum provides an overview of an internal research project conducted by the California Department of Transportation to evaluate a commercial product for patching OGFC layers. The patching product was a combination of rapid- setting urethane polymer and a blend of hydrophobic polymer-coated open-graded aggregates. The product is mixed on the paving project using a 5-gallon bucket mixes. [Pictures within the document show a concrete mixer being used to mix the material.] Materials used in the mixing process are blended at ambient temperature. The urethane polymer is not a viscoelastic material like asphalt binder and takes about two hours to cure. Frick indicated that the process is easy and requires minimal equipment and training. Aggregates used in the patching material were open-graded to allow water to pass through the patch. In order to create the open-grading, a large percentage of pea gravel was placed in the aggregate blend. Frick states that the inclusion of the rounded pea gravel was not a concern because the polymer used in the mix is not dependent on temperature. 1.64.2 Benefits of Permeable Asphalt Mixtures Frick identifies the OGFCâs ability to drain water from the pavement surface as a benefit of OGFC. Because of the ability to drain water from the pavement surface, safety to the traveling public is improved as the potential for hydroplaning and splash/spray is reduced. 1.64.3 Materials and Mix Design No specifics on materials and mix design of PFC were provided. 1.64.4 Construction Practices As stated previously, the patching material is mixed on-site. For the projects described in the Technical Memorandum, no specifics were provided on how the material was placed onto the roadway. However, based upon a photograph within the document, the material was simply spread by hand over the patched area. 1.64.5 Maintenance Practices No specifics were provided on maintenance practices.
