This report presents a user's guide for an expert decision-making system that utilizes findings of an extensive literature search and review conducted as part of this study. The literature search and review were conducted to determine current attitudes and document available technical data relative to the use of recyclable and recoverable materials in highway construction and maintenance activities. Specifically, the literature search focused upon the engineering, economic, and performance aspects of using recyclable and recoverable materials in highway construction and maintenance projects. The effort centered upon asphalt and Portland cement concrete pavement recycling, discarded tire recycling, reuse of paint removal wastes, fly ash, glass, alternative fuels, and other miscellaneous recycled and recovered materials as related to construction and maintenance of highways. Additionally, regulatory and policy matters associated with the use of recyclable and recoverable materials in the transportation area were investigated during the review of pertinent literature.

The user's guide was developed for use by Kentucky Transportation Cabinet officials to address a large number of multi-disciplinary issues. These issues may include, but not be limited to, environmental impact legal or legislative mandates, performance, cost and implementation. Since the aforementioned variables change with time, there is a user-friendly updating feature for the expert decision-making system. This feature of the expert system format presentation represents a major advantage over the familiar report format. An expert system has three major parts: a user interface, an inference engine, and stored expertise. When consulting the expert system, the user states a problem and interacts with the system. An expert system's inference engine is software that actually carries out the reasoning needed to solve a problem. This software draws upon the stored expertise in order to reach its conclusions.

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The contents of this report reflect the views of the authors who are responsible for the facts and the 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 or trade names are not to be considered as endorsements.