Rubber Modified Asphalt Binders

Performance

Although a State may have a number of years of experience with a particular CRM technology, the performance of that technology can only be measured by the product/application combination for which it is used. The three basic types of asphalt paving products are sealants, thin surface treatments, and hotmix asphalt. Each of these product types can be further subdivided by the combination and proportion of materials used. A paving application is identified by the pavement distress pattern(s) that are being addressed by the project design.

Performance measurements are based on the degree of distress observed in the pavement and may include one or more different performance parameters. Typical parameters are ride, rutting, cracking, skid, splash/pray, fatigue, and aging. The four general categories of variables that will affect pavement performance are: (1) pavement design/rehabilitation strategy, (2) materials, (3) mix design, and (4) construction. The strategy chosen for a specific project must coincide with the desired performance parameters and the expected climate/traffic conditions. Proper selection of compatible, quality materials is essential. The appropriate mix design procedure must be performed correctly to determine the optimum proportion of materials and related engineering property limits. Finally, the best preconstruction design effort will not guarantee an acceptable performing pavement unless the pavement is properly constructed. Every step of the project must be accomplished with the correct engineering decisions for the pavement to achieve its intended performance. Pavements that do not perform as expected can usually be traced back to an incorrect decision in the process. When new materials are introduced into the mixture, each step of the process may require modification to achieve optimum performance. The performance of pavements built with CRM technology have had both successes and failures. The successes represent correct project selection, design engineering, and construction decisions. The failures generally reflect inexperience with CRM technology in project selection, design engineering, and construction decisions. Reported successes in one region of the country do not immediately substantiate success in other regions since all the variables do not remain the same.