| To improve the service life of flexible pavements, a study conducted by the Strategic Highway Research Program (SHRP) proposed new specifications for the asphalt binders commonly known as "Performance Grade (PG) Specifications." The main advantage of PG specifications is that the tests are performed at the pavement service temperatures. In addition, the new specifications included new test setups that evaluated fundamental mechanical properties of asphalt cement rather than empirical indicators like penetration tests.; To meet PG-specifications and to improve the performance of HMAC (Hot Mix Asphalt Concrete), various modifiers have been developed and added to the neat asphalt cement. Although laboratory tests results have indicated that the use of modifiers improves the HMAC performance, the documented field performance has been mixed. (Abstract shortened by UMI.)... |
