Performance Evaluation of In-situ and Laboratory Prepared Asphalt Materials: Practical Considerations for Sample Preparation and Testing Methodology

Abstract
Research and implementation of Performance Engineered Pavements (PEP) have been gaining momentum, especially during the past two decades. Several factors including but not limited to the sample preparation methods, specimen dimensions, compaction level, performance testing method, variability of results, minimum and maximum thresholds, and sensitivity to materials sources can be named among other major contributors in this area. This paper provides a summary of major procedures and protocols used by national and international transportation agencies toward performance testing. Furthermore, this paper presents a synthesis of the critical steps that should be considered by highway agencies in utilizing performance testing into design, performance verification, and/or quality assurance part of contracts. Successful implementation of this approach requires understanding the rationale behind development of the commonly used methods. Therefore, this paper also provides relevant aspects of the research work behind development of most specified test methods, and how several factors could influence the accuracy and variability of the test results. To this end, factors such as: air voids, thickness variation, cutting and coring methods, and compaction using gyratory or slab compactors, are considered and discussed in this paper.