Relationship between the Representative Volume Element and Mechanical Properties of Asphalt Concrete

Abstract

The size of an asphalt concrete test specimen has been traditionally determined based on experience and practical purposes. This study discusses theoretical considerations for selecting the minimum dimensions so that the resulting size of the specimen represents global material properties. The ideal size of the specimen was determined using an image analysis approach and was verified with mechanical tests. The image analysis was accomplished by studying the internal structure of asphalt concrete. The internal structure was captured using a nondestructive X-ray computer tomography technique. Mechanical testing was accomplished by using the Superpave Shear Tester on laboratory-prepared samples. The laboratory samples had dimensions that were both smaller and larger than the theoretically determined representative size. Statistical analysis indicates that the variability of the results is a function of the loading mechanism used in the Superpave Shear Tester. In general, the required representative size increased considerably when the nominal aggregate size was larger than 25.0 mm.