Relationship between the representative volume element and mechanical properties of asphalt concrete

The size of an asphalt concrete test specimen has been traditionally determ ined based on experience and practical purposes. This study discusses theor etical considerations for selecting the minimum dimensions so that the resu lting size of the specimen represents global material properties. The ideal size of the specimen was determined using an image analysis approach and w as verified with mechanical tests. The image analysis was accomplished by s tudying the internal structure of asphalt concrete. The internal structure was captured using a nondestructive X-ray computer tomography technique. Me chanical testing was accomplished by using the Superpave Shear Tester on la boratory-prepared samples. The laboratory samples had dimensions that were both smaller and larger than the theoretically determined representative si ze. Statistical analysis indicates that the variability of the results is a function of the loading mechanism used in the Superpave Shear Tester. In g eneral, the required representative size increased considerably when the no minal aggregate size was larger than 25.0 mm.