Moisture damage in asphalt mixtures using the modified SATS test and image analysis

This study investigated damage in asphalt due to moisture by using the modified saturation ageing tensile stiffness (SATS) test along with image analysis. Specimens made from both granite and limestone aggregate with a 40/60 penetration grade bitumen were tested in the modified SATS test. The samples were scanned within an X-ray CT facility before the SATS testing, after the initial saturation and at the completion of the SATS test. Bitumen was extracted from tested specimens and scanned separately in a high resolution Nanotom (high resolution X-ray CT). The extracted bitumen was tested in a DSR for shear rheological properties. The specimens made from granite (acidic) and limestone (basic) aggregate were found to have similar permeability and this was found to be high for specimens having high design air void content. Specimens made from basic aggregate had higher stiffness than the specimens made from acidic aggregate. The master curves of the aged binder are different from those of the virgin binder (bitumen). Also the microstructure of binder observed was different for aged and virgin binder.