Investigation of the excess pore water pressure inside compacted asphalt mixture by dynamic triaxial tests

Moisture damage is one of the major problems in asphalt pavements. The pore water in asphalt mixture pavements is easily evolved into excess pore water pressure under the action of the traffic load. According to the reverse fluid-solid coupling theory, the excess pore pressure of water damages the asphalt film or mastic on the aggregate surface, which results in splitting at the contact points among aggregates. Further, this excess pore water pressure scours, emulsifies, and strips the asphalt film surrounding the aggregates. Therefore, many problems occur in asphalt pavements. In this study, the excess pore water pressure of the compacted asphalt mixture was investigated by dynamic triaxial tests (DTT). The results show that with the increase of loading time, the excess pore water pressure has three typical stages. At the same time, the deviator stress and loading frequency both influence the peak value of the excess pore water pressure. The higher the deviator stress is, the greater the peak value of the excess pore water pressure is. Similarly, the bigger the loading frequency is, the greater the peak value of the excess pore water pressure is. These conclusions show that overloaded vehicles and high traffic capacity are the external influential factors of moisture-induced damage to asphalt mixtures.