Air Void Detection Using Ground-Penetrating Radar and Its Relationship to Moisture Damage

摘要

Moisture transport in asphalt mixtures is influenced by the distribution and connectivity of air voids in the mixture. Therefore, characterization of air void structure is important for predicting moisture damage potential. The purpose of this paper was to detect the air void content of asphalt pavement using ground penetration radar (GPR) and then evaluate the moisture damage potential of asphalt mixtures with different air void contents. In particular, an innovative device, a dynamic water pressure tester (DWPT), was used to evaluate the resistance of asphalt mixture to moisture damage. A rotary loaded wheel tester (RLWT) was used to measure rutting resistance of asphalt mixture before and after being tested by DWPT. A linear relationship between air voids and the amplitudes of wave valley in the GPR signal was found. It suggested that the GPR waveform could be used to detect the air void content of asphalt pavement layers consistent with laboratory measurements. The relationship between air voids and rut depths measured with RLWT showed that an increase in air void content led to an increase in rut depth. Test results in the laboratory indicated that dynamic water pressure resulted in the greater reduction of strength and increase of rut depth if the asphalt mixture has higher air void contents.