- 期刊
Evaluation of the Dielectric Constants and Air Voids of Asphalt Concrete Using a Parallel Plate Method
並列摘要
The density of a hot-mix asphalt (HMA) pavement is one of the most important factors influencing the pavement quality. In Korea, pavement density is generally determined by measuring the bulk density of core samples. The more convenient way measuring pavement density in the field is to use the non-destructive pavement density testing devices. Recently, the dielectric properties of pavements have been used in these devices. The dielectric-type pavement density testing devices have an inherent advantage over core measurements and nuclear density gauges in that coring and extra security precautions are not required. The literatures show that dielectric constants are varied with the density and air void of materials. However, the dielectric constants of asphalt materials have not been tested and evaluated until recent in Korea. In this study, the dielectric constants and air voids of asphalt concrete were evaluated. Two types of asphalt concrete specimens were prepared with one type of aggregate and two types of asphalt binder; PG 64-16 and PG 82-22. Asphalt mixtures were compacted using a gyratory compactor at 0 to 20% of air voids, and then cut to the size of 150mm in diameter and 25mm in thickness. Parallel plate methods using low frequency (100KHz to 50MHz) impedance analyzer were used to measure the dielectric constants of asphalt concrete specimens. Test results showed that dielectric constants of asphalt concrete specimens were linearly decreased as frequency increased. The change rate of dielectric constants of PG 82-22 specimen was higher that of PG 64-16. The dielectric constants were rapidly increased at 20MHz of frequency due to the resonance nature of test, Test results also showed that dielectric constants of asphalt concrete specimens were linearly decreased as air void increased. The correlation models between dielectric constants and air voids of asphalt concrete were suggested by linear regression.