Laboratory evaluation of electromagnetic density gauges for hot-mix asphalt mixture density measurement

This paper presents a laboratory study aiming to evaluate the performance of electromagnetic (EM) density gauges as a non-destructive tool for hot mix asphalt (HMA) density measurement. In total, 36 HMA testing slabs with different compositions were prepared in laboratory. EM density gauge data were collected from these slabs using two common types of gauges, i.e., PQI 301 and PaveTracker 2701B, and compared with their bulk densities measured by the standard saturated surface dry (SSD) method. It was found that measurement direction, asphalt binder content, mixture air void content, and thickness of the testing slabs do not affect the accuracy of the EM density gauges. However, EM density gauge measurements are affected by the presence of moisture, gradation of asphalt mixture and gauge calibration method. It was also concluded that the accuracy of PaveTracker with mix calibration is comparable to that of the conventional standard method.