Research on Application of Pavement Quality Indicator for Asphalt Pavement Construction Quality Control in China

Controlling the density of hot mix asphalt (HMA) during the construction of asphalt pavements is an important factor that can directly affect the quality and the long-term performance of the pavements. The Pavement Quality Indicator (PQI), a non-radiation, electromagnetic based device provides an attractive alternative for monitoring asphalt pavement density in the field during the construction. This is particularly appealing to the asphalt paving industry in China as the potential exposure to radiation hazards for using the nuclear density gages has deterred the pavement construction industry from using them. That leaves the coring process to be the only alternative, which is time-consuming, costly, and destructive to new pavements. The use of PQI for monitory asphalt pavement density during the construction is very limited in China. There are several reasons that have contributed to that. One of them is the lack of reliable field data of using PQI for measuring HMA density in China. This paper presents several research studies for collecting HMA density data measured using PQI and that from the coring process in several asphalt pavement construction project in China. Analyses of these data as summarized in this paper have confirmed the viability of using PQI for measuring HMA density in the field as a means for asphalt pavement construction quality control. The differences between the density readings from the PQI and that from the core samples were very small. It also showed the importance of pre-calibration of the device using the same asphalt mat, otherwise significant error could occur. Three case studies of using PQI for monitoring asphalt mat compaction density are presented to demonstrate the potential benefits of using PQI for quality assurance (QA) of asphalt pavement construction.