Evaluation of a non-nuclear density gauge as an alternate to destructive coring for airport asphalt acceptance testing

Abstract

A non-nuclear density gauge (NNDG) was evaluated as part of an asphalt runway resurfacing project. The repeatability of the NNDG was found to be high but asphalt temperature and surface moisture had a significant effect on the reliability of NNDG inferred asphalt density. It was also found that a single NNDG inferred density, located immediately over the core location, provided greater agreement with core density than an averaged NNDG density over and around the location of the core. It was concluded that when used 1 day behind the surface paving operation, when the temperature had stabilised and the surface was dry, the NNDG was a reliable replacement for destructive coring for density measurement. Consequently, the coring frequency was reduced by 75% following NNDG calibration. However, the influence of temperature and moisture rendered the NNDG less suited to quality control during the compaction rolling process. Finally, it is recommended that additional research be undertaken to extend these conclusions to other asphalt mixtures, allowing other airports to reduce the frequency of destructive coring for density testing during asphalt resurfacing, following mixture-specific calibration of the NNDG.