Research + Results
To compare the current methods against the new non-destructive methods, a validation study was conducted. The geotech and asphalt groups evaluated two types of density gauges along with typical coring (for asphalt) and density measurements. For asphalt, the density gauges were nuclear and non-nuclear (electric pulses); for geotech, the density gauges were nuclear and low nuclear (smaller gamma source).
Researchers in the asphalt group determined that the non-destructive alternatives to measuring density, such as the non-nuclear gauges, are accurate and economically feasible. Mata explained, “Based on the results of the asphalt research, we recommend the use of the non-destructive testing for both QC and QA testing, provided the manufacturer’s and AASHTO T-343’s recommendation is followed to calibrate the device daily by applying a core-calibration offset.”
However, while still hopeful of future technological improvements, the geotech group decided to continue with the conventional methods due to a concern with the low nuclear density gauge’s probe depth and short life cycle.