A COMPARISON OF FIELD AND BLOCKS CALIBRATION OF NUCLEAR DENSITY/MOISTURE GAUGES

Nuclear density/moisture gauges do not directly measure density and moisture content, but must be calibrated against results obtained using other means of measuring these properties. This paper compares density calibrations obtained in the field using sand replacement-type tests in accordance with Australian Standard AS1289.E.8.3 with those obtained in the laboratory using standard blocks in accordance with Australian Standard AS1289.E.8.4. Marked differences can occur between density estimates derived from field and blocks calibrations, and the difference can be positive or negative and up to about the same magnitude in each direction. No inference can be drawn as to the relative accuracy of the two calibration procedures. However, the blocks method presents several major practical benefits compared with the field method. (Author/TRRL)