scope:

This Standard Test Method sets out the method for determining the field water content and field dry density of a compacted aggregate using a nuclear surface moisture-density gauge in the direct transmission mode of operation. The method is appropriate to aggregates having a nominal maximum particle size of 40 mm (see Note (1)).

This type of gauge determines the gross mass per unit volume (wet density) of the aggregate and the mass of water per unit volume of the aggregate. Field dry density and water content can be calculated from these values. Aggregates containing chemically bound water or hydrocarbons, some aggregates of volcanic origin and aggregates that have been modified by cement, lime or bitumen will require the water content calibration of the gauge to be determined on the material under test. Wet densities can usually be measured satisfactorily on these materials.

NOTE - Because of the variety of gauges available, this method does not detail the operation of the gauge but refers the operator to the manufacturer's handbook.

When nuclear gauges are used for density measurement, the quantity of material being assessed is not precisely known. However, reference to the manufacturer's handbook and current literature indicates the likely volume. Nuclear gauges give an indirect measure of field density and water content and hence require calibration.