Abstract: A nuclear density gauge and test method is provided for measuring density material in a relatively thin zone beneath a surface of the material. The gauge comprises a gauge housing and a substantially planar base on said gauge housing adapted to be positioned on a surface of the material sample. A gamma radiation source having a characteristic primary energy and an activity of no more than 100 microcurie is mounted within the housing and cooperates with the base for emitting gamma radiation through the base and into an underlying material sample. An energy selective gamma radiation detector is mounted within the gauge housing and in laterally spaced apart relation from the gamma radiation source. The gamma radiation detector is operable for quantifying the energy level of the detected gamma radiation. Shielding is provided within the gauge housing between the source and the detector for preventing gamma radiation from passing directly from said source to the detector.

Abstract: A nuclear density gauge and test method is provided for measuring bulk density, especially of a cylindrically shaped sample such as asphalt paving material. The gauge comprises a base; a sample holder carried by the base and having a surface configured for receiving and holding a first generally planar end of the cylindrically shaped sample; a plate mounted in proximity to said sample holder; and at least three sources of gamma radiation located in said plate adjacent the sample holder. The sources are positioned in spaced-apart relation from one another for emitting gamma radiation from at least three spaced-apart locations into said one end of the sample. Each of the sources comprises an isotope having a characteristic primary energy. A detector is mounted to the base and is positioned adjacent the opposite end of the cylindrically shaped sample for receiving gamma radiation which has penetrated the sample.

Abstract: An apparatus and method for assaying an asphalt-containing composite material by irradiating the sample using a radiation source having a tunable preselected wavelength selected to closely approximate the absorbance wavelength of a particular material or materials found in the composite material to reduce the overall time and temperatures ordinarily needed to combust and assay such samples.

Abstract: A nuclear density gauge and test method is provided for measuring density material in a relatively thin zone beneath a surface of the material. The gauge comprises a gauge housing and a substantially planar base on said gauge housing adapted to be positioned on a surface of the material sample. A gamma radiation source having a characteristic primary energy and an activity of no more than 100 microcurie is mounted within the housing and cooperates with the base for emitting gamma radiation through the base and into an underlying material sample. An energy selective gamma radiation detector is mounted within the gauge housing and in laterally spaced apart relation from the gamma radiation source. The gamma radiation detector is operable for quantifying the energy level of the detected gamma radiation. Shielding is provided within the gauge housing between the source and the detector for preventing gamma radiation from passing directly from said source to the detector.