Methods, systems, and computer program products for measuring the density of material. According to one aspect, a nuclear density gauge is disclosed for measuring the density of a sample construction material. The gauge includes a radiation source positioned in an interior of a sample construction material and adapted to emit radiation from the interior of the sample construction material. Further, a radiation detector is positioned apart from the radiation source. The radiation detector is operable to produce a signal representing an energy level of detected radiation. A material property calculation function is configured to calculate a value associated with the density of the sample construction material based upon the signal produced by the radiation detector. Further, the radiation source may be positioned on a surface of the sample construction material and adapted to emit radiation towards the surface of the sample construction material.