[en] This research ascertains if the Troxler Model 3241 Gauge could accurately determine the asphalt content of bituminous-concrete mixtures by nuclear means. The study was divided into three phases. Phase I was conducted in the Central Laboratory where a series of controlled tests were performed for variables that may effect the gauge's asphalt-content determinations. Phase II evolved into a cooperative study between the Maryland State Highway Administration (SHA) and several bituminous concrete producers. Phase III was to report the findings of the study and make a recommendation on the overall practical application of the gauge. The results indicate that the gauge can accurately determine asphalt contents on normal surface and base bituminous mixtures