Alternatives to nuclear densometer

Summary: A comprehensive search of the state-of-the-art for measuring in-place density of bound and unbound materials showed that only one manufacturer appeared to have equipment that could be used in place of the Nuclear Densometers currently being used. The equipment tested consisted of the Pavement Quality Indicator 380 for Hot Mixed Asphalt and the Soil Density Gage 200 for unbound soils and base course materials. This equipment was purchased from TransTech Systems, Inc. A comprehensive test program was set up to evaluate how this equipment works on actual projects and actual materials located throughout New Mexico. The results from the Soil Density Gage 200 indicated that it is extremely unreliable and inconsistent. Additionally, it was found to be very difficult to use and to read the screen under natural daylight conditions. The Pavement Quality Indicator was more consistent, but also the screen was equally difficult to see under normal daylight conditions. However, neither of these technologies allowed the elimination of the current Nuclear Densometer in use by the department. It is still necessary to utilize the Nuclear Densometer on a daily basis along with both the Pavement Quality Indicator 380 and the Soil Density Gage 200 in order to determine a daily correction factor by which the remaining results from the days measurements could be determined. Due to the extreme lack of reliability of the Soil Density Gage and the inability to replace the Nuclear Densometer with either of these technologies, it was the unanimous conclusion of the Technical Panel that, at this time, this technology is not appropriate for use in any application that involves project or material acceptance or the determination of pay factors.

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