NUCLEAR METERS FOR MEASURING SOIL DENSITY AND MOISTURE IN THIN SURFACE LAYERS

摘要

The measurement of soil density and moisture at varying depths by means of nuclear instruments was described previously in Civil Aeronautics Administration Technical Development Report No. 127. The present report describes the development of new meters that measure density and moisture of the surface layer of soil. Using the same radioactive sources and same counter tubes as used in the depth probes, but with a different geometric design, these preliminary models prove to be promising under both laboratory and field conditions. Further studies are being made to improve their op¬erational characteristics, particularly that of sensitivity. When perfected, they can be used advantageously for compaction control and related purposes in all types of earth construction. They are efficient, conven¬ient, and economical. It takes about fifteen minutes to take measurements and obtain the results on a complete set of density and moisture readings.