Determination of Cement Content in Soil-Cement Mixtures and Concrete.

摘要

Mixing of portland cement with soils is a standard method of improving the quality of the sub-base for many of the roads built throughout Louisiana. The objective of this investigation is to develop a rapid and reliable technique for the determination of the amount of cement mixed with the soil. If the mixture is not within specifications,the bearing strength of the soil is reduced significantly. There is a need for a measurement system that will produce reliable data as soon as possible after the cement is mixed with the soil. Systems suitable for field determination of cement content of soil-cement mixtures or concrete has been developed. Samples are analyzed by producing a radioactive isotope of calcium,Ca-49,by neutron bombardment of the non-radioactive calcium. This is followed by measurement of the amount of Ca-49by the technique of gamma spectroscopy. Gamma spectroscopy allows an unambiguous identification of the Ca-49content which can be directly related to cement content for acceptable mixtures in use in Louisiana. The system uses a relatively new,man-made radioisotopic source of neutrons,californium-252.