Study on the nuclear method used in earthworks quality control of civil infrastructures

Compaction is essential in earthworks of civil infrastructures, such as dam embankments, building foundations, roads, and other transport infrastructures. The nuclear method is a non-destructive test that has been one of the most used field tests in the quality control of compaction for a long time due to its easy operation and accuracy. The technique uses nuclear equipment to measure soil and aggregates' moisture content and in-situ density. The fidelity of the method according to Portuguese technology is still unknown. The paper has two main objectives: (1) to describe the application of the non-destructive testing method to the quality control of compaction; (2) to present the repeatability and reproducibility of the method in its application to the case of soils based on proficiency tests. The paper presents the methodology followed in carrying out the proficiency tests and analysing the results related to the method's fidelity. The work points out the most critical aspects of the test and presents the repeatability and reproducibility related to in situ density and moisture content in the cases of direct transmission and backscatter measurements.