ASTM International

Standard Practice for X-Ray Radiography of Soil Samples
 N D4452

Annotation

This practice covers the determination of the quality of soil samples in thin wall tubes or of extruded cores by X-ray radiography.

This practice enables the user to determine the effects of sampling and natural variations within samples as identified by the extent of the relative penetration of X-rays through soil samples.

This practice can be used to X-ray cores (or observe their features on a fluoroscope) in thin wall tubes or liners ranging from approximately 50 to 150 mm (2 to 6 in.) in diameter. X-rays of samples in the larger diameter tubes provide a radiograph of major features of soils and disturbances, such as large scale bending of edges of varved clays, shear planes, the presence of large concretions, silt and sand seams thicker than 6 mm ( in.), large lumps of organic matter, and voids or other types of intrusions. X-rays of the smaller diameter cores provide higher resolution of soil features and disturbances, such as small concretions (3 mm (1 8 in.) diameter or larger), solution channels, slight bending of edges of varved clays, thin silt or sand seams, narrow solution channels, plant root structures, and organic matter. The X-raying of samples in thin wall tubes or liners requires minimal preparation.

Greater detail and resolution of various features of the soil can be obtained by X-raying of extruded cores, as compared to samples in metal tubes. The method used for X-raying cores is the same as that for tubes and liners, except that extruded cores have to be handled with extreme care and have to be placed in sample holders (similar to Fig. 2) before X-raying. This practice should be used only when natural water content or other intact soil characteristics are irrelevant to the end use of the sample.

Often it is necessary to obtain greater resolution of features to determine the propriety of sampling methods, the representative nature of soil samples, or anomalies in soils. This practice requires that either duplicate samples be obtained or already tested specimens be X-rayed.