ASTM D4452/D4452M-22 PDF

SIGNIFICANCE AND USE 5.1 Many geotechnical tests require the utilization of intact, representative samples of soil. The quality of these samples depends on many factors. Many of the samples obtained by intact sampling methods have inherent anomalies. Sampling procedures cause disturbances of varying types and intensities. These anomalies and disturbances, however, are not always readily detectable by visual inspection of the intact samples before or after testing. Often test results would be enhanced if the presence and the extent of these anomalies and disturbances are known before testing or before destruction of the sample by testing. Such determinations assist the user in detecting flaws in sampling methods, the presence of natural or induced shear planes, and the presence of natural intrusions, such as gravels or shells at critical regions in the samples, the presence of sand and silt seams, and the intensity of disturbances caused by sampling. 5.2 X-ray radiography provides the user with a picture of the internal massive structure of the soil sample, regardless of whether the soil is X-rayed within or without the sampling tube. X-ray radiography assists the user in identifying the following: 5.2.1 Appropriateness of sampling methods used. 5.2.2 Effects of sampling in terms of the disturbances caused by the turning of the edges of various thin layers in varved soils, large disturbances caused in soft soils, shear planes induced by sampling, or extrusion, or both, effects of overdriving of samplers, the presence of cuttings in sampling tubes, or the effects of using bent, corroded, or nonstandard tubes for sampling. 5.2.3 Naturally occurring fissures, shear planes, etc. 5.2.4 The presence of intrusions within the sample, such as calcareous nodules, gravel, or shells. 5.2.5 Sand and silt seams, organic matter, large voids, and channels developed by natural or artificial leaching of soil components. Note 1: The quality of the results produced by this standard is de... SCOPE 1.1 This practice covers the determination of the quality of soil samples in thin wall tubes or of extruded soil cores by X-ray radiography. 1.2 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. 1.3 This practice can be used to X-ray soil 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 [1/4 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. 1.4 Greater detail and resolution of various features of the soil can be obtained by X-raying extruded soil cores, as compared to samples in metal tubes. The method used for X-raying soil 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 troughs (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. 1.4.1 Often it is necessary to obtain greater resolution of features to determine the propriety of sampling methods, the representative nature of soil samples,...