Significance and Use
The shrinkage factors covered in this test method can only be determined on basically fine-grained (cohesive) soils which exhibit a dry strength when air dried.
The term shrinkage limit, expressed as a water content in percent, is typically assumed to represent the amount of water required to fill the voids of a given cohesive soil at its minimum void ratio obtained by drying (usually oven). Thus, the concept shrinkage limit can be used to evaluate the shrinkage potential or possibility of development, or both, of cracks in earthworks involving cohesive soils.
Data obtained from this test method may be used to compute the volumetric shrinkage and linear shrinkage.
Note 1—Notwithstanding the statements on precision and bias contained in this test method, the precision of this test method is dependent on the competence of the personnel performing it and the suitability of the equipment and facilities used. Agencies which meet the criteria of Practice D 3740
1.1 This test method covers a procedure for obtaining the data which are used to calculate the shrinkage limit and the shrinkage ratio.
1.2 This test method uses mercury which is a hazardous substance. Test Method D 4943 does not use mercury and is an acceptable alternate to this procedure.
1.3 The liquid limit, plastic limit, and shrinkage limit are often collectively referred to as the Atterberg Limits in recognition of their formation by Swedish soil scientist, A. Atterberg. These water contents distinguish the boundaries of the several consistency states of cohesive soils.
1.4 This test method is performed only on that portion of a soil which passes the 425-m (No. 40) sieve. The relative contribution of this portion of the soil must be considered when using this test method to evaluate the properties of the soil as a whole.
1.5 The values stated in SI units are to be regarded as the standard. The values stated in inch-pound units are approximate and given for guidance only. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard.
1.6 All observed and calculated values shall conform to the guidelines for significant digits and rounding practices established in Practice D 6026.
1.6.1 The method used to specify how data are collected, calculated, or recorded in this standard is not directly related to the accuracy to which the data can be applied in design or other uses, or both. How one applies the results obtained using this standard is beyond its scope.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. This test method involves the use of the hazardous material mercury (Warning-mercury is a definite health hazard in use and disposal), see Section 7.