IS 2720 Pt.38-1976

标准号：IS 2720 Pt.38-1976
发布日期：1976/8/1 12:00:00
实施日期：1999/12/31 12:00:00
适用范围：1.1 This standard (Part XXXVIII) describes the procedure for determining the relative compaction and/or the difference between the optimum moisture content and the field water content of a soil by relating 'converted' wet density and 'added' water, without the immediate need to determine the water content. It is a rapid method based on tests covered by IS : 2720 (Part VII)-1974f and IS: 2720 (Part VIII)-1974〓 using a 1 000 cm3 mould. Usually, the results of only three compacted test specimens are required and both the test and the calculations can be done in less than an hour.1.1.1 The control parameters are determined either for the total material or for the material finer than a specified IS Sieve (see Note).Note — In construction control of coarse earth-fill it is often necessary to determine the field dry density of a certain fraction of the soil after excluding the mass and volume of all particles coarser than a specified sieve (usually 20-mm or 40-mm IS Sieve) in accordance with tests covered in IS: 2720 (Part XXVIII) -1974§ and IS : 2720(Part XXIX)-1975*. The rapid compaction test is performed on that fraction of the soil which is finer than the specified sieve. The size of the sieve should ensure that not less than 85 percent, by mass, of the total material is tested.1.1.2 Because it is a rapid method the refinement of proper curing is necessarily omitted. There is also some relaxation in the maximum particle size to allow compaction of material up to 25 mm size. These relaxations may result in minor differences between results obtained from tests covered in IS: 2720 (Part XXVIII)-1974〓 and IS: 2720 (Part XXIX)-1975*, especially in more cohesive soils and soils with a rock fraction.1.1.3 The test may be used for checking material before placement to ensure that the water content is within specified limits (see Note).Note — Samples which have been taken for testing before placement of the material may require pretreatment to simulate the effects of excavation and construction operations on particle breakdown and other physical properties. When previous tests have shown that significant changes in soil properties will occur during construction, pretreat the sample for the appropriate time by the method adopted in the laboratory to simulate the effects of the construction operations. One suitable method of pretreatment may be by mixing in a mechanical mixer.