【国外标准】 Standard Test Method for Soundness of Aggregates by Use of Sodium Sulfate or Magnesium Sulfate

4.1 This test method provides a procedure for making a preliminary estimate of the soundness of aggregates for use in concrete and other purposes. The values obtained may be compared with specifications, for example Specification C33/C33M, that are designed to indicate the suitability of aggregate proposed for use. Since the precision of this test method is poor (Section 13), it may not be suitable for outright rejection of aggregates without confirmation from other tests more closely related to the specific service intended.4.2 Values for the permitted-loss percentage by this test method are usually different for fine and coarse aggregates, and attention is called to the fact that test results by use of the two salts differ considerably and care must be exercised in fixing proper limits in any specifications that include requirements for these tests. The test is usually more severe when magnesium sulfate is used; accordingly, limits for percent loss allowed when magnesium sulfate is used are normally higher than limits when sodium sulfate is used.NOTE 2: Refer to the appropriate sections in Specification C33/C33M establishing conditions for acceptance of coarse and fine aggregates which fail to meet requirements based on this test.1.1 This test method covers the testing of aggregates to estimate their soundness when subjected to weathering action in concrete or other applications. This is accomplished by repeated immersion in saturated solutions of sodium or magnesium sulfate followed by oven drying to partially or completely dehydrate the salt precipitated in permeable pore spaces. The internal expansive force, derived from the rehydration of the salt upon re-immersion, simulates the expansion of water on freezing. This test method furnishes information helpful in judging the soundness of aggregates when adequate information is not available from service records of the material exposed to actual weathering conditions.1.2 The values stated in SI or inch pound units shall be regarded separately as standard. The inch –pound units are shown in brackets. The values stated are not exact equivalents; therefore each system shall be used independently of the other. Combining values from the two systems may result in nonconformance.1.3 Some values have only SI units because the inch-pound equivalents are not used in practice.1.4 If the results obtained from another standard are not reported in the same system of units as used by this test method, it is permitted to convert those results using the conversion factors found in the SI Quick Reference Guide.2NOTE 1: Sieve size is identified by its standard designation in Specification E11. The alternate designation given in parentheses is for information only and does not represent a different standard sieve size.1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.