【国外标准】 Standard Test Method for Restrained Expansion of Expansive Cement Mortar

This test method covers the standard procedure for determination of length changes of expansive cement mortar, while under restraint, due to the development of internal forces resulting from hydration of the cement. The test apparatus is comprised of the following: molds for casting test specimens; restraining cage which consists of a threaded steel rod with steel end plates held in place by cap nuts for corrosion prevention; length comparator; tamper which shall be made of nonabsorptive, nonabrasive material such as medium-hard rubber or seasoned oak wood; device for demolding specimens; weights and weighing devices; glass graduates to measure the mixing water in a single operation; an electrically driven mechanical mixer equipped with paddle and mixing bowl; and trowel which shall have a steel blade with straight edges. The sand to be used shall comply with the graded sand requirement and shall be handled in such a manner as to prevent segregation. Details on preparation and assembly of specimen molds and restraining cage, proportioning and mixing of mortars, molding, and curing of specimens are discussed. The expansion and shrinkage of the test specimens at any age shall be calculated and the length-change data, expressed as linear expansion or contraction based on the length of the specimen at any time of molding, shall be reported. Bias and precision in the batch, single, and multi-laboratory operation shall also be identified.1.1 This test method covers the determination of length changes of expansive cement mortar, while under restraint, due to the development of internal forces resulting from hydration of the cement.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.3 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of this standard.1.4 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. (Warning—Fresh hydraulic cement mixtures are caustic and may cause burns to skin and tissue upon prolonged exposure.2)1.5 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.