ASTM International Standard Test Method for Restrained Expansion of Expansive Cement Mortar ASTM C806-23

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.