Значение и использование 4. Significance and UseNumerous properties of cementitious materials are controlled by their initial hydration rate. Examples include early-age strength development, heat release, and crack resistance. One direct and convenient measure of this initial hydration rate is provided by the measurement of the chemical shrinkage of the cement paste during its hydration. As cement hydrates, the hydration products occupy less volume than the initial reacting materials (cement and water). Due to this volume change, a hydrating cement paste will sorb water from its immediate surroundings, when available. At early times, this sorption is in direct proportion to the amount of hydration that has occurred.⁴ This method is based on the one developed by Geiker.⁵ The results are relevant to understanding the hydration behavior of cements. This method does not measure the bulk volume changes (autogenous shrinkage) associated with chemical shrinkage nor the cracking potential of concretes produced with the evaluated cement. Область применения

1.1 This test method measures the internal (absolute) volume change of hydraulic cement paste that results from the hydration of the cementitious materials. This volume change is known as chemical shrinkage .

1.1.1 Procedure A, volumetric method.

1.1.2 Procedure B, the density method.

1.2 The values stated in SI units are to be regarded as the standard.

1.3 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. (Warning—Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure.²)