【国外标准】 Standard Specification for Rapid Hardening Hydraulic Cement

This specification covers performance requirements for rapid hardening hydraulic cements. There are no restrictions on the compositions of the cement or its constituents. The specification classifies cements by type based on specific requirements for very early compressive strength development. The following are the four types of rapid hardening cement: (1) Type URH, ultra rapid hardening for use where high early strength is desired; (2) Type VRH, very rapid hardening for use where very high early strength is desired; (3) Type MRH, medium rapid hardening for use where mid-range hardening high early strength is desired; and (4) Type GRH, general rapid hardening for use when the higher strength properties of a Type VRH or a Type MRH cement is not required. Cement of the type specified shall conform to all of the applicable standard physical requirements for compressive strength and drying shrinkage. Cement shall be tested using the following methods: autoclave expansion; time of setting; compressive strength; drying shrinkage of mortar; heat of hydration; surface resistance; alkali silica resistivity; and expansion in water.1.1 This specification is for rapid hardening hydraulic cements. This is a specification giving performance requirements. There are no restrictions on the composition of the cement or its constituents.1.2 The specification classifies cements by type based on specific requirements for very early compressive strength development.1.3 The values stated in either SI units or inch-pound units shall be regarded separately as standard. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.1.4 The text of this standard refers to notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) are not requirements of the standard.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. (Warning—Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure.2)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.