【国外标准】 Standard Practice for Making and Curing Test Specimens for Evaluating Resistance of Coarse Aggregate to Freezing and Thawing in Air-Entrained Concrete

4.1 This practice provides standard requirements for proportioning concrete, and for preparing and conditioning test specimens suitable for evaluating the durability of coarse aggregate in air-entrained concrete subjected to freezing and thawing in accordance with Test Method C666/C666M.4.2 Concrete having an adequate air-void system may not be resistant to freezing and thawing if it contains coarse aggregate that becomes critically saturated. An aggregate particle is considered to be critically saturated when there is insufficient unfilled pore space to accommodate the expansion of water that accompanies the freezing.1.1 This practice covers procedures for making and curing test specimens for evaluating resistance of normal-weight coarse aggregates to freezing and thawing in air-entrained concrete in accordance with Test Method C666/C666M, Procedure A or B.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.3 This practice does not purport to address all 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 use.2)