1.1 本试验方法涵盖了实验室测定砂浆或混凝土试样在约束收缩下的开裂年龄和诱导拉应力特性。该程序可用于确定砂浆或混凝土的比例和材料性能变化对干燥收缩和自收缩及水化热引起的变形引起的开裂的影响。 1.2 本试验方法不适用于膨胀材料。 1.3 本标准的文本是指提供解释性材料的注释和脚注。这些注释和脚注（不包括表格和图表中的注释和脚注）不应被视为本标准的要求。 1.4 以国际单位制或英寸-磅单位表示的值应单独视为标准值。每个系统中所述的值不一定是完全等效的；因此，为确保符合标准，每个系统应独立使用，两个系统的值不得组合。将两个系统的值结合起来可能会导致不符合标准。 1.5 本标准并不旨在解决与其使用相关的所有安全问题（如果有的话）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践，并确定监管限制的适用性。 ( 警告 --新鲜的水硬性水泥混合物具有腐蚀性，长时间接触可能会对皮肤和组织造成化学灼伤。 2. ) 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 =====意义和用途====== 5.1 本试验方法用于材料的相对比较，并不用于确定任何特定类型的结构、配置或暴露中砂浆或混凝土的开裂年龄。 5.2 本试验方法适用于最大公称尺寸为13 mm[0.5 in.]或更小的骨料混合物。 5.3 该试验方法可用于确定不同水泥混合物早期开裂的相对可能性，并有助于选择在再约束收缩下不太可能开裂的水泥基材料。实际使用中的开裂趋势取决于许多变量，包括结构类型、约束程度、性能发展速度、施工和养护方法以及环境条件。 5.4 该试验方法可用于确定材料变化对诱导拉伸应力和开裂潜力的相对影响。 这些变化可能包括但不限于骨料来源、骨料级配、水泥类型、水泥含量、含水量、补充胶结材料或化学外加剂。 5.5 对于在试验过程中没有开裂的材料，试验终止时的拉伸应力发展速率为材料的比较提供了依据。

1.1 This test method covers the laboratory determination of the age at cracking and induced tensile stress characteristics of mortar or concrete specimens under restrained shrinkage. The procedure can be used to determine the effects of variations in the proportions and material properties of mortar or concrete on cracking due to both drying shrinkage and deformations caused by autogenous shrinkage and heat of hydration. 1.2 This test method is not intended for expansive materials. 1.3 The text of this standard refers to notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of this standard. 1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. Combining values from the two systems may result in non-conformance with 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. ====== Significance And Use ====== 5.1 This test method is for relative comparison of materials and is not intended to determine the age at cracking of mortar or concrete in any specific type of structure, configuration, or exposure. 5.2 This test method is applicable to mixtures with aggregates of 13-mm [0.5-in.] maximum nominal size or less. 5.3 This test method is useful for determining the relative likelihood of early-age cracking of different cementitious mixtures and for aiding in the selection of cement-based materials that are less likely to crack under retrained shrinkage. Actual cracking tendency in service depends on many variables including type of structure, degree of restraint, rate of property development, construction and curing methods, and environmental conditions. 5.4 This test method can be used to determine the relative effects of material variations on induced tensile stresses and cracking potential. These variations can include, but are not limited to, aggregate source, aggregate gradation, cement type, cement content, water content, supplementary cementing materials, or chemical admixtures. 5.5 For materials that have not cracked during the test, the rate of tensile stress development at the time the test is terminated provides a basis for comparison of the materials.