1.1 本试验方法包括测定相对密度（比重）和细骨料的吸收。相对密度（比重）是一种无量纲质量，表示为烘干（OD）、饱和表面干燥（SSD）或表观相对密度（重力）。OD相对密度在骨料干燥后测定。SSD相对密度和吸收是在将骨料浸泡在水中规定时间后测定的。 1.2 本试验方法不适用于符合规范要求的轻质骨料 第332页 I组骨料。 1.3 以国际单位制表示的值应视为标准值。本标准不包括其他测量单位。 1.4 本测试方法的文本引用了提供说明材料的注释和脚注。这些注释和脚注（不包括表和图中的注释和脚注）不应视为本试验方法的要求。 1.5 本标准并不旨在解决与其使用相关的所有安全问题（如有）。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。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《国际标准、指南和建议制定原则决定》中确立的国际公认标准化原则制定的。 =====意义和用途====== 5.1 相对密度（比重）是指骨料的质量与等于骨料颗粒体积的水的质量之比，也称为骨料的绝对体积。 它也表示为骨料颗粒的密度与水的密度之比。通过试验方法确定骨料颗粒密度和骨料体积密度之间的区别 29米/29米 ，包括骨料颗粒之间空隙的体积。 5.2 相对密度用于计算包含骨料的各种混合物中骨料所占的体积，包括水硬性水泥混凝土、沥青混凝土和其他基于绝对体积进行配比或分析的混合物。相对密度（比重）也用于计算试验方法中骨料中的空隙 29米/29米 和测试方法 第1252页 相对密度（比重）（SSD）用于通过试验方法中的水置换法测定细骨料表面水分 C70型 如果骨料处于饱和表面干燥状态，即满足其吸收，则使用相对密度（比重）（SSD）。或者，当骨料干燥或假设干燥时，使用相对密度（比重）（OD）进行计算。 5.3 表观相对密度（比重）与构成组成颗粒的固体材料有关，不包括颗粒内可接触到水的孔隙空间。 该值未在建筑骨料技术中广泛使用。 5.4 如果认为骨料与水接触的时间足以满足大部分吸收潜力，则吸收值用于计算与干燥条件相比，由于在组成颗粒内的孔隙空间中吸收的水而导致的骨料材料质量的变化。吸收的实验室标准是将干骨料浸没规定时间后获得的标准。如果在使用前没有机会干燥，则从地下水位以下开采的骨料的含水量通常大于本试验方法测定的吸水率。 相反，一些骨料在使用前未持续保持潮湿状态，其吸收的水分可能少于24小时浸泡状态。对于与水接触并在颗粒表面具有自由水分的骨料，通过从试验方法确定的总含水量中扣除吸收量来确定自由水分的百分比 第566页 通过干燥。 5.5 本试验方法中描述的一般程序适用于测定除24- h浸泡，如沸水或真空饱和。通过其他试验方法获得的吸收值将不同于通过规定的24小时浸泡获得的值，相对密度（比重）（SSD）也不同。

1.1 This test method covers the determination of relative density (specific gravity) and the absorption of fine aggregates. The relative density (specific gravity), a dimensionless quality, is expressed as oven-dry (OD), saturated-surface-dry (SSD), or as apparent relative density (specific gravity). The OD relative density is determined after drying the aggregate. The SSD relative density and absorption are determined after soaking the aggregate in water for a prescribed duration. 1.2 This test method is not intended to be used for lightweight aggregates that comply with Specification C332 Group I aggregates. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 The text of this test method references 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 test method. 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. 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 Relative density (specific gravity) is the ratio of mass of an aggregate to the mass of a volume of water equal to the volume of the aggregate particles – also referred to as the absolute volume of the aggregate. It is also expressed as the ratio of the density of the aggregate particles to the density of water. Distinction is made between the density of aggregate particles and the bulk density of aggregates as determined by Test Method C29/C29M , which includes the volume of voids between the particles of aggregates. 5.2 Relative density is used to calculate the volume occupied by the aggregate in various mixtures containing aggregate including hydraulic cement concrete, bituminous concrete, and other mixtures that are proportioned or analyzed on an absolute volume basis. Relative density (specific gravity) is also used in the computation of voids in aggregate in Test Method C29/C29M and in Test Method C1252 . Relative density (specific gravity) (SSD) is used in the determination of surface moisture on fine aggregate by displacement of water in Test Method C70 . Relative density (specific gravity) (SSD) is used if the aggregate is in a saturated surface-dry condition, that is, if its absorption has been satisfied. Alternatively, the relative density (specific gravity) (OD) is used for computations when the aggregate is dry or assumed to be dry. 5.3 Apparent relative density (specific gravity) pertain to the solid material making up the constituent particles not including the pore space within the particles that is accessible to water. This value is not widely used in construction aggregate technology. 5.4 Absorption values are used to calculate the change in the mass of an aggregate material due to water absorbed in the pore spaces within the constituent particles, compared to the dry condition, if it is deemed that the aggregate has been in contact with water long enough to satisfy most of the absorption potential. The laboratory standard for absorption is that obtained after submerging dry aggregate for a prescribed period of time. Aggregates mined from below the water table commonly have a moisture content greater than the absorption determined by this test method, if used without opportunity to dry prior to use. Conversely, some aggregates that have not been continuously maintained in a moist condition until used are likely to contain an amount of absorbed moisture less than the 24–h soaked condition. For an aggregate that has been in contact with water and that has free moisture on the particle surfaces, the percentage of free moisture is determined by deducting the absorption from the total moisture content determined by Test Method C566 by drying. 5.5 The general procedures described in this test method are suitable for determining the absorption of aggregates that have had conditioning other than the 24-h soak, such as boiling water or vacuum saturation. The values obtained for absorption by other test methods will be different than the values obtained by the prescribed 24-h soak, as will the relative density (specific gravity) (SSD).