ASTM C128-15 PDF Download

ASTM C128-15 is a standard test method that determines the relative density (specific gravity) and absorption of fine aggregates. Relative density is the ratio of the mass of an aggregate to the mass of a volume of water equal to the volume of the aggregate particles. It is also expressed as the ratio of the density of the aggregate particles to the density of water. This test method distinguishes between the density of aggregate particles and the bulk density of aggregates, including the volume of voids between the particles.

Relative density is used to calculate the volume occupied by the aggregate in various mixtures, such as hydraulic cement concrete and bituminous concrete. It is also used in the computation of voids in aggregate and in the determination of surface moisture on fine aggregate. The test method provides options for determining relative density in different conditions, such as saturated surface-dry condition or dry condition.

The standard also covers the absorption of aggregates, which is the change in mass of an aggregate material due to water absorbed in the pore spaces within the constituent particles. Absorption values are used to calculate the moisture content of aggregates. The absorption test is conducted by submerging the dry aggregate for a prescribed period of time. Different conditioning methods, such as boiling water or vacuum saturation, may yield different absorption values.

It is important to note that the test method is not intended for lightweight aggregates that comply with a separate specification. Explanatory notes and footnotes provided in the text are not considered requirements of the test method.