ASTM C138 / C138M

This test method covers determination of the density of freshly mixed concrete and gives formulas for calculating the unit weight, yield or relative yield, cement content, and air content of the concrete. Yield is defined as the volume of concrete produced from a mixture of known quantities of the component materials. The test method shall use the following apparatuses: balance or scale; tamping rod, which is a round straight steel rod having the tamping end rounded to a hemispherical tip; internal vibrator which may have rigid of flexible shafts, preferably powered by electric motors; measure, which is a cylindrical container made of steel or other suitable metal specified herein; strike-off plate; mallet; and scoop of a size large enough so each amount of concrete obtained from the sampling receptacle is representative and small enough so it is not spilled during placement in the measure.

This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.

1. Scope

1.1 This test method covers determination of the density (see Note 1) of freshly mixed concrete and gives formulas for calculating the yield, cement content, and air content of the concrete. Yield is defined as the volume of concrete produced from a mixture of known quantities of the component materials.

1.2 The values stated in either inch-pound or SI units shall be regarded separately as standard. The SI units are shown in brackets. The values stated might not be exact equivalents; therefore each system must be used independently of the other.

Note 1—Unit weight was the previous terminology used to describe the property determined by this test method, which is mass per unit volume.

1.3 The text of this test method references notes and footnotes that provide explanatory information. These notes and footnotes (excluding those in tables) shall not be considered as requirements of this test method.

2. Referenced Documents

C150 Specification for Portland Cement
C172 Practice for Sampling Freshly Mixed Concrete
C188 Test Method for Density of Hydraulic Cement
C231 Test Method for Air Content of Freshly Mixed Concrete by the Pressure Method
C29/C29M Test Method for Bulk Density ("Unit Weight") and Voids in Aggregate

Index Terms

air content; cement content; concrete; relative yield; unit weight; yield; Air content--concrete; Cement content (of concrete); Concrete; Density--concrete; Gravimetric determination; Unit weight; Weight--concrete/aggregates; Yield; ICS Number Code 91.100.30; ICS Number Code 91.100.30

Citing ASTM Standards

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