scope:

This method describes the determination of the loose uncompacted void content of a sample of coarse aggregate. When measured on any aggregate of a known grading, void content provides an indication of the aggregate's angularity, sphericity, and surface texture compared with other coarse aggregates tested in the same grading.

Three procedures are included for the measurement of void content. Two use graded coarse aggregate (standard grading or as-received grading), and the other uses several individual size fractions for void content determinations:

Standard Graded Sample (Method A)-This method uses a standard coarse aggregate grading that is obtained by combining individual sieve fractions from the maximum density curve drawn from the maximum coarse aggregate size. (See Section 8.)

Individual Size Fractions (Method B)-This method uses each of three coarse aggregate size fractions: (a) 19 mm (³/₄ in.) to 12.5 mm (¹/₂ in.); (b) 12.5 mm (¹/₂ in.) to 9.5 mm (³/₈ in.); and (c) 9.5 mm (³/₈ in.) to 4.75 mm (No. 4). For this method, each size is tested separately.

As-Received Grading (Method C)-This method uses that portion of the coarse aggregate retained on the 4.75-mm (No. 4) sieve.

This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this procedure to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to its use.

The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of R 18 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with R 18 alone does not completely assure reliable results. Reliable results depend on many factors; following the suggestions of R 18 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.