scope:

This method covers the measurement of total water content of fresh concrete. It consists of drying a test specimen of fresh concrete using a relatively high-power microwave oven within a short period of time. The difference in mass between the fresh and dry concrete test specimen will be the water content of that test specimen. Water content per unit volume of concrete can be determined by knowing the unit weight of that concrete. Unit weight shall be determined in accordance with T 121M/T 121 or ASTM C138/C138M.

This standard is applicable to both laboratory and field testing.

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 standard to establish appropriate safety and health 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.

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.