Standard Test Method for Water Content in Fresh Cementitious Mixtures by Rapid Evaporation

Importancia y uso:

5.1 This test method provides a procedure to determine the total water content in a sample of a fresh hydraulic cementitious mixture by determining the change in mass of the sample after rapid evaporation using a furnace capable of maintaining an air temperature between 790 °C and 815 °C [1450 °F and 1500 °F]. While this is the furnace temperature, the temperature of the sample is lower and this does not cause aggregates to decompose, which could contribute to mass loss during the test. This method is applicable under laboratory or field conditions.

5.2 This test method is applicable to samples of fresh grout, mortar, or concrete covered under the scope of this standard, with nominal maximum aggregate size up to 50 mm [2.0 in.].

5.3 The water absorbed by the coarse and fine aggregate in the batch is based on the absorption of each aggregate determined in accordance with Test Method C127 and Test Method C128. The percentage of each aggregate type is determined from the mixture design or from the batch record. The aggregate content as a percentage of the concrete mixture can be determined based on either the saturated-surface-dry (SSD) or oven-dry (OD) condition, because this has little effect on the estimate of the amount of water absorbed by the aggregates.

5.4 The measured water content can be used to calculate the w/cm of the batch. The calculated value of w/cm will depend on the following required information about the batch:

5.4.1 Cementitious materials content,

5.4.2 Total mass of concrete in the mixture design,

5.4.3 Density of the sample determined in accordance with Test Method C138/C138M,

5.4.4 Quantity of each aggregate, and

5.4.5 The absorption of each aggregate.

Note 2: For ready-mixed concrete, the composition of the concrete can be obtained from the delivery ticket, or the mixture proportions can be requested from the producer. Batched quantities of aggregates on the delivery ticket are typically reported as mass of wet aggregates and corrections to the SSD or OD condition may be needed to estimate absorbed water.

5.5 This test method can be used to monitor batch-to-batch variability of mixing water content of concrete or other cementitious mixtures.

Subcomité:

C09.60

Volúmen:

04.02

Palabras clave:

absorbed water; rapid evaporation; water content; water-cementitious material ratio.;