Many concrete plants have calibrated moisture meters (based on electrical resistance or microwave technology) that continuously monitor free moisture on the aggregates and have the capability to automatically adjust the added water to maintain the mixing water content within the specified limits. Allowance should be made for water that will be absorbed by dry aggregate, however, and may be as much as 95% of its total absorption capacity during the mixing period. 1.1 This test method is used to determine the rate of absorption (sorptivity) of water by hydraulic cement concrete by measuring the increase in the mass of. Water within the aggregate particles does not affect the mixture or the w/cm. If the absorption capacity of the aggregate is known, a more common method for determining surface moisture is by drying the aggregate (ASTM C566). Standard test methods for surface moisture in fine aggregate are available (ASTM C70). How can the surface or free water carried by the aggregates be determined?Ī. Free water is simply the difference between the mass of a sample of wet-saturated aggregate and the mass of the same sample in the saturated-surface-dry condition. Standards can be obtained from appropriate standard authorities.How can the surface or free water carried by the aggregates be determined? **Please note that this test description is intentionally generic in nature and aimed at providing a descriptive summary to enhance test understanding. Water absorption is expressed as increase in weight percent. The water absorption of two ordinary concretes was determined based on the cold water, boiling water and vacuum saturation techniques. In addition to the blocks mentioned above, blocks shall be manufactured. The nominal dimensions of the concrete blocks are given below: Length : 400, 500 or 600 mm. Two inch diameter disks, 0.125" or 0.250" thick. The concrete block hollow (open or closed cavity) or solid shall be referred to by its nominal dimensions. Specimens are removed, patted dry with a lint free cloth, and weighed. The material is then emerged in water at agreed upon conditions, often 23☌ for 24 hours or until equilibrium. Immediately upon cooling the specimens are weighed. Conventional concrete specimens have high water absorption coefficient and. The data sheds light on the performance of the materials in water or humid environments.įor the water absorption test, the specimens are dried in an oven for a specified time and temperature and then placed in a desiccator to cool. Following the ASTM standard test procedure, water absorption coefficients of. Factors affecting water absorption include: type of plastic, additives used, temperature and length of exposure. Water absorption is used to determine the amount of water absorbed under specified conditions.
Water Absorption 24 Hour/Equilibrium ASTM D570
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