ASTM C25  Section 21 describes the current method for determining free moisture in hydrated lime as aspirating a slow stream of CO2-free air over the sample in a container placed inside a 115 to 120 C oven. Ensuring that the air is CO2-free involves an elaborate train of glassware containing various desiccants. Few laboratories use this configuration because of its excessive spatial, temporal and preparatory requirements. Furthermore, no precision and bias statement was prepared for this method, and one is unlikely to be written because of the tests limited use. Providing both users and manufacturers with an ASTM standard test method for the most modern, widely practiced test for free moisture of hydrated lime is clearly of benefit. The goal of this revision is to update this antiquated method with an appropriate methodology for a standard use of the more commonly used electronic moisture meter, a thermogravimetric balance.
Keywordsalternative method; aluminum; available lime index; calcium; carbon; carbon dioxide; chemical analysis; free moisture, lime; free moisture, limestone; free silica; hydrated lime; instrumental analysis; iron; limestone; loss on ignition, (LOI); magnesium; manganese; methods, classical; methods, historical; oxides; oxides, unhydrated; phosphorus; quicklime; reference method; silicon dioxide; Standard Reference Material (SRM); strontium; sulfur; Aluminum oxide (Al