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[求助]
the boiling water method used to measure the porisity
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The boiling method that was followed was: test samples were dried in a drying oven at 100 °C for one hour; then cooled to ambient temperature and the dry mass ݉m1 was immediately recorded to nearest 0.1 g; the samples were then placed in a beaker of distilled water and boiled for 2 h then cooled overnight in immersion liquid (water); the balance was zeroed for immersion weighing with loop or saddle for immersion test; the specimen was removed from the cooled immersion liquid and was placed onto loop or saddle and lowered into the water in position beneath the balance hook (ensuring that the specimen and saddle remain immersed during weighing and that they do not touch the sides or bottom of the vessel), the mass ݉m2 was recorded then the sample was put into another beaker of distilled water—this step was done three times for an average; to do the saturated test the specimen was withdrawn from the beaker of distilled water and quickly drained with excess water removed with a damp cloth with care taken not to touch the sample; the specimen was then placed onto the saddle or loop and suspended in air for a saturated mass ݉௦ measurement, the weight was recorded after 30 s to ensure all specimens have the same conditions. |
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