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The Figg test measures water permeability in a 5.5 mm-diameter hole drilled 30 mm into the concrete. The top of the hole is plugged using silicone sealant. A double-skinned hypodermic needle is inserted into the hole through the plug and water is introduced into the drill hole through the inner needle using a syringe. The water flows back up the outer needle and into a horizontal length of capillary tube fitted with a scale. The capillary tube is set at a level of 100 mm above the bottom of the hole. To carry out the test, the valve to the syringe is closed and the time taken for the water meniscus in the capillary tube to travel 50 mm is recorded.
The equipment can be adapted to give a measure of air permeability. A vacuum pump is used to reduce the pressure in the hole to 15 kPa and a manometer is used in place of the capillary tube. The time for the pressure in the hole to rise by 5 kPa after the valve to the vacuum pump is closed is measured.
Acknowledgement: The Concrete Society
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