BS EN 12350-7:2009 PDF

BS EN 12350-7:2009 Testing fresh concrete. Air content. Pressure methods The suitability of any fresh concrete should be tested before it sets. BS EN 12350-7 describes two methods for testing air content of compacted fresh concrete, made with normal weight or relatively dense aggregate of maximum size up to 63 mm. The two test methods both use apparatus which employ the principle of Boyle-Mariotte's law. The two methods are: Water column method This method is when water is introduced to a predetermined height above a sample of compacted concrete. This concrete has a known volume and is in a sealed container and a predetermined air pressure is applied over the water. The reduction in volume of the air in the concrete sample is measured by observing the amount by which the water level is lowered. Pressure gauge method This method includes a known volume of air at a known pressure is merged in a sealed container with the unknown volume of air in the concrete sample. These methods do not apply to concretes made with lightweight aggregates, air cooled blast-furnace slag, or aggregates with high porosity. This is because of the magnitude of the aggregate correction factor, compared with the entrained air content of the concrete. Who will find BS EN 12350-7 useful?