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Unformatted text preview: Air Content of F reshly M ixed Concrete by the P ressure Method ASTM C-231 Tim Boyer CM 442 Pre-L ab Purpose The purpose of this lab is provide a standard method of determining the air content from freshly mixed content, excluding air in voids of aggregate particles. Equipment Air Meters Type A: measuring bowl and cover assembly; predetermined height of water above the concrete and known volume and the application of a predetermined air pressure; determine based on lowering level of water; Type B: known volume of air in sealed chamber, unknown volume of air in sample Measuring Bowl cylindrical in shape, made of steel Cover Assembly made of hard steel; fitted with a means of direct reading of the air content Calibration Vessel a measure having an internal volume equal to a percent of the volume of the measuring bowl corresponding to the approximate Spray Tube brass tube; integral part of cover assembly Trowel Tamping Rod about 16in in length Mallet Strike-Off Bar Strike-Off Plate Funnel Measure for water Vibrator Sieves Procedure...
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- Spring '08