ASTM C138 - 3 by rodding For those larger than 0.4ft 3...

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Unit Weight, Yield and Air Content of Concrete ASTM C-138 Tim Boyer CM 442 Pre-Lab Purpose The purpose of this lab is to provide a standard method to determine from freshly mixed concrete, the weight per cubic foot or cubic meter, the yield (the volume of concrete produced from quantities of component materials), and the air content. Equipment Balance – accurate within 0.3% of the test load Tamping Rod – about 24in long, ends with hemispherical tips Internal Vibrator – frequency of at least 7000 vibrations per minute Measure – cylindrical container made of suitable metal, volume based on nominal maximum size of coarse aggregate Strike-Off Plate – flat rectangular plate at least 1/4in thick; length and width at least 2in greater than the diameter Mallet – about 1.25 lb for measures of 0.5ft 3 or smaller; about 2.25lb for measures larger than 0.5ft 3 Procedure Compact concrete in measures smaller than 0.4ft
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Unformatted text preview: 3 by rodding For those larger than 0.4ft 3 , consolidate based on slump unless stated Rodding – place concrete in measure in three approximately 3 equal volume layers; rod each layer 25 times Internal Vibration – Fill and vibrate the measure in two approximately equal layers; insert at three different points for each layer Strike off the top surface of the concrete and finish it smoothly with the flat strike off plate Clean excess concrete from exterior of the measure and determine net weight of the concrete = = Yield Yf W1W = = Relative Yield Ry YYd = = Cement Content N N1Y = = -* Air Content A T WT 100 Post-Lab Test Conditions Test Conditions were normal for this procedure. Results Air Content: 3.0% Concrete net weight: 70.7lb Comments The procedure was followed as written and everything proceeded normally....
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ASTM C138 - 3 by rodding For those larger than 0.4ft 3...

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