ASTM C805 - Rebound Number for H a rdened Concrete ASTM...

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Unformatted text preview: Rebound Number for H a rdened Concrete ASTM C-805 Tim Boyer CM 442 P re-L ab Pu rpose The purpose of the lab is to provide a standard method to determine the rebound number for hardened concrete. Equipment Rebound Hammer consisting of a spring loaded steel hammer which when released strikes a steel plunger Abrasive Stone Test Anvil about 150mm in diameter, 150mm high P rocedure Select test surface that is at least 4in thick and r igidly supported Hold the instrument fi rmly so that the plunger is perpendicular to the test surface Gradually push the instrument toward the test surface until hammer impacts After hammer impacts, maintain pressure and lock plunger in retracted position Estimate rebound number on scale to nearest whole number Take ten readings, have no impacts closer than 1 in Discard readings more than 6 units off from average, discard data set if more than two differ that much Post-L ab Test Conditions The test conditions for this procedure were normal. Results Anvil Tests 69 75 72 74 74 74 70 73 74 74 avg 72.9 avg 31 Cylind er 28 31 30 31 34 31 30 32 33 30 Anvil Calibration Number=77 Anvil Calibration Factor=1.056 Adjusted Cylinder Number=32.74 Comments The procedure was followed as wri t ten and everything proceeded normally. ...
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ASTM C805 - Rebound Number for H a rdened Concrete ASTM...

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