6505-5 - STRENGTH TESTS ON CONCRETE (1) Compressive...

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1 STRENGTH TESTS ON CONCRETE (1) Compressive Strength Test (ASTM C 39) Basic procedure : Apply a compressive axial load to a cylindrical specimen at a prescribed rate until failure occurs. Calculate and report the compressive strength. Compressive Strength = Maximum load / Cross-sectional area of specimen Requirements for Cylindrical Test Specimens : (1) Length should be 2 times the diameter. Most commonly used: 12 inches in length & 6 inches in diameter. (2) Diameter should be at least 3 times the maximum aggregate size. (3) The ends should be ground or capped to provide smooth loading surfaces. Making cylindrical test specimens in the field Curing test specimens in a moist room
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2 Compressive strength test on a 6 x 12 inch concrete specimen (1) Compressive Strength Test (Continued) Test specimens can be: (A) Molded from freshly mixed concrete and cured in the field (ASTM C 31) or in the laboratory (ASTM C 192). (B) cored from the hardened concrete in the field (ASTM C42). (C) Made from cast-in-place cylinder molds (ASTM C873). Effect of Moisture Condition: The standard procedure requires that the specimen be tested in a moist condition. Air-dried specimens can give 20 to 25% higher compressive strength than saturated specimens. Effect of specimen diameter: For the same length-to-diameter ratio, the compressive strength decreases as the diameter increases.
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3 Effect of Length-to-Diameter Ratio: The compressive strength decreases as the L/D ratio increases. (2) Flexural Strength Test (A) Using third-point loading (ASTM C 78) Modulus of rupture, R = PL/bd 2 where P = maximum applied load (B) Using center-point loading (ASTM C 293) Modulus of rupture, R = 3PL/2bd 2
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4 Center-Point Loading Test on a Concrete Beam (2) Flexural Strength Test (Continued) Test Specimen: The standard beam is 6 in. X 6 in. in cross section. The length of the beam should be at least
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This note was uploaded on 05/26/2011 for the course CGN 6505 taught by Professor Mang during the Spring '11 term at University of Florida.

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6505-5 - STRENGTH TESTS ON CONCRETE (1) Compressive...

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