From vibration under damp matting sacks or other

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Unformatted text preview: e site at a place free from vibration, under damp matting, sacks or other similar material for 24 hours ± ½ hour from the time of adding the water to the other ingredients. The temperature of the place of storage shall be within the range of 22° to 32°C. After the period of 24 hours, they shall be marked for later identification, removed from the moulds and, unless required for testing within 24 hours, stored in clean water at a temperature of 24° to 30°C until they are transported to the testing laboratory. They shall be sent to the testing laboratory well packed in damp sand, damp sacks, or other suitable material so as to arrive there in a damp condition not less than 24 hours before the time of test. On arrival at the testing laboratory, the specimens shall be stored in water at a temperature of 27° ± 2°C until the time of test. Records of the daily maximum and minimum temperature shall be kept both during the period of the specimens remain on the site and in the laboratory. 4. SECURING AND PREPARING SPECIMENS OF HARDENED CONCRETE FOR COMPRESSION TEST 4.1 This clause deals with the procedure for securing and preparing compression test specimens obtained from hardened concrete after the concrete has been laid in position. 4.2 The test specimens shall be procured from hardened concrete according to the method described in 4 of IS : 1199-1959*. 4.3 Cores to be tested for compression strength shall have ends that are reasonably even, perpendicular to the axis and of the same diameter as the body of the specimen. A core which, before capping, has a maximum height of less than 95 percent of the diameter, or after capping, a height less than its diameter shall not be used. *Since revised. 9 IS : 516 - 1959 4.4 Capping — The ends of the specimen shall be capped before testing. The material used for the capping shall be such that its compressive strength is greater than that of the concrete in the core. Caps shall be made as thin as practicable and shall not flow or fracture before the concrete fails when the specimen is tested. The capped surfaces shall be at right angles to the axis of the specimen and shall not depart from a plane by more than 0.05 mm. The capping of specimens shall be carried out as described in 2.11. 4.5 After checking for irregularities, the core shall be placed in water at a temperature of 24° to 30°C for 48 hours before testing. The overall height of the specimens, with capping shall be measured to the nearest millimetre. 5. TEST FOR COMPRESSIVE STRENGTH OF CONCRETE SPECIMEN 5.1 This clause deals with the procedure for determining the compressive strength of concrete specimens. 5.2 Apparatus 5.2.1 Testing Machine — The testing machine may be of any reliable type, of sufficient capacity for the tests and capable of applying the load at the rate specified in 5.5. The permissible error shall be not greater than ± 2 percent of the maximum load. The testing machine shall be equipped with two steel bearing platens with...
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This document was uploaded on 10/01/2013.

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