Rebound Hammer Test
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REBOUND HAMMER
Rebound hammer test is done to find out the compressive strength of concrete by using rebound hammer as per IS: 13311 (Part 2) – 1992. The underlying principle of the rebound hammer test is
The rebound of an elastic mass depends on the hardness of the surface against which its mass strikes. When the plunger of the rebound hammer is pressed against the surface of the concrete, the pring-controlled mass rebounds and the extent of such a rebound depends upon the surface hardness of the concrete. The surface hardness and therefore the rebound is taken to be related to the compressive strength of the concrete. The rebound value is read from a graduated scale and is designated as the rebound number or rebound index. The compressive strength can be read directly from the graph provided on the body of the hammer.
Procedure to determine strength of hardened concrete by rebound hammer.
i) Before commencement of a test, the rebound hammer should be tested against the test anvil, to get reliable results, for which the manufacturer of the rebound hammer indicates the range of readings on the anvil suitable for different types of rebound hammer.
ii) Apply light pressure on the plunger – it will release it from the locked position and allow it to extend to the ready position for the test.
iii) Press the plunger against the surface of the concrete, keeping the instrument perpendicular to the test surface. Apply a gradual increase in pressure until the hammer impacts. (Do not touch the button while depressing the plunger. Press the button after impact, in case it is not convenient to note the rebound reading in that position.)
iv) Take the average of about 15 readings.
Interpretation of Results
The rebound reading on the indicator scale has been calibrated by the manufacturer of the rebound hammer for horizontal impact, that is, on a vertical surface, to indicate the compressive strength. When used in any other position, appropriate correction as given by the manufacturer is to be taken into account.
Dear Sir,
Please send the procedure on how to calculate the rebound hammer result obtained at site to get the concrete strength result, calculation procedures with example, and BS specifications on various concrete strength.
Thanks for your help.
Dear Sir,
Please send the procedure on how to calculate the rebound hammer result obtained at site to get the concrete strength result, calculation procedures with example, and BS specifications on various concrete strength.
Thanks for your help
Dear Sir,
i want to ask,
is the result with hammer test is ’same’ with the result with crushing machine(Universal testing machine)?
i have done my research with hammer test but the result is less 10-15% than crushing machine.
my test using cube 15 x 15 x 15 cm, and 144 cube ive been compare with utm (crushing machine).
thanks a lot b4
regards
arif
Dear sir/madam,
Please send the procedure on how to calculate the rebound hammer result obtained at site to get the 28 days concrete Compressive strength result, calculation procedures with example, and BS specifications on various concrete strength.
Thanks for your help
Dear Sir/Madam,
Pls. let me know the possible tolerrance of a particular reading, obtained using Rebound Hammer. (for eg. if the strength of a concrete is read as 38 N/mm2, using the rebound hammer, what will be the range it might vary, when a core sample of same concrete, is crushed in a Compressive Strength testing machine ? )
Please send the procedure on how to calculate the rebound hammer result obtained at site to get the concrete strength result