Rebound Hammer for Non Destructive Testing of Concrete

Importance and Rebound Hammer Test:

It is often necessary to test concrete structures after the concrete has hardened to determine whether the structure is suitable for its proposed use. Such testing should ideally be done without damaging the structure. Rebound hammer is used for compressive strength of concrete (as per IS-13311(Part-2)/92). Arbro offers a single point solution of testing of concrete and other building and construction materials. Contact us today using the Quick Query form on the right, to have our representative contact and visit you to provide you a solution for your lab testing needs. 

Apparatus:

Rebound hammer consists of a spring-loaded steel hammer that when released strikes a steel plunger in contact with the concrete surface .The spring-loaded hammer travels with a consistent and reproducible velocity .The rebound distance of the steel hammer for the steel plunger is measured on a linear scale attached to the frame of the instrument.

Principle of test:

When the plunger of instrument is pressed against the surface of the concrete, the spring controlled mass rebound and the extent of such rebound depends upon the surface hardens of concrete .The surface hardness and therefore the rebound is taken to be related to the compressive strength of the concrete .The rebound is read off along a graduated scale and designation as the rebound number of rebound index.

Procedure:

The instrument firmly held perpendicular to the test surface and gradually pushed toward the test surface until the hammer impact. After impact, pressure is maintained on the instrument. The rebound number is read on the scale to the nearest whole number and recorded.

Concrete Age:

The concrete should be 14 to 56 days old. Should be tested after the outer surface has been ground down 0.25 to 0.5 inch.

Surface condition:

The surface of the concrete at the point tested must be smooth, dry and free of honeycombing. 

Interpretation of results:

Average Rebound Number

Quality of Concrete

› 40

Very Good

30-40

Good

20-30

Fair

<20

Poor and/or delaminated

0

Very poor/or delaminated

 

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