Explain the rebound hammer test procedure and show the relationship between compressive strength and rebound number with hammer horizontal and vertical on dry and wet surface of concrete.

Explain the rebound hammer test procedure and show the relationship between compressive strength and rebound number with hammer horizontal and vertical on dry and wet surface of concrete.
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Rebound Hammer Test: i. Initially the plunger of rebound hammer is Kept touching to the target concrete surface ii. Then the tubular casing of hammer is pushed towards concrete, so that the spring gets wind up around the plunger iii. Now release the mass attached to plunger using dash pot, so that hammer will impact on concrete surface and rebound back depending on strength of concrete. iv. Due to backward motion of hammer, pointer on graduated scale will move in same direction. v. Observe the distance travelled by pointer/rider on graduated scale as rebound Number. vi. If this rebound Number is less, the strength of concrete will be less, But if it is more, then concrete possess sufficient strength.

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