## What is the rebound hammer test?

A Schmidt hammer, also known as a Swiss hammer or a rebound hammer or concrete hammer test, is a device to measure the elastic properties or strength of concrete or rock, mainly surface hardness and penetration resistance. It was invented by Ernst Schmidt, a Swiss engineer.

How do you find the compressive strength of a rebound hammer?

Compressive strength (N/mm2) = Maximum crushing load / Cross – sectional area of specimen. Schmidt Rebound Hammer test is a non- destructive test.

How accurate is rebound hammer test?

The results show that the compressive strength prediction using rebound hammer was accurate in the range of 48 to 58 MPa with an error of 15.32\%, but underestimates the actual strength of the samples in the upper and lower regions.

### How is hammer test calculated?

3) The test thus can be conducted horizontally on a vertical surface and vertically downwards or upwards on horizontal surfaces as shown in the figure below….Rebound Hammer Test Procedure.

Sr. No. Applications Approximate Impact Energy for Rebound Hammer in Nm
1. For Normal Weight Concrete 2.25
2. For small and impact-resistant concrete parts 0.75

How do you determine the compressive strength of concrete?

In very simple words, compressive strength is calculated by dividing the failure load with the area of application of load, usually after 28 days of curing. The strength of concrete is controlled by the proportioning of cement, coarse and fine aggregates, water, and various admixtures.

What is compressive strength test for concrete?

compressive strength test, mechanical test measuring the maximum amount of compressive load a material can bear before fracturing. The test piece, usually in the form of a cube, prism, or cylinder, is compressed between the platens of a compression-testing machine by a gradually applied load.

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## How accurate is the rebound hammer test?

The accuracy of the rebound hammer result may differ from ±25\% to the compressive strength of concrete by the destructive test method. From the above graph, you may see the relationship between the rebound number and the compressive strength of concrete.

How to measure compressive strength of concrete with rebound number?

The most suitable method of obtaining the correlation between compressive strength of concrete and rebound number is to test the concrete cubes using compression testing machine as well as using rebound hammer simultaneously.

What is a concrete rebound hammer?

A Concrete Rebound Hammer is also referred to as a Swiss Hammer, Schmidt Hammer, or just Concrete Test Hammer which is an instrument that is easily the most commonly used (and misused) device for testing hardened concrete. If playback doesn’t begin shortly, try restarting your device.

### Can rebound values be used as a basis to reject concrete?

It is important to note that ASTM C805 states that rebound values cannot be used as the basis to accept or reject concrete. Pushing the test hammer’s piston against the surface of hardened concrete loads a spring mechanism until it trips and releases a hammer mass.

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