What is Smith hammer test?
1. A non-destructive technique used to determine the compressive strength, surface hardness and penetration resistance of reinforced concrete and masonry structures by measuring the rebound of a spring-loaded mass impacting against the surface of the sample.
What is the Schmidt hammer test for concrete?
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 Heinrich Wilhelm Schmidt, a Swiss engineer.
How accurate is Schmidt hammer test?
Among the NDT and MDT procedures, the Schmidt, or rebound, Hammer test is largely the most commonly used worldwide. The reason for such a success is not the reliability of the tests, that may be easily showed to be less than 30%, but the simplicity of the procedure, the low price of the equipment and its easy of use.
What does a Schmidt hammer measure?
A Schmidt hammer measures the compressive strength and elastic properties of concrete and rock. A Schmidt hammer is also known as a rebound hammer or a Swiss hammer.
How is hammer test calculated?
1) The rebound hammer is tested against the anvil made of steel having a Brinell hardness of about 5000 N/mm2….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 |
Why rebound hammer test is done?
Objective of Rebound Hammer Test To determine the compressive strength of the concrete by relating the rebound index and the compressive strength. To assess the uniformity of the concrete. To assess the quality of the concrete based on the standard specifications.
Is rebound hammer test reliable?
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.
What is Schmidt hardness?
Schmidt rebound measurement device, having a scale between 0 and 100, is a most practically used device for quickly determining the in-situ and laboratory hardness of rocks, used in natural stone industry [3]. Schmidt hammer measures the distance of rebound of a controlled impact on a rock surface.
Why is a hammer test important?
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.
How does hammer test work?
The rebound hammer is a nondestructive testing apparatus, whereby the rebound of the spring driven mass is measured after its impact with concrete surface. The output of the rebound hammer is referred to as rebound number and are correlated with surface hardness of concrete.
Which quality of concrete is tested by rebound hammer?
The rebound hammer test work best for close texture concrete compared with open texture concrete. Concrete with high honeycombs and no-fines concrete is not suitable to be tested by rebound hammer. The strength is overestimated by the test when testing floated or trowelled surfaces when compared with moulded surfaces.
What are the limitations of rebound hammer test?
Limitations of Rebound Hammer Test:
- The Smoothness of the Surface:
- Size, Shape and Rigidity of the Specimen:
- Age of the Specimen:
- Surface and Internal Moisture Condition of Concrete:
- Type of Coarse Aggregate:
- Type of Cement:
- Carbonation of the Concrete Surface:
What is point load test?
Point load testing is used to determine rock strength indexes in geotechnical practice. The point load test apparatus and procedure enables economical testing of core or lump rock samples in either a field or laboratory setting.
What is core test for concrete?
Core tests are generally performed to assess whether suspect concrete in a new structure complies with strength-based acceptance criteria or not. In addition, it is critically used to determine in-place concrete strengths in an existing structure for the evaluation of structural capacity.
How do you perform a concrete hammer test?
Procedure: The instrument firmly held perpendicular to the test surface and gradually pushed toward the test surface until the hammer impact. After impact, the pressure is maintained on the instrument. The rebound number is read on the scale to the nearest whole number and recorded.
Why rebound hammer test is used?
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.