What is a 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.
Why do we do rebound hammer test?
The rebound hammer method provides a convenient and rapid indication of the compressive strength of concrete by means of establishing a suitable correlation between the rebound index and the compressive strength of concrete. The procedure of obtaining such correlation is given in 4.2.
Is the Schmidt Hammer accurate?
Thus, in a quick strength and safety assessment of existing concrete structures, the Schmidt Hammer Test is fairly reliable in determining whether the further use of the structure would still be safe, but may not be so in concluding whether the use is no longer safe.
How accurate is the 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 rebound hammer test is done?
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.
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 rebound number?
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.
What is the minimum age of concrete required for performing rebound hammer test?
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.
How do you calibrate a rebound hammer?
The cap has an adjustment screw and nut, which are used to calibrate the Rebound Hammer. 2. Using a 10 mm wrench, loosen the adjustment nut away from the cap. If the Rebound Hammer is reading low, tighten the adjustment screw (clockwise) into the cap.
How do you read rebound hammer results?
Keep the Rebound Hammer firmly pressed against the concrete surface and read the rebound number on the scale. As long as you hold the Rebound Hammer firmly against the concrete, the rebound number will remain on the scale. Record your reading.
Where can I find Valve Hammer Editor 3.x?
Originally developed with the name The Forge and distributed under the name Worldcraft on the retail Half-Life CD, Valve Hammer Editor 3.x is the official Goldsource mapping tool. The program is available on Steam (Half-Life SDK) and certain other websites.
What kind of Hammer is used for locomotive repairs?
The engineering hammer is a hard wearing durable tool which has traditionally been used for locomotive repairs and other similar activities. It has a rounded head and a cross peen which makes it ideal for particularly difficult repairs. The term is also used to describe ball peen hammers and rounded double head hammers.
What are the different types of hammers used for?
Consisting of two identical hammerhead tools this type of hammer can be used for a variety of different tasks. The railroad-spike maul hammer is a precision made tool used to hammer railroad spikes onto railroad track.
What does a hammer mean in the stock market?
A hammer occurs after a security has been declining, possibly suggesting the market is attempting to determine a bottom. The signal does not mean bullish investors have taken full control of a security, but simply indicates that the bulls are strengthening.