Rebound hammer test by varun and rachana vnit,nagpur duration. Betonprufhammer bedienungsanleitung sclerometre a beton nnr. Proper use of the rebound hammer updated to reflect the. The individual impact points must be spaced at least 25 mm apart. Rebound hammer test is conducted around all the points of observation on all accessible faces of. Isrm suggested method for determination of the schmidt hammer rebound hardness. Rebound hammer test schmidt hammer testing on concrete. The method is widely used for testing concretes manufacturers of such rebound hammers usually provide calibrated curves showing the. Rebound hammer test on concrete principle, procedure. Astm c805, standard test method for rebound number of hardened concrete, summarizes the procedure as a steel hammer impacts, with a predetermined amount of energy, a steel plunger in contact with a surface of concrete, and the distance that the hammer rebounds is measured. Rebound hammer test is a nondestructive testing method of concrete which provide a convenient and rapid indication of the rebound hammer test is a nondestructive testing method of concrete. Objective determine compressive strength of concrete by using rebound schmidt hammer. Mentioned are the principle, procedure, advantages and disadvantages of rebound hammer.
The same restriction applies to the pulse velocity method per astm c597. To perform a test, make sure the piston is extended and gently press the. Apr 16, 2019 rebound hammer test relates one concrete element with other concrete elements in terms of quality. Rebound hammer is also known as schmidts hammer or swiss hammer as it is invented by ernst schmidt, a swiss engineer. Estimating the strength of concrete using surface rebound. The scmidt hammer test is based on the elastic rebound of hammer which presses on concrete surface and it measures the surface hardness of concrete. Schmidt hammer test, hammer rebound, ultra sonic test, pulse velocity, core samples, compression strength. Standard test method for rebound number of hardened concrete1. The rebound hammer measurements results in figure 4. Concrete inspection rebound hammer elcometer 181 analogue concrete test hammer standards. For taking a measurement, the rebound hammer should be held at right angles to them surface of the concrete member. Statistical case study on schmidt hammer, ultrasonic and core.
If the situation demands, the rebound hammer can be held at intermediate angles also, but in each case, the rebound number will be different for the same concrete. These factors need to be considered in interpreting rebound numbers. Before starting the procedure calibration of the hammer is required. Nondestructive testing of concrete by rebound hammer. If it reads 80 2, the rebound hammer is calibrated. Statistical case study on schmidt hammer, ultrasonic and.
The rebound hammer, developed by ernst schmidt, provides an inexpensive and quick method for nondestructive testing and evaluation of the hardness of concrete. Schmidt hammer test or rebound hammer test of concrete. Procedure to determine strength of hardened concrete by rebound hammer. In 1948, a swiss engineer, ernst schmidt developed a test hammer for measuring the hardness of concrete by the rebound principle description the hammer consists of a spring controlled mass that slides.
Test procedure the reading is very sensitive due to local variation in the concrete, especially to aggregate particles near to the surface. Nondestructive testing of concrete methods of test. Digital functions allow greater number of test, leading to better quality tests. Hammer type, test range and calibration the earlier isrm suggested method 1 endorsed the use of only the ltype sh. Principles of the rebound hammer ernst schmidt, a swiss engineer, developed the modern rebound hammer in 1948. Rebound hammer rebound hammer a handy nondestructive testing instrument should be cheap, easy to operate and should have reproducibility for, fairly accurate results. Pdf application of rebound hammer method for estimating. Before knowing the procedure learn how schidmt hammer.
After traversing a known path length q in the concrete, the pulse of vibrations is converted into an electrical signal by the second. Figure 1 presents an example of a school built with re in france. Rebound hammer test on concrete principle, procedure duration. Sep 19, 2014 rebound hammer test rebound hammer test is done to find out the compressive strength of concrete by using rebound hammer as per is. Rebound hammer test on concrete we civil engineers. The rebound number may be used to assess the uniformity of concrete in situ and to delineate areas of poor quality or deteriorated concrete. The manual concrete test hammer, aka rebound hammer, schmidt hammer, swiss hammer, sclerometer, is the most widely used non destructive instrument for compressive strength determination. Moreover, we will discuss how to estimate concrete strength using rebound hammer. Standard test method for rebound number of hardened concrete. The rebound hammer test has been around since 1940s and today is a commonly used method for estimating the compressive strength of in place concrete. Jul 09, 2019 the rebound hammer, developed by ernst schmidt, provides an inexpensive and quick method for nondestructive testing and evaluation of the hardness of concrete. Reliability of rebound hammer test in concrete compressive.
Impact energy for rebound hammer for different applications. In addition, influence of test conditions and some general guidance on the interpretation of test results are also given. James instruments specalises in nondestructive testing equipment for concrete and other construction materials. Rebound hammer against the concrete surface to be tested.
An empirical relationship has been determined between the a absorbed by the concrete when given a high impact and its compressive. Besides, the test is relative simple, economical and versatile compared to conventional crushing tests. The instrument firmly held perpendicular to the test surface and gradually pushed toward the test surface until the hammer impact. All concrete test hammers measure the surface hardness of the material they are testing.
Put the rebound hammer back together, and test it on the anvil again to get a calibrated reading. Review of the rebound hammer method estimating concrete. Part 2 rebound hammer 1 scope this standard covers the object, principle, apparatus and procedure of rebound hammer test method. Developed in 1948 by a swiss engineer named ernst schmidt, the device measures the hardness of concrete surfaces. This device is universally used because of a hardened steel hammerimpacted on the concrete by a spring. Destructive tests can provide direct information, but are relatively. Rebound hammer test, schmidt hammer test, nondestructive. Rebound hammer test nondestructive testing hardness. The number of test impacts required for a valid rebound number is defined in the standards. The rebound hammer test is based on the principle that the rebound of an elastic mass depends on the hardness of the surface against which the mass impinges. Aug 09, 2017 rebound hammer test on concrete principle, procedure duration.
Pdf the rebound hammer strength test, being a nondestructive test, has its advantages of preserving integrity of sample. The procedure is repeated until the wall is completed. Standard test method for determination of rock hardness by. In the procedure of rebound hammer test, the plunger of rebound hammer is pressed on the surface of concrete, so that a spring controlled mass with a constant energy is made to hit the concrete. Keep adjusting and testing the rebound hammer until it reads 80 2. The rebound hammer is also called as schmidt hammer that consist of a spring controlled mass that slides on a plunger within a tubular housing. The rebound hammer test is one of the nondestructive tests used to check the compressive strength of concrete.
Rebound hammer test is a nondestructive testing method of concrete which provide a convenient and rapid indication of the compressive strength of the concrete. Application of rebound hammer method for estimating. The rebound of an elastic mass depends on the hardness of the surface against which its mass strikes. This procedure is recommended in all guidelines and relevant international standards. Operating principle of the rebound hammer physical principle the test hammer rebound hammer is intended to.
Conforms to astm c805 and other international standards. The investigation was conducted on 150mm concrete cubes which were cured for 28 days before the exposures. The rational use of the various available methods, as well as a possible combination of more than one method, can be particularly interesting from the viewpoint of the validity of results. Before commencement of a test, the rebound hammer should be tested against the test anvil, to get reliable results, for which the manufacturer of the rebound hammer indicates the range of readings on the anvil suitable for different types of rebound hammer. Asphalt strength testing with a rebound hammer although the silverschmidt is mainly used to verify concrete compressive strength, it can also be employed in the verification of other materials. Typically, a rebound hammer will result in a rebound number of 80 2 when tested on the anvil described in. Push the concrete test hammer against the test surface at moderate speed until the impact is triggered. The surface of hardened concrete is struck with the hammer, and concrete compressive strength is estimated via the surface hardness rebound value. Concrete rebound hammer test was first covered by is 311 part 2 1992. Since the test is very sensitive to the presence of aggregates and voids at the concrete surface, it is necessary to take more than 10 readings over the area of test. Digital test hammers for the quick and easy determination of the strength of concrete, and hardness of construction materials.
Generally, rebound hammer test method can be used to differentiate the acceptable and questionable parts of the concrete structure or to. We use the rebound hammer to get an indication of the concrete. Guidebook on nondestructive testing of concrete structures. Jun 05, 20 the concrete test hammer invented by ernst schmidt and introduced by proceq at the beginning of the 1950s remains to this day the most widely used nondestructive test instrument for a rapid. Pdf rebound hammer test method statement rusi sumdaram. Rebound hammer test is the most appropriate and useful testing methods for comparing the relatively weaker and stronger areas of concrete.
If the readings fall outside of this range, take the rebound hammer apart and try to adjust it again. Central to the improvement of the concrete infrastructure are tools that evaluate the condition of existing construction. Operating principle of the rebound hammer physical principle the test hammer rebound hammer is intended to measure the surface hardness of concrete and there is an. The rebound is read off along a graduated scale and designation as the rebound number of rebound index. The concrete test hammer invented by ernst schmidt and introduced by proceq at the beginning of the 1950s remains to this day the most widely used nondestructive test instrument for a rapid. Rebound hammer test procedure for concrete hardness. To do this, the schmidt hammer is tested against the steel test anvil which has a brinell hardness number of about 5000mpa. Aug 05, 2018 procedure for schmidt hammer test or rebound hammer test. Rebound hammer test 10 types of factors which effect it. Destructive and nondestructive testing ndt techniques are applied. In 1948, a swiss engineer, ernst schmidt developed a test hammer for measuring the hardness of concrete by the rebound principle.
In each test, at least 10 test hammer impacts were performed on one. The strength estimation of concrete on the basis of its surface hardness dates back more than 100 years 1. Silverschmidt type l with a mushroom plunger is often utilized to measure the asphalt strength of newly built and repaired roads before opening them. Rebound hammer test by varun and rachana vnit,nagpur. If the situation demands,the rebound hammer can be. Estimate concrete strength using rebound hammer fprimec. Besides, the test is relative simple, economical and versatile compared to. The rebound hammer has been around since the late 1940s and today is a commonly used method for estimating the compressive strength of inplace concrete. The rebound hammer is also one of the easiest pieces of equipment to misuse.
This article is to discuss the rebound hammer and how to successfully use it to evaluate concrete. However, despite its apparent simplicity, the rebound hammer test involves complex problems of impact and the associated stresswave propagation. Aug 24, 2016 the rebound hammer test is based on the principle that the rebound of an elastic mass depends on the hardness of the surface against which the mass impinges. Rebound hammer l rebound hammer test i schmidt hammer i. Assessing the rebound hammer test for rammed earth. Oct 29, 2016 the rebound hammer is also one of the easiest pieces of equipment to misuse. The test can thus be conducted horizontally on vertical surfaces or vertically upwards or downwards on horizontal surfaces. Schmidt hammer test, hammer rebound, ultra sonic test, pulse velocity, core samples, compression strength, combined method, statistical analysis. Calibration and reliability of the rebound schmidt hammer test. Swiss engineer ernst schmidt is the name of the scientist who first introduced rebound hammer test, and it is also called as schmidt hammer test or swiss hammer test. The rebound values r of the sample cubes were measured using the concrete test hammer. Bureau of indian standard did not published any standard for this test upto 1991. Astm c805, standard test method for rebound number of hardened concrete, summarizes the procedure as a steel hammer impacts, with a predetermined.
Rebound hammer test rebound hammer test is done to find out the compressive strength of concrete by using rebound hammer as per is. Then the compressive strength was ascertained on a pressure testing machine. We use this test to differentiate the questionable and acceptable parts of the structure or base on its strength comparison between two different structures. The test anvil needs to be supported on a rigid base to obtain reliable rebound numbers. Rebound hammer test relates one concrete element with other concrete elements in terms of quality. Standard test method for rebound number of hardened.
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