Rebound hammer test rebound hammer test is done to find out the compressive strength of concrete by using rebound hammer as per is. Bartletts periodogrambased test for white noise stata. Standard test method for rebound number of hardened concrete1 this standard is issued under the. Destructive tests can provide direct information, but are relatively. Assessing the rebound hammer test for rammed earth. Around each point of observation, six readings of rebound. Rebound hammer conversion in excel concrete engineering. The rebound hammer test device usually comes with graphs prepared by the manufacturer to relate rebound to the strength of concrete. Aydin and basu, 2005 to measure the presentday in situ elastic rebound.
Rebound hammer test graph describes the correlation between the strength of concrete and rebound number. A concrete rebound hammer is the instrument used for nondestructive testing of concrete. It is also important to record the orientation of the instrument with respect to horizontal to the nearest 45 degree increment. Rebound hammer test the rebound hammer is one of the most popular nondestructive testing methods used to investigate concrete. This test is very simple and easy to run and is specified by astm c805. We also use the rebound hammer test to check out the uniformity and quality of the concrete surface.
Clean the surface of concrete, ensure the concrete is clean and dirt free. Also structures which are suspected to any strength failure are. The minimum verifiable strength the test hammer can measure is. This hardness meter in the form of a hammer device for testing concrete is based on the schmidt principal of measurement. The test can thus be conducted horizontally on vertical surfaces or vertically upwards or downwards on horizontal surfaces. Review of key issues and ideas for more reliable conclusions article pdf available in materials and structures 479.
The rebound hammer test is described in astm c805 1993, bs 1881. Its popularity is due to its relatively low cost and simple operating procedures. If it reads 80 2, the rebound hammer is calibrated. When you are finished, tighten the adjustment nut to lock the screw in this new position. 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. The rebound of an elastic mass depends on the hardness of the surface against which its mass strikes. Determination of specific gravity of fine aggregate 27. Over the years, its application has been extended to test rocks and hardness tests of paper reels. The underlying principle of the rebound hammer test is.
Rebound hammer test 10 types of factors which effect it. Proper use of the rebound hammer updated to reflect the. The rebound hammer is also one of the easiest pieces of equipment to misuse. Note the rebound hammer method can be used with greater confidence for differentiating between the questionable and acceptable parts of a structure or for relative comparison between two different structures. The surface of hardened concrete is struck with the hammer, and concrete compressive strength is estimated via the surface hardness rebound value. James instruments specalises in nondestructive testing equipment for concrete and other construction materials. Rebound number r for finding of affect of treatment test area to value of impact hammer has been each test area on the specimen adjustment as is shown in figure 1. As we already discussed the compressive strength of concrete by concrete cube test which is a destructive test worked out in the lab. Application of rebound hammer method for estimating. In each test, at least 10 test hammer impacts were performed on one. Shape tests flaky, elongation, and angularity number 29 14.
Schmidt hammer test or rebound hammer test of concrete. Testing is always done under the same test energy of 2207 j. However, it typically has the largest coefficient of variation. The rebound hammer often a schmidt hammer measures the rebound of a weight from the back of an anvil pushed against the concrete surface. For taking a measurement, the rebound hammer should be held at right angles to them surface of the concrete member. Rebound hammer test procedure for concrete hardness. Wisdot structures inspection manual part 5 chapter 18. This device is universally used because of a hardened steel hammerimpacted on the concrete by a spring. The number of test impacts required for a valid rebound number is defined in the standards.
Rebound hammer test is conducted around all the points of observation on all accessible faces of the structural element. Around each point of observation, six readings of rebound indices. Inplace test methods to estimate concrete strength has been extremely. Review of key issues and ideas for more reliable conclusions article pdf available in materials and structures 479 september 2014 with 2,956. Rebound hammer test schmidts hammer a non destructive test on concrete surface hardness test duration. Testing the strength of concrete without destructing or breaking it after hardening is a complex task. For this, the rebound hammer is tested against the test anvil made of steel having brinell hardness number of about 5000 nmm2. The rebound hammer strength test, being a nondestructive test, has its advantages of preserving integrity of sample. Onesample wilcoxon signedrank test for given median m nonparametric. Nondestructive testing of concrete by rebound hammer. Schmidt rebound hammer were made and used around the world 18. Astm c805 c805m 18 standard test method for rebound. Estimate concrete strength using rebound hammer fprimec. A rebound hammer, commonly referred to as a schmidt hammer, is a mechanical device used todirectly measure thehardness of in place concrete and the calibrated compressive.
Test anvil for concrete hammer sun labtek equipments i. Proceqs schmidt hammer portfolio is the most comprehensive available. Nondestructive testing of concrete methods of test. Push the concrete test hammer against the test surface at moderate speed until the impact is triggered. I always save my stata graphs as emf enhanced metafile. If the situation demands,the rebound hammer can be. The kinetic energy of the rebound is given by the device as the measurement of. Developed in 1948 by a swiss engineer named ernst schmidt, the device measures the hardness of concrete surfaces. Pdf assessing concrete strength with rebound hammer.
This is undoubtedly the most commonly ndt test used to quickly assess the condition of a concrete structure. Procedure for schmidt hammer test or rebound hammer test. These factors need to be considered in interpreting rebound numbers. In this test method, the ultrasonic pulse is produced by the transducer which is held in contact with one surface of the concrete member under test. Pdf rebound hammer test method statement rusi sumdaram. Concrete surfaces are thoroughly cleaned before taking any measurement. On each test sample was made 36 rebound numbers for each type of impact hammer 18 rebound number for each way preparation of test area. Guidebook on nondestructive testing of concrete structures. In order to perform the rebound hammer test, the inspector should start by. Rebound hammer test is used to estimate inplace strength if a correlation is developed. Rebound hammer has to be used against smooth and formed surface. Schmidt hammer test, hammer rebound, ultra sonic test, pulse velocity, core samples, compression strength, combined method, statistical analysis. It is not applicable for the open textured surface, i.
Standard test method for rebound number of hardened. Before starting the procedure calibration of the hammer is required. A number in parentheses indicates the year of last reapproval. 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. Always use rebound hammer perpendicular to the plane of a concrete component or any other materials. Put the rebound hammer back together, and test it on the anvil again to get a calibrated reading. Central to the improvement of the concrete infrastructure are tools that evaluate the condition of existing construction. Abrasion test 39 nondestructive testing of concrete rebound hammer test 17. This tool allows the user to get immediate results of the strength of the concrete in various parts of a floor or structure.
The method may be compared to dropping a large ballbearing onto a concrete surface. In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know and speak the laws that govern them. 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. Designate one rebound hammer for each mix design, and give the hammer to that project inspector. Standard test method for rebound number of hardened concrete. Constructed structures have to be investigated for evaluating the serviceability and safety from time to time. The individual impact points must be spaced at least 25 mm apart. Pdf the schmidt hammer in rock material characterization. The problem appears to be specific to png, as pdf and tiff show no.
Structure inspection manual part 5 nde and pde testing chapter 18 rebound hammer. Always hold the concrete rebound hammer in both hands while in use. Destructive and nondestructive testing ndt techniques are applied. The test is classified as a hardness test and based on the principle that the rebound of an elastic mass depends on the hardness of the surface against which the mass impinges. The concrete test hammer invented by ernst schmidt and introduced by proceq at the beginning of the 1950s remains to this day the most. Besides, the test is relative simple, economical and versatile compared to conventional crushing tests. A concrete with low strength and low stiffness will absorb more energy to yield in a lower rebound value. Rebound hammer conversion in excel motorcity structural 20 nov 17 18. Past produces wards dendrograms identical to those made by stata, but. Concrete test hammers swiss precision since 1954 the concrete test hammers are the most widely used portable ndt measuring instruments for a rapid assessment of the condition of a concrete structure. Statistical case study on schmidt hammer, ultrasonic and. Humboldts concrete rebound hammer provides a reliable, yet economical, alternative to the original schmidt hammer.
Estimating the strength of concrete using surface rebound value. If the rebound hammer is reading high, loosen the adjustment screw counterclockwise away from the cap. The method is widely used for testing concretes manufacturers of such rebound hammers usually provide calibrated curves showing the. However, this approach has the limitation that the correlations are valid only for. Correlation between schmidt hammer and destructive.
Test anvil for concrete hammer, rebound hammer calibration anvil, schmidt hammer test conversion chart, rebound hammer test procedure, schmidt hammer calibration anvil, rebound hammer test graph, rebound hammer test pdf, rebound hammer calibration chart. Figure 17 shows a summarizing plot in which the whole set of experimental data. A companion mechanical rebound data set was collected using a schmidt typen hammer katz et al. Rebound hammer test is done to find out the compressive strength of concrete by using rebound hammer as per is. The rebound of an elastic mass depends on the hardness of the. Request pdf nondestructive evaluation of concrete strength. The test anvil needs to be supported on a rigid base to obtain reliable rebound numbers. A schmidt hammer swiss hammer rebound hammer invented by ernst schmidt in 1948, a swiss engineer, is a mechanical device used to measure surface hardness and penetration resistance strength of.
Verification on the test anvil does not guarantee that the hammer will yield repeatable data at other points on the scale. Evaluation of the relationships between schmidt hardness. Rebound hammer test on concrete principle, procedure. Rebound hammer test schmidt hammer testing on concrete. Keep on hand 4 x 8 and 6 x 12 cylinder molds for making test specimens.
This manual contains instructions on how to use the rebound hammer and the subsequent. Save the graph named mygraph in memory to disk as an eps file graph export. In order to perform the rebound hammer test, the inspector should start by holding the instrument firmly, and ensuring that the plunger is perpendicular to the test surface. Be sure that the rebound hammer is within the standardized limits. To do this, the schmidt hammer is tested against the steel test anvil which has a brinell hardness number of about 5000mpa. Estimating the strength of concrete using surface rebound. Where a is the angle of the position of rebound hammer device. Case study of strength evaluation of structural concrete. Figure i rebound values for ntype schmidt hammer figure 2 rebound values for ltype schmidt hammer the results obtained from ntype and ltype schmidt hammers via three different test procedures as descibed earlier were illustrated in table 4 and then assessed in bar graphs in figures 1 and 2, in which the hardness rebound numbers of ntype. Procedure for rebound hammer test procedure for rebound hammer test on concrete structure starts with calibration of the rebound hammer. Then the compressive strength was ascertained on a pressure testing machine.
The schmidt hammer provides a quick and inexpensive measure of surface hardness that is widely used for estimating the mechanical properties of rock material. It is designed for testing concrete 4 100mm or more in thickness with a maximum particle size less than or equal to 1. Bureau of indian standard did not published any standard for this test upto 1991. Review of the rebound hammer method estimating concrete. The rebound values r of the sample cubes were measured using the concrete test hammer.
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