Assessing the rebound hammer test for rammed earth. Rebound hammer test is done to find out the compressive strength of concrete by using rebound hammer as per is. Schmidt hammers, or concrete test hammers, are used to determine inplace strength of concrete. The schmidt hammer rebound test was developed to determine the compressive strength of concrete, and has been used to determine the hardness and compressive strength of rock material isrm 1978a. Keep adjusting and testing the rebound hammer until it reads 80 2. 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. For taking a measurement, the rebound hammer should be held at right angles to them surface of the concrete member. Review of the rebound hammer method estimating concrete. Some factors that may affect the results of the test include. Rock at 0 c or less may exhibit very high rebound values. Ltd anamnagar, kathmandu may, 2015 introduction the proposed samundratar bridge is under construction at samundratar vdc.
Over the years, its application has been extended to test rocks and hardness tests of paper reels. The rebound hammer test is one of the nondestructive tests used to check the compressive strength of concrete. The rebound hammer test is codified in astm c805 3 and csn en 125042 4. If the situation demands,the rebound hammer can be.
To find the quality of concrete in relation to standard requirement. The manufacturer shall report the rebound number to be obtained by a properly operating instrument when tested on an. Test can be undertaken on site and the number of test is unlimited. Pdf application of rebound hammer method for estimating.
The rebound is read off along a graduated scale and designation as the rebound number of rebound index. Nondestructive testing of concrete by rebound hammer. 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. Nondestructive testing of concrete methods of test. However, this approach has the limitation that the correlations are valid only for. Rebound hammer for non destructive testing of concrete.
Concrete rebound hammer original schmidt os8000 less coring, with concrete strength and uniformity evaluation using rebound hammer technology schmidt hammers by proceq, the inventor of rebound hammer technology, have long been the global benchmark for nondestructive compressive strength estimation, and make it possible to drastically. However, it typically has the largest coefficient of variation. When the plunger of the rebound hammer is pressed against the surface of the concrete. Standard test method for determination of rock hardness by.
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. Impact energy for rebound hammer for different applications. 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. When the plunger of rebound hammer is pressed against the surface of the concrete, the. Rebound hammer is a springloaded steel hammer that, when. Rebound hammer test procedure for concrete hardness. It is hoped that this instruction manual will serve to orient the students in performing the test and preparing the report as per the codal provision. 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. If the readings fall outside of this range, take the rebound hammer apart and try to adjust it again. Test procedure is simple and equipment is portable and easy to operate. Typically, a rebound hammer will result in a rebound number of 80 2 when tested on the anvil described in. Introduction the rebound hammer test is the most popular method to measure the surface hardness of a concrete mass.
Part 2 rebound hammer 1 scope this standard covers the object, principle, apparatus and procedure of rebound hammer test method. 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. The rebound of an elastic mass depends on the hardness of the surface against which its mass strikes. If it reads 80 2, the rebound hammer is calibrated.
The test can thus be conducted horizontally on vertical surfaces or vertically upwards or downwards on horizontal surfaces. Besides, the test is relative simple, economical and versatile compared to. The surface of hardened concrete is struck with the hammer, and concrete compressive strength is estimated via the surface hardness rebound value. Estimate concrete strength using rebound hammer posted on july 9, 2019 inplace test methods to. Always hold the concrete rebound hammer in both hands while in use. Estimating the strength of concrete using surface rebound. Standard test method for rebound number of hardened concrete. An empirical relationship has been determined between the a absorbed by the concrete when given a high impact and its compressive.
View 20191112 schmidt hammer test method statement. Concrete strength test rebound hammer original schmidt live. For most concrete surfaces, the finish is usually sufficiently smooth to ensure good acoustical contact by. Is schmidt hammer test a standard test for testing concrete strength.
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. To assess the likely compresive strength of concrete by using rebound hammer as per is. Rebound hammer test on concrete we civil engineers. Acceptability of rebound hammer test is evaluated by different research works and studies. Doc rebound hammer test result prince patwa academia.
Besides, the test is relative simple, economical and versatile compared to conventional crushing tests. Jun 10, 2016 the hm75 schmidt concrete rebound test hammer provides rapid nondestructive estimates of inplace concrete strength and is a valuable tool when assessing the need for further testing. Moreover, the best part of rebound hammer test is concrete can be tested in real time at the site instead of going to the lab without any damage. This device is universally used because of a hardened steel hammerimpacted on the concrete by a spring. Rebound hammer is also known as schmidts hammer or swiss hammer as it is invented by ernst schmidt, a swiss engineer. 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.
The schmidt hammer rebound hardness test is a simple and nondestructive test originally developed in 1948 for a quick measurement of ucs 1, and later was extended to estimate the hardness and strength of rock 2, 3. Description a rebound hammer provides a method for assessing the insitu. In addition, influence of test conditions and some general guidance on the interpretation of test results are also given. The device used in the test known as schmidt hammer or rebound hammer, uses a spring and measures the hardness of concrete surface using the rebound principle 2. The hammer and materials to be tested should be at the same temperature. Rebound hammer test nondestructive testing hardness. Oct 28, 2014 lab report gis and rs 2012ge56 16 if the concrete does not form part of a large mass any movement caused by the impact of the hammer will result in a reduction in the rebound number. However, this approach has the limitation that the correlations are valid only for the materials and mix proportions used in trials. The data used for this lab report was not gathered from the student run experiments, but rather from standardized testing performed by the laboratory professor, to ensure accurate and consistent results. Schmidt hammer test report of samundratar bridge nuwakot, bagmati.
The underlying principle of the rebound hammer test is. The hm75 schmidt concrete rebound test hammer provides rapid nondestructive estimates of inplace concrete strength and is a valuable tool when assessing the need for further testing. Aug 05, 2018 rebound hammer test is a nondestructive ndt test of concrete and simple concrete test which is used to test the compressive strength of concrete without any damage. Rebound hammer test rebound hammer test is done to find out the compressive strength of concrete by using rebound hammer as per is. After impact, the pressure is maintained on the instrument. The bridge is a 35m long span bridge which connects samundratar vdc 5 and 6. So the test have to be conducted by removing the carbonated layer and testing by rebound hammer over noncarbonated layer of concrete. Guidebook on nondestructive testing of concrete structures. The method is widely used for testing concretes manufacturers of such rebound hammers usually provide calibrated curves showing the. Compressive strength of concrete can be determined by testing of.
The swiss engineer ernst schmidt first developed a practicable rebound test hammer. Aij, architectural institute of japan, nondestructive test manual of methods for the. The rebound reading on the indicator scale has been calibrated by the manufacturer of the rebound hammer for horizontal impact, that is, on a vertical surface, to indicate the compression strength. To carry out this experiment, apparatus like rebound hammer is needed. Lab report gis and rs 2012ge56 16 if the concrete does not form part of a large mass any movement caused by the impact of the hammer will result in a reduction in the rebound number.
Pushing test hammer on end cover slowly, the hammer was unlocked and the button was bound out, stop pushing, removing the test hammer away from the surface, rebound pole was reach out, and at the same time the rebound hammer was hooked because of the pushing from compression spring, then it was ready for a test. Nowadays, the schmidt rebound hammer is still the surface hardness testing. Bureau of indian standard did not published any standard for this test upto 1991. Lab manual rebound hammer concrete strength of materials.
Nov 03, 2011 the rebound is read off along a graduated scale and designation as the rebound number of rebound index. Rebound hammer test schmidt hammer testing on concrete. For testing mass concrete for example, in roads, air field pavements and hydraulic structures. Report of rebound hammer test concrete applied and. Express the amount of water as a percentage by weight of the dry cement. In such cases the member has to be rigidly held or backed up by a heavy mass. The instrument firmly held perpendicular to the test surface and gradually pushed toward the test surface until the hammer impact. This rebound hammer test was conducted at three locations after 45 days. Pdf rebound hammer test method statement rusi sumdaram. When used in any other position, appropriate correction as given by the manufacturer is to be taken into account. All of the concrete rebound hammers we carry below accurately measure compressive strength of concrete, which directly determines the loadbearing capacity and durability of concrete structures.
The basic features of this equipment are shown in figure 1 below. Proceqs schmidt hammer portfolio is the most comprehensive available. Put the rebound hammer back together, and test it on the anvil again to get a calibrated reading. The shore scleroscope, ass mentioned before, measures the rebound hardness of a material, and depends on the resilience of the hammer for consistent results. Schmidt rebound hammer were made and used around the world 18.
The rebound hammer measurements results in figure 4. Pdf concrete has significantly influenced the nature of engineering projects. In the united states, the two most commonly used tests are the brinell and rockwell tests. Temperature of the rebound hammer itself may affect the rebound number. The rebound hammer strength test, being a nondestructive test, has its advantages of preserving integrity of sample. Rebound index natural sand plaster av rebound index loc.
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. The rebound hammer strength test, being a nondestructive test. Rebound hammer test on concrete principle, procedure. The rebound hammer test has been around since 1940s and today. Also, when in use, keep the hammer perpendicular to the surface you are testing with the scale pointing up, making it. This is undoubtedly the most commonly ndt test used to quickly assess the condition of a concrete structure.
1291 299 892 1451 1378 931 938 259 1298 1322 186 1101 1262 636 770 544 1148 1457 837 1410 1364 90 983 1005 1033 1283 135 1319 94 1408 70 100 18 297 63 1009 1456