Does aci recommend any other nondestructive testing ndt method for inplace strength evaluation. The rebound hammer test is codified in astm c805 3 and csn en 125042 4. Case study of strength evaluation of structural concrete. 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. This article is to discuss the rebound hammer and how to successfully use it to evaluate concrete. Betonprufhammer bedienungsanleitung sclerometre a beton nnr. Rebound hammer test rebound hammer test is done to find out the compressive strength of concrete by using rebound hammer as per is. Principles of the rebound hammer ernst schmidt, a swiss engineer, developed the modern rebound hammer in 1948. Astm c805, standard test method for rebound number of hardened concrete, summarizes the procedure as a steel hammer impacts, with a predetermined. Typically, a rebound hammer will result in a rebound number of 80 2 when tested on the anvil described in section 4.
In addition, influence of test conditions and some general guidance on the interpretation of. Bureau of indian standard did not published any standard for this test upto 1991. 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. Pdf the schmidt hammer in rock material characterization. The number of test impacts required for a valid rebound number is defined in the standards. Standard test method for rebound number of hardened. Also, when in use, keep the hammer perpendicular to the surface you are testing with the scale pointing up, making it easier to read. Before starting the procedure calibration of the hammer is required. The method is widely used for testing concretes manufacturers of such rebound hammers usually provide calibrated curves showing the relation of compressive strength and. Also structures which are suspected to any strength failure are.
Schmidt hammer test or rebound hammer test of concrete. Schmidt hammer test, hammer rebound, ultra sonic test, pulse velocity, core samples, compression strength, combined method, statistical analysis. Rebound hammer is a very simple apparatus to work with. If the situation demands,the rebound hammer can be. Oct 29, 2016 the rebound hammer is also one of the easiest pieces of equipment to misuse. The rebound hammer has been around since the late 1940s and today is a commonly. Reliability of rebound hammer test in concrete compressive. Dirt or other loose material on the surface can be removed using a. The individual impact points must be spaced at least 25 mm apart. Destructive tests can provide direct information, but are relatively expensive, time. Central to the improvement of the concrete infrastructure are tools that evaluate the condition of existing construction. Aug 05, 2018 procedure for schmidt hammer test or rebound hammer test. The rebound hammer strength test, being a nondestructive test, has its advantages of preserving integrity of sample. Application of rebound hammer method for estimating.
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. Push the concrete test hammer against the test surface at moderate speed until the impact is triggered. 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. The rebound hammer test is one of the nondestructive tests used to check. For taking a measurement, the rebound hammer should be held at right angles to them surface of the concrete member. Rebound hammer test is a nondestructive testing method of concrete which provide a convenient and rapid indication of the compressive strength of the concrete. Procedure for schmidt hammer test or rebound hammer test. Schmidt hammer rebound number is higher as density or unit weight increases. Standard test method for rebound number of hardened concrete1. 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. The rebound distance is measured on an arbitrary scale marked from 10 to 100. The test anvil needs to be supported on a rigid base to obtain reliable rebound numbers. Hammer type, test range and calibration the earlier isrm suggested method 1 endorsed the use of. Figure 1 presents an example of a school built with re in france.
Rebound hammer rebound hammer a handy nondestructive testing instrument should be cheap, easy to operate and should have reproducibility for, fairly accurate results. Before the hammer can be used for testing, the piston must be released out of. Proper use of the rebound hammer updated to reflect the. Statistical case study on schmidt hammer, ultrasonic and core. Part 2 rebound hammer 1 scope this standard covers the object, principle, apparatus and procedure of rebound hammer test method. The rebound hammer is also one of the easiest pieces of equipment to misuse. Laboratory manual imam abdulrahman bin faisal university. Rebound hammer against the concrete surface to be tested.
Test procedure the reading is very sensitive due to local variation in the concrete, especially to aggregate particles near to the surface. Then the compressive strength was ascertained on a pressure testing machine. However, no specific ndt methods or equipment for inplace strength evaluation are listed. To perform a test, make sure the piston is extended and gently press the. We use this test to differentiate the questionable and acceptable parts of the structure or base on its strength comparison between two different structures. Review of the rebound hammer method estimating concrete. This standard covers the object, principle, apparatus and procedure of rebound hammer test method for determination of a rebound number of hardened concrete using a springdriven steel hammer. It is one of the most useful non destructive techniques in evaluation of concrete structures.
Around each point of observation, six readings of rebound indices are taken and average of these. Proceqs schmidt hammer portfolio is the most comprehensive available. Rebound hammer test procedure for concrete hardness. Developed in 1948 by a swiss engineer named ernst schmidt, the device measures the hardness of concrete surfaces. Keep adjusting and testing the rebound hammer until it. The reason for such a success is not the reliability of. Standard test method for rebound number of hardened concrete1 this standard is issued under the. 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. Rebound hammer test schmidt hammer testing on concrete. Procedure to determine strength of hardened concrete by rebound hammer. Rebound hammer test 10 types of factors which effect it. When the plunger of rebound hammer is pressed against the surface of the concrete, the. Guidebook on nondestructive testing of concrete structures.
Besides, the test is relative simple, economical and versatile compared to. Assessing the rebound hammer test for rammed earth. Isrm suggested method isrm suggested method for determination of the schmidt hammer rebound hardness. Calibration and reliability of the rebound schmidt hammer test. A great number of research works have been conducted in e hammer test is a reliab le tool for estimating concrete compressive strength. If the readings fall outside of this range, take the rebound hammer apart and try to adjust it again.
Constructed structures have to be investigated for evaluating the serviceability and safety from time to time. This device is universally used because of a hardened steel hammerimpacted on the concrete by a spring. Standard test method for rebound number of hardened concrete. Put the rebound hammer back together, and test it on the anvil again to get a calibrated reading.
Yasar and erdogan 2004a derived the following empirical correlation between them based on the test results of six different rock types. The procedure is repeated until the wall is completed. James instruments specalises in nondestructive testing equipment for concrete and other construction materials. Using the humboldt concrete rebound hammer always hold the concrete rebound hammer in both hands while in use. Rebound hammer test is the most appropriate and useful testing methods for comparing the relatively weaker and stronger areas of concrete. 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. Gupta, niharika gupta and amandeep singh one of the most widely spread techniques to estimate the compressive strength of concrete is the rebound hammer test, also known as schmidt hammer test. Besides, the test is relative simple, economical and versatile compared to conventional crushing tests.
In the three decades since the earlier isrm suggested method for conducting the sh test was published 1, researchers have sought to establish correlations between the sh rebound values r and the ucs and e for different rock types. Astm c805 c805m 18 standard test method for rebound. 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. Rating is available when the video has been rented. Rebound hammer test on concrete principle, procedure. Nondestructive testing of concrete methods of test.
Note in view of the limitations of each method of nondestructive testing of concrete, it is essential. The test can thus be conducted horizontally on vertical surfaces or vertically upwards or downwards on horizontal surfaces. Destructive and nondestructive testing ndt techniques are applied. 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 values r of the sample cubes were measured using the concrete test hammer. Rebound hammer test is conducted around all the points of observation on all accessible faces of the structural element. Procedure the method of using the hammer is explained using. Isrm suggested method isrm suggested method for determination. Nondestructive testing of concrete by rebound hammer. Dirt or other loose material on the surface can be removed using a grinding stone prior to the test. In addition, influence of test conditions and some general guidance on the interpretation of test results are also given. Clean the surface of concrete, ensure the concrete is clean and dirt free. Estimating the strength of concrete using surface rebound. Rebound hammer test relates one concrete element with other concrete elements in terms of quality. It was invented by ernst schmidt, a swiss engineer. In 1948, a swiss engineer, ernst schmidt developed a test hammer for measuring the hardness of concrete by the rebound principle. To do this, the schmidt hammer is tested against the steel test anvil which has a brinell hardness number of about 5000mpa. C805 c805m18 standard test method for rebound number of hardened concrete rebound number insulating boards springdriven steel hammers.
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. Concrete inspection rebound hammer elcometer 181 analogue concrete test hammer standards. Ceyhan limestone, barbaros marble, antique cream limestone, osmaniye marble, toprakkale basalts, and handere sandstone. In each test, at least 10 test hammer impacts were performed on one. We use the rebound hammer to get an indication of the concrete.
The rebound hammer should be considered as a means of determining variations of strength within a structure rather than an accurate means of assessing strength. The surface of hardened concrete is struck with the hammer, and concrete compressive strength is estimated via the surface hardness rebound value. The rebound distance is recorded as a rebound number corresponding to the position of the rider on the scale. The schmidt hammer provides a quick and inexpensive measure of surface hardness that is widely used for estimating the mechanical properties of rock material. The rebound hammer test is one of the nondestructive tests used to check the compressive strength of concrete. The functionality of the rebound hammer shall have been verified in accordance with 6. Pdf the rebound hammer strength test, being a nondestructive test, has its advantages of.
Pdf rebound hammer test method statement rusi sumdaram. Preparing test surface inspectors should pay attention to the following considerations prior to conducting a rebound hammer test. 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. Apr 16, 2019 rebound hammer test relates one concrete element with other concrete elements in terms of quality. Acceptability of rebound hammer test is evaluated by different research works and studies. For taking a measurement, the rebound hammer should be held at right angles to the surface of the concrete member. A number in parentheses indicates the year of last reapproval. Concrete surfaces are thoroughly cleaned before taking any measurement. Pdf application of rebound hammer method for estimating. An empirical relationship has been determined between the a absorbed by the concrete when given a high impact and its compressive. Statistical case study on schmidt hammer, ultrasonic and. 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. Objective determine compressive strength of concrete by using rebound schmidt hammer.
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