Comparison of nondestructive test methods for concrete. The quality of entire concrete of a structure cannot be fully assessed by testing a few concrete cubes. 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. Correlation between schmidt hammer and destructive. Schmidt hammer test or rebound hammer test of concrete. When the plunger of rebound hammer is pressed against the surface of the concrete, the. The rebound number is an arbitrary measure because it depends on the energy stored in the given spring and on the size of the mass. Schmidt hammer test is the most commonly used one in practice. Inspite of its popularity, this testing has not been standardized in any.
Small air pockets near the surface being tested result in low rebound values, while tests made over a hard aggregate will result in a high rebound value. Concrete as a composite materials, is generally composed of cement. Rebound hammer test is a nondestructive ndt test of concrete and simple concrete test which is used to. 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 reduce the need for concrete coring. Rebound hammer test procedure for concrete hardness. The rebound hammer strength test, being a nondestructive test, has its advantages of preserving integrity of sample. This digital concrete test hammer, microprocessor operated, entirely designed and manufactured by matest with advanced technology, performs basic concrete testing with continuous automatic recording of all parameters in accordance with en 125042 specifications, register and process data and then transfer them to a pc the unit consists of the standard mechanical model c380. Reliability of nondestructive tests for hardened 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. Concrete testing with the original schmidt hammer is the most frequently used method worldwide for nondestructive testing of concrete and structural components. Is schmidt hammer test a standard test for testing concrete. Product details the wm250 manual test hammer is the traditional instrument used for the nondestructive testing of hardened concrete. This concrete test hammer, entirely produced by matest, has aluminium frame and thanks to its very accurate manufacture processing and selected components ensures high precision test. Guidebook on nondestructive testing of concrete structures.
Comparison of nondestructive and destructive testing on. The standard rebound hammer provides a simple, easy and inexpensive method to estimate concrete strength properties. Digital concrete test hammer material testing equipment. Testing concrete by test hammer has its own limitations. The rebound of an elastic mass depends on the hardness of the surface against which its mass strikes. Pdf application of rebound hammer method for estimating. The hammer measures the rebound of a springloaded mass impacting. Provides both analog and digital readings rvalue strength determinations. Nondestructive testing of concrete by rebound hammer. The rebound hammer test and the ultrasonic device are used in the field of. The suitable methods for checking the calibration of the rebound hammer is to test the concrete cube of size 150mm 150mm 150mm with the help of rebound hammer and then with the compression testing machine ctm. Hammer test as a means of estimating the compressive strength of concrete is investigated by testing three groups of concrete cube specimens. Some hammer models produce a printout of test results. The compressive strength is measured by breaking cylindrical concrete specimens in a compression testing machine.
Proper use of the rebound hammer updated to reflect the. Rebound hammer test on concrete we civil engineers. Nondestructive testing of concrete methods of test. Also, when in use, keep the hammer perpendicular to the surface you are testing with the scale pointing up, making it. The concrete test hammer measures strength according to the schmidt principle. It is only a test used for estimating the strength of concrete in structure and it can hardly be considered as a substitute for compressive strength test. In 1948, a swiss engineer, ernst schmidt developed a test hammer for measuring the hardness of concrete by the rebound principle. This easytouse instrument provides a quick and simple test for obtaining an immediate indication of concrete strength in various parts of a structure. Suitable for finished concrete structures and buildings having strength resistances from 10 to 70 nsq. Schmidtrebound hammer test, used to evaluate the surface hardness of concrete.
A handy nondestructive testing instrument should be cheap, easy to operate and should have reproducibility for, fairly accurate results. Review of the rebound hammer method estimating concrete. Concrete test hammer material testing equipment matest. These factors need to be considered in interpreting rebound numbers. Compressive strength of concrete can be determined by testing of. For testing normal weight 225 concrete for lightweight concrete or 075 small and impact sensitive parts of concrete for testing mass concrete, 3000 for example in roads, air fields pavements and hydrau lic structures 5 cmjxking of apparatus ii. Cylindrical specimens are tested in accordance with astm c 39, standard test method for compressive strength of cylindrical concrete specimens. The compressive strength is measured by breaking cylindrical concrete specimens in a compressiontesting machine. 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 pitch of delaminated areas is differentfromsound infrared thermography ir optical camera.
Introdocton compressive strength of concrete is the most import ant input data for engineering calculations during the design of reinforced concrete structures. Concrete test hammer, concrete testing equipment, controls. The concrete test hammer is an excellent tool in the hands of experts. Rebound hammer test on concrete principle, procedure. This reasonablypriced alternative is made in america and meets the same published specifications as the original schmidt hammer. The operation of the hammer is very simple, yet it is not so simple as to entrust this. It has been used worldwide as an index test for a testing equipment to estimate strength of concrete due to its rapidity and easiness in execution, simplicity, portability, low cost and nondestructiveness. An astm designation number identifies a unique version of an astm standard.
According to this measurement method, the quality of concrete can be measured with the concrete test hammer. It is necessary to calibrate the rebound hammer before carrying out the test on hardened concrete. Also, when in use, keep the hammer perpendicular to the surface you are testing with the scale pointing up, making it easier to read. The concrete test hammer is also suitable for measuring hardness of rolled. Concrete rebount test hammers provide a rebound number, or r value, of hardened concrete. The impact of the test hammer would be affected by the elastic deformation of concrete sections less than 4 inches thick. The original schmidt os8000 is the original concrete test hammer, now digitally redefined and it is also the most advanced rvalue hammer ever made, with unmatched performance, ease of use, and versatility, as well as reporting on the go thanks to its mobile app. Concrete has significantly influenced the nature of engineering projects. As we already discussed the compressive strength of concrete by concrete cube test which is a destructive test worked out in the lab. In fact, there is about a variation of 1520% in concrete strength measured by the method. Always hold the concrete rebound hammer in both hands while in use.
These versatile concrete testing tools, also called swiss hammers or rebound hammers. For estimating the inplace concrete strength, astm c 31 provides procedures forfieldcuredspecimens. Active standard astm c805 c805m developed by subcommittee. Concrete test hammers testing instruments for a measurable. Schmidt hammer is in not a standard test for acceptance testing of concrete strength.
When the plunger of rebound hammer is pressed against the surface of the concrete, the spring controlled mass rebounds and the extent of such rebound depends upon the surface hardness of concrete. 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. Samples are taken during production and required tests are then carried out on the samples. Concrete strength test rebound hammer original schmidt live. It was invented by ernst schmidt, a swiss engineer.
It also provides a means of assessing strength development with curing. Aug 24, 2016 some hammer models produce a printout of test results. The work will present a detailed comparison between the destructive tests and nondestructive methods. Based on these syllabi, training course notes have been produced to cover industrial. The experimental studies using ultrasonic pulse velocity and schmidt rebound hammer as nondestructive tests ndt were presented in this paper to establish a correlation between the compressive strengths of compression tests and ndt values. The top quality test hammer available on the market. Testing concrete in structures nondestructive testing determination of rebound number. 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. Each hammer is designed for specific test applications. For testing normal weight 225 concrete for lightweight concrete or 075 small and impact sensitive parts of concrete for testing mass concrete, 3000 for example in roads, air fields pavements and hydrau lic structures 5 cmjxking of apparatus ii assessing the uniformity of concrete. The user must exercise professional judgement when testing carbonated concrete. These need to be fully understood before the test program starts, so that the correct test is used for the correct application. Before the hammer can be used for testing, the piston must be released out of the hammer into the testing position.
Concrete slump testing is used to evaluate the flow characteristics of freshly mixed concrete. Pdf non destructive testing of concrete by rebound. Testing of the concrete specimen plays and important role to know about the strength, durability and condition of the structure. Developed in 1948 by a swiss engineer named ernst schmidt, the device measures the hardness of concrete surfaces. Carbonation depth measurement test, used to determine whether moisture. Concrete rebound hammer construction materials testing. When the plunger of the rebound hammer is pressed against the surface of the concrete. Testing the strength of concrete without destructing or breaking it after hardening is a complex task. To conduct a slump test, concrete is placed into an inverted cone in three stages, using a metal rod to tamp down the concrete after every stage. Is schmidt hammer test a standard test for testing. Concrete is the oldest and most important construction material in the world. To assess the likely compresive strength of concrete by using rebound hammer as per is. Astm c805 c805m 18 standard test method for rebound. By referring to the some conversion tables, the rebound result of the test can be used to determine the.
All concrete test hammers measure the surface hardness of the material they are testing. Guide to testing and monitoring the durability of concrete structures. 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. The schmidt hammer test involves hitting the insitu concrete with a springdriven pin at a defined energy, and then the rebound is measured. The concrete test hammer concrete construction magazine. 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.
The rebound depends on the surface hardness of the concrete and is measured by test equipment. Can be supplied complete with traceable certificate of calibration. Besides, the test is relative simple, economical and versatile compared to. The test is essentially nondestructive, since concrete and structural members can be tested in situ, with only minor patching of holes on exposed faces. 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. The hm71 gilson concrete test hammer quickly provides reliable estimates of inplace concrete strengths, allowing rapid assessments of large areas and delineation of potential problem areas. Pdf this study examines the factors affecting the results of nondestructive testing of highstrength concrete performed on cubes and on. The concrete test hammer is a measuring tool for testing the strength of concrete. The rebound schmidt hammer is one of the oldest and best known methods of comparing the concrete in various parts of a structure and indirectly assessing concrete strength. Concrete test hammers are ideal for fast and economical nondestructive testing ndt assessment of inplace concrete strength consistency. Pdf non destructive testing of concrete by rebound hammer. Less coring, with concrete strength and uniformity evaluation using rebound hammer technology. Use type n rebound hammers that are commercially available to accommodate testing of various sizes and types of concrete construction.
The concrete hammer is supplied complete with plastic carrying case, grinding stone and instruction manual. Pdf rebound hammer test method statement rusi sumdaram. 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. Testing the compressive strength of a concrete cube using schmidt hammer. Impact energy for rebound hammer for different applications. By concrete construction staff download the pdf version of this article.
Schmidt hammer, type l nmm 2 designed for testing thinwalled structural components with a thickness of less than 4 100mm or rock cores. Used for the periodical calibration of the concrete test hammer 58c0181c and 58c0181dgt. The rebound hammer is a surface hardness tester for which an empirical correlation has been. Rebound hammer test, schmidt hammer test, nondestructive. Compressive strength testing 4400 the main reason to carry out ultrasonic pulse velocity test, rebound hammer test and compression test at the same concrete cube was to create a correlation between the compressive. Inplace strength of concrete a comparison of two test systems, and appendix to series 193, national ready mixed concrete assn. Schmidt rebound hammers for concrete strength and rock testing. The hammer is forced against the surface of the concrete by the spring and the distance of rebound is measured on a scale. Standard test method for rebound number of hardened. A test result is the average of at least two standardcured. Non destructive testing of concrete structures rebound. The rebound hammer test and the ultrasonic device are used in the field of nondestructive tests to determine respectively.
951 1118 1607 1595 352 95 694 393 1172 934 313 734 816 1070 578 828 1457 1013 1351 1356 1507 911 1478 319 772 1470 1103 893 1318 1369 1015 645 1036 763 622 1372 180 371 1141 1037 1317 190 37