rebound hammer test report

For Rebound hammer Nm 1 For Testing Normal Weight Concrete 225 2 For light-weight concrete or small and impact sensitive parts of concrete 075 3 For testing mass concrete for example in roads air field pavements and hydraulic structures 225 Table 1. Clean the surface of concrete ensure the concrete is clean and dirt free.

Rebound Hammer Test On Concrete Principle Procedure Advantages Disadvantages

The rebound hammer often a Schmidt hammer measures the rebound of a weight from the back of an anvil pushed against the concrete surface.

. 2733 Rebound hammer tests. The value of R can be used to estimate the compressive strength of rock using the following equation Franklin 1989. The method may be compared to dropping a large ball-bearing onto a concrete surface.

Impact Energy for Rebound hammer for different Applications. The test is used to investigate the hardness of the concrete. There are following advantages of rebound hammer test.

It is necessary that the rebound hammer is checked against the testing anvil before commencement of a test to ensure reliable results. Apparatus consists of a spring controlled mass that slides on a plunger within a tubular housing. In rebound hammer test a spring loaded mass has a fixed amount of energy imparted to it by extending the spring to a fixed position.

The impact energy required for rebound hammers for different applications is given in table below. Procedure for Schmidt hammer test or Rebound Hammer Test. To this aim one of the most widely spread techniques is the rebound hammer Schmidt hammer test for which calibration is still related to the original Schmidt curve dating back to the early.

To find the exact location of poor quality and deteriorated concrete rebound hammer test is used. 9142 Orientation of hammer during test 915 Average rebound number for test area and 9151 Remarks regarding discarded readings of test data or any unusual conditions. To do this the Schmidt hammer is tested against the Steel test anvil which has a Brinell hardness number of about 5000MPa.

This 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. Precision and Bias 101 PrecisionThe single-specimen single-operator ma-chine day standard deviation is 25 units 1s as deﬁned in Practice E 177. Before starting the procedure calibration of the hammer is required.

It is used to test the fresh concrete as well as the in situ concrete after the final set. 3 It is the most accurate method for. 2 The result is highly sensitive to any change in the elastic properties of the material.

How to do Concrete Hammer Test Work. Carry out rebound test on a calibrated Anvil supplied by. This is achieved by pressing the plunger against the.

1 It is used for determination of modulus of elasticity ie Youngs Modulus which shows material toughness and strength eg metals more than timber. Rebound hammer test is frequently used in estimating the compressive strength of joint surface in rock. For tests conducted in situ on a rock mass the rebound hammer can be used at any desired orientation provided the plunger strikes perpendicular to the surface tested.

Some of the disadvantages of the rebound hammer test can be listed as follows. The compressive strength can be read directly from the graph provided on the body of the hammer. Rebound hammer test Schmidt Hammer is used to provide a convenient and rapid indication of the compressive strength of concrete.

The test specimens should be as large a mass as possible in order to minimise the size effect on the test result of a full-scale structure. Compressive strength rebound hammer test graph Application of rebound hammer test. ASTM C805 Standard Test Method for Rebound Number of Hardened Concrete summarizes the procedure as A steel hammer impacts with a predetermined am ount of energy a steel plunger in.

The testing anvil should be of steel having Brinell hardness of about 5000 Nmm2. The suppliermanufacturer of the rebound hammer should indicate the range of readings on the anvil suitable for different types. Rebound hammer test lab report.

The concrete surface to be tested must be smooth. Index value obtained is rebound number R which is an indicator on the degree of hardness of rock surface being tested. If the surface is very rigid ie high modulus the ball bearing would be.

The test result varies significantly with the age of the concrete. The results are obtained based on a local point. 150 mm cube specimens are preferred for calibrating rebound hammers of lower impact energy 22 Nm whereas for rebound hammers of higher impact energy for example 30 Nm the test cubes should not be.

It consists of a spring controlled mass that slides on a plunger within a tubular housing. The issue of concrete strength often arises in civil engineering practice either due to quality control of new constructions or due to the assessment of existing structures. The results are corrected to a horizontal or vertical position using the correction curves provided by the manufacturer.

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