rebound hammer test report

Apparatus consists of a spring controlled mass that slides on a plunger within a tubular housing. If the surface is very rigid ie high modulus the ball bearing would be.

Summary Of Result Of Schmidt Hammer Test On Columns At Dorcas Hall Download Table

74 shows a series of empirically determined curves relating the L-type Schmidt hammer rebound number at different.

. The testing anvil should be of steel having Brinell hardness of about 5000 Nmm2. All individual readings should be at least 25 mm 1 inch apart. It consists of a spring controlled mass that slides on a plunger within a tubular housing.

If the rebound numbers for concrete diameter and fixed rigidly within the being investigated are approximately the same or structure. The suppliermanufacturer of the rebound hammer should indicate the range of readings on the anvil suitable for different types. Various empirical correlations have been proposed for estimating the unconfined compressive strength of rocks from the Schmidt hammer rebound number.

Impact Energy for Rebound hammer for different Applications. Some of these standard procedures are. If estimating concrete strength takes at least two cores from six locations that have different rebound hammer number.

The Schmidt hammer rebound test has been briefly described in Chapter 3. The concrete surface to be tested must be smooth. It is necessary that the rebound hammer is checked against the testing anvil before commencement of a test to ensure reliable results.

The impact energy required for rebound hammers for different applications is given in table below. Index value obtained is rebound number R which is an indicator on the degree of hardness of rock surface being tested. Rebound hammer test Schmidt Hammer is used to provide a convenient and rapid indication of the compressive strength of concrete.

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 test result varies significantly with the age of the concrete. Rebound hammer test is frequently used in estimating the compressive strength of joint surface in rock.

Take 10 rebound hammer readings at each test area. Rebound hammer test lab report. This is achieved by pressing the plunger against the.

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. Higher than the concrete. 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.

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. How to do Concrete Hammer Test Work. Some of the disadvantages of the rebound hammer test can be listed as follows.

The results are corrected to a horizontal or vertical position using the correction curves provided by the manufacturer. Do not test over reinforcement with a cover of less than 20 mm 34 inch. 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.

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. Carry out rebound test on a calibrated Anvil supplied by. 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. Compressive strength rebound hammer test graph Application of rebound hammer test. 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.

It is used to test the fresh concrete as well as the in situ concrete after the final set. The rebound hammer often a Schmidt hammer measures the rebound of a weight from the back of an anvil pushed against the concrete surface. Not used to test frozen concrete.

The test is used to investigate the hardness of the concrete. 2733 Rebound hammer tests. 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.

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. Precision and Bias 101 PrecisionThe single-specimen single-operator ma-chine day standard deviation is 25 units 1s as deﬁned in Practice E 177. To find the exact location of poor quality and deteriorated concrete rebound hammer test is used.

The compressive strength can be read directly from the graph provided on the body of the hammer. The results are obtained based on a local point.

Case Study Of Strength Evaluation Of Structural Concrete Using Rebound Hammer Test Semantic Scholar