LAB MANUAL Rebound Hammer

LABORATORY

MATERIALS ENGINEERING ENGINEERIN G

LAB MANUAL- GROUP 8

Experimental title : Test of hardened concrete -Non destructive test Rebound hammer)

Objective: To find the quality of concrete in relation to standard requirement.

Introduction : The rebound hammer strength test , being a non-destructive test . has its advantages of preserving integrity of sample. Beside that, the test os relative simple , economical and versatile compared to conventional tests. This method widely used for testing concrete manufactures of such rebound hammer usually provide calibrated curve showing the relation of compressive strength and rebound number concrete only. But these hammer are conveniently be used to test stones and bricks also. This test have 3 sample of cube to be test. 16 time for vertical hammer position . End of this test, students be able to indentify the compressive strength based on the graph and find the quality of concrete in relation to standard requirement.

 Apparatus: 1) Rebound Rebound hammer 2) Abbrassive strength

Test specimens : 3 Concrete cube specimen (150x150x150mm)

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Procedure :

1.Firstly, the test area with smooth surface and no honey comb are selected. Then, using the abbrasive stone , grindly heavily textured or soft surface until there are smooth. 2.Then, draw the line of the specimen with 25mm each box 3.Then, hold the hammer firmly in a position that allows the plunger to impact perpendicularly to the surface being tested. 4.Gradually increase the pressure on the plunger until the hammer impacts. 5.Then, record the rebound number and also record the position and orientation of the hammer for each set of reading 6.The test result , take the average less than 6%. 7. Record the data of average rebound hammer, the compressive strength.

Result and calculation  :

1. Average of rebound hammer 2. Average of rebound hammer that neglected the +- 6units 3. Average the compressive strength

Discussion :

1. Dicuss what is rebound hammer test. Comment on your result. 2. Make the comment on quality of concrete based on average rebound number. 3. Discuss the limition or affect the quality of concrete on rebound hammer test 4. Discuss the precaution have you taken in your experiment in order to avoid the erroneous result.

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MATERIALS ENGINEERING

Figure 1 show the component of the hammer

Table 1 show the quality of concrete based on the average rebound number

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MATERIALS ENGINEERING

Figure 2 show the procedure of hammer