Rebound hammer test - Types & characteristics
November 07, 2019
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⧪ Factors influencing the test results:
➤ Although rebound hammer saves effort, time and cost, it has serious limitations
The results are significantly influenced by :
(1) Mix characteristics like cement type, cement content
(2) The smoothness of the surface under test
(3) Types of coarse aggregate
(4) Size, shape, and rigidity of the specimen
(5) Age of concrete
(6) Moisture condition of the concrete
(7) Carbonation of concrete surface
(8) Type of mold
➤ IS: 13311 (Part-2)- 1992 clarifies the standard methodology for test and connection between solid block strength and bounce back number.
⧪ Strength evaluation
➤ The bounce-back sled test is directed to evaluate the overall strength of cement in light of the hardness at or close to its uncovered surface, It is alluring to complete.
➤ intermittent alignment bounce back hammer utilizing standard iron block on the off chance that new concrete.
➤ development, bounce back sled is aligned on solid test shapes for a given source
of constituent materials (viz. concrete. sand and totals), this alignment information can
a with sensible exactness in landing at identical in-situ solid shape strength of
Is new concrete (for example not over 3 months old cement).
➤ This alignment exercise might be done in a solid lab by throwing solid blocks of structured
➤ also, testing these solid shapes under the controlled condition with bounce back mallet too e test to devastation in the pressure testing machine. Alignment diagrams at that point can be drawn.
➤ This strategy may give profoundly mistaken outcomes for solid whose surface is
presented to the air for longer periods state over 3 months.
➤ This is expected to the solidifying of the solid surface because of carbonation, which may cause overestimation as much as half for the old structure.
➤ Thus, strength evaluation by Rebound hammer the test ought to be confined to generally new structures as it were.
➤ Overview of feeble and delaminating concrete For leading the bounce back mallet test, the solid surface ought to be level.
➤ This test is commonly not reasonable for use on spalled solid surfaces of upset structures.
➤ The bounce-back number demonstrates the close surface the hardness of the solid,
be that as it may, it tends to be utilized to recognize relative surface shortcoming in spread cement and can be utilized to decide the relative compressive strength of cement.
➤ Areas having a low bounce back numbers will be recognized as a frail surface e and such areas will be distinguished for further the examination, similar to erosion trouble, fire harm or unique development deformities of cement.
➤ This review ought to be completed at the framework that focuses on the network grid 300 mm x 300 mm.
➤ Table 1.14 gives rules for the subjective translation of bounce back hammer test
➤ results with reference to quality.
