Hammer Test

When testing the strength of concrete, the concrete test hammer uses a certain elastic force to transit the impact force of an impact hammer to the surface of concrete, IS: 13311 (part 2): 1992 specified, the rebound hammer method could be used for assessing the likely compressive strength of concrete with the help of suitable co-relations between rebound index and compressive strength. During the study, the distribution of rebound number for all the structural elements surveyed was tabulated. Then with the help of Equation 1 and Equation 2, Compressive Strength of Concrete (MPa) for the different elements were measured, where equation 2  is used for the slabs with correction and equation 1 is directly utilized for columns.

 

y=3.34Exp (0.0598RN)………………………………………………………………. (1)

y=3.34Exp {0.0598(RN-5)}……………………………………………………………. (2)

 

Testing concrete by test hammer has its own limitations. If all factors are taken into consideration the strength of concrete in a structure may be determined within an accuracy of +15%.