Rebound Hammer Test: An Investigation into Its Reliability in Applications on Concrete Structures

Figure 9

Calibration curve for different concrete ages after casting (standard curing conditions). Calibration curve: R_c = e^aRI; RI = rebound index; a ∈ [0.12, 0.14]; R² ≅ [0.61, 0.81]. Inside any dataset, C.o.V. ≅ 13% for <100-day cubes; C.o.V. ≅ 22% for cubes∈[28, 100] days; C.o.V. ≅ 11% for 7-day cubes.