Anvil is used as a certified reference Material to verify the Rebound Hammer calibration, Generally Rebound Hammer should give 80+/-2 on standard Anvil, having Rockwell Hardness HRC 66+/-2 as per IS 516 if the rebound hammer is functionally in good and calibrated condition.
Its primary purpose is to provide a standardized and consistent reference for checking and calibration of the accuracy of the rebound hammer (also known as Schmidt Hammer), which is widely used to assess the surface hardness and estimate the compressive strength of concrete structures.
Over time, the mechanical components of the rebound hammer, such as the spring, plunger, and the impact mass can undergo wear and tear, leading to deviations in the rebound readings. The steel anvil allows it to identify such errors, so that they are corrected before the hammer is used on the actual concrete surface.
The calibration anvil is constructed from high-grade alloy, hardened, and tempered to achieve surface uniformity and mechanical strength, ensuring that energy losses due to vibration or movement are minimized.
The impact surface of the anvil has a Rockwell hardness of approximately HRC 66 ± 2 as per IS 516, which provides a very dense surface similar to an idealized standard.
This ensures that when the rebound hammer’s plunger strikes the anvil, the resulting rebound number depends solely on the impact energy and hammer’s internal mechanism and not on surface inconsistency.
During the calibration process, the rebound hammer is held perpendicular to the anvil’s surface, and multiple test impacts, usually between 6 - 8 strokes performed.
The average rebound number is compared to the standard reference values, which should be generally 80 ± 2, and if the reading falls within this range, the hammer is considered properly calibrated.
However, if significant deviation is observed, it indicates that the hammer may need Repair, or mechanical servicing is required to restore its accuracy. Hence using a properly calibrated rebound hammer on Anvil guarantees that subsequent concrete test Rebound Hammer is accurate.
