1. Appearance
The two instruments have a similar appearance, but they differ in length.
2. Nominal Energy
The impact force of a high-strength rebound hammer is greater than that of a standard rebound hammer.
- 225-type standard rebound hammer: Nominal energy is 2.207 J.
- 450-type high-strength rebound hammer: Nominal energy is 4.500 J.
- 550-type high-strength rebound hammer: Nominal energy is 5.500 J.
3. Calibration Values
The calibration values differ between the two types of rebound hammers:
- 225-type standard rebound hammer (on a normal steel anvil, Rockwell hardness HRC = 60±2): 80±2.
- 450-type high-strength rebound hammer (on a high-strength steel anvil, Rockwell hardness HRC = 60±2): 88±2.
- 550-type high-strength rebound hammer (on a high-strength steel anvil, Rockwell hardness HRC = 60±2): 83±1.
4. Measurement Range
The measurement ranges are different:
- Standard rebound hammer: Suitable for concrete with strengths of 10-60 MPa.
- High-strength rebound hammer: Suitable for concrete with strengths of 50-100 MPa.
Applications:
- High-strength rebound hammer: Used for testing large concrete components or high-strength concrete. It can also detect aggregate and transition layers.
- Standard rebound hammer: Used for testing general building components and bridges, such as slabs, beams, and columns, especially for on-site strength testing.
5. Impact Area
In high-strength concrete testing, the larger impact energy of the high-strength rebound hammer extends the impact area beyond the cement paste layer, reaching the aggregate and transition layer. As a result, increasing the impact energy does not increase the rebound value but may decrease it.
Summary:
High-strength rebound hammers are specialized tools for testing high-strength concrete and large structures, while standard rebound hammers are more suitable for general concrete testing in typical construction scenarios.
