7.18 : 混凝土强度无损检测

Non-destructive tests, such as the rebound hammer test and penetration resistance test, can be used to determine the strength of concrete in an existing structure.

The rebound hammer, also known as the Schmidt hammer, houses a spring-loaded mass.

The hammer is held perpendicular to an even concrete surface by pressing the plunger against it, causing the spring to extend, retracting the mass.

When released, the mass rebounds from the plunger. The extent of this rebound is then measured on a scale fixed to the hammer and is called the rebound number.

The higher the value of the rebound number, the harder the concrete surface, indicating high concrete strength.

The penetration resistance test, also known as the Windsor Probe test, uses a gunlike device equipped with a triangular template with three holes.

The template is placed on the concrete surface, and probes are shot into the concrete through each of the three holes using the device.

The average of each probe's penetration through the hole is measured; the lower the penetration of the probe, the higher the strength of the concrete.