Concrete Test Hammers are ideal for fast, inexpensive, nondestructive estimations of in-place strength of hardened concrete. Concrete rebound hammer tests can help determine where test cores should be taken and locate damage from freezing or fire. Useful range covers concrete strengths from approximately 1,400—8,000psi (10—55mPa).
The plunger rod is pressed against a concrete surface until a spring-loaded mass is released, causing an impact on the concrete. Rebound of the mass is registered on the hammer as the “rebound number.” Included calibration curves provide estimated strength from rebound number, but accuracy is greatly improved by user-produced laboratory correlations with compression test specimens of the same mix design, as described in ASTM C805.