Concrete Test Hammers are ideal for fast and economical nondestructive testing (NDT) assessment of in-place concrete strength consistency. These versatile concrete testing tools, also called Swiss hammers, Schmidt hammers or rebound hammers, provide a rebound number, or R value, of hardened concrete. Rebound testing reveals areas of inconsistent quality, allows estimates of in-place compressive strength, isolates areas damaged by freezing or fire, and areas requiring more advanced NDT applications or coring.
View or download Concrete Test Hammer Comparison Chart to compare compressive strength and impact energy.
All models operate by pressing a plunger rod against a concrete surface until a spring-loaded mass is released, causing the plunger to impact on the concrete surface. On analog models, a sliding indicator shows rebound numbers. Advanced electronic versions use sensors and accelerometers for more repeatable R values. Relative strength curves are often provided with these units to estimate strength from the rebound number, but accuracy is greatly improved with the preferred method of user-produced laboratory correlations with compression test specimens of the same mix design, as described in ASTM C805 and ACI 228.1R.