The test hammer submit to standard of GB/T9138-1988 and JJG817-93 and JGJ/T23-2011 and ASTM C 805. HT-225 concrete test hammer is applied to test the compressive strength of building concrete components, bridge and so on. Parameter: Test range: 10~60Mpa Standard impact energy: 2.207J(0.225Kgf.m) Stroke of rebound hammer: 75mm Friction of pointer slider: 0.5N~0.8N Sphere radius of rebound pole SR: 25mm +/- 1mm Average rebound value on steel anvil Rm: 80±2 Size: 54*278mm Weight: 2KG