STRENGTH-ESTIMATING EQUATION OF HIGH-STRENGTH CONCRETE USING REBOUND HAMMERS

An experimental study was conducted using 2 types of rebound hammers for high-strength concrete ranging 49 to 150 MPa as design strength. Based on rebound numbers and rebound speed ratios obtained by hitting concrete specimens, compressive strength in structure, that is core strength, was estimated. As a result, rebound numbers and rebound speed ratios were independent of loading stress to concrete and addition of polypropylene short fiber. Based on these results, strength-estimating equations of high-strength concrete were suggested using rebound numbers and rebound speed ratios. These equations have more than 85% precision of compressive strength in structure.