Rebound Hammer Procedure & Guidelines

Rebound Hammer Procedures

• Make surface smooth, if necessary, and dry.
• Use grids points over an area to avoid bias.
• Hold hammer normal to the surface.
• Take as many readings as possible.
• Convert readings to comp. strength (calibration).
• Note correction for inclined surfaces.

Also Read Ultrasonic Pulse Velocity Test

Rebound Hammer Guidelines

• Conduct on smooth and uniform face.
• Avoid rough spots, honey combs.
• Avoid troweled surfaces.
• Thin sections (< 100 mm)  should be backed up to avoid deflections.
• Take at-least 15 rebound readings in any one test.
• Calculate the mean.
• Compare deviation of readings from the mean.
• Test is considered reliable if the deviation of ten readings is not more than the following:

          Rebound value         15        30       45
          Deviation                  2.5        3         3.5

• Use  best 10 readings for calculating the mean.
• Determine compressive strength by referring to rebound number vs strength charts against the mean value.
• Best accuracy achievable is within + 20%