Which hammer sizes should be used for Pile Integrity Testing (PIT)?

Generally, all piles should be tested with three different sized hammers. Heavier hammers provide better results for long piles. Lighter hammers provide better resolution, particularly near the pile top. If the piles have diameters greater than 1 m (36 inches), the recommended hammer masses are 1.5 kg, 3.5 kg, and 6 kg (3 lbs., 8 lbs., and 14 lbs.). The recommended hammer masses for smaller size piles are 0.5 kg, 1.5 kg, and 3.5 kg (1 lb., 3 lbs. and 8 lbs.).