Low Strain Pile integrity test or Pulse Echo Test
Pile integrity test is a non destructive integrity test method for foundation piles. The method evaluates continuity of the pile shaft and provides information on any potential defects due to honeycombs ,necking ,potential bulbs , sudden changes in soil stratum,concrete quality in terms of wave speed . It is known as low strain method since it requires the impact of only a small hand held hammer and the resultant strains are of extremely low magnitude . the test procedure is standardized as per ASTM D5882 and also forms part of various specifications and code provisions worldwide.
The testing is conducted by an experienced engineer after atleast 75% of the required compressive strength of concrete is achieved. The concrete at the pile top surface must be relatively smooth with sufficient space for attachment of the motion sensing device and hammer impact area.
The tesing involves attachment of an accelerometer onto the pile top with the help of boonding material like candle wax etc.after attachment, the pile is impacted with a hand held device , Typically six blows are impacted to the hammer and an average of similar of these blows constitutes one data set.