Do you consider using TIP to test the bored piles for your project? Please see what Ishimwe and Coleman (both from GRL*) can tell you about their experience with drilled shafts constructed for the Jane Byrne interchange in Chicago:
Phase I of the project was tested with cross-hole ultrasonic (CSL) equipment that detected flaws in 54% (more than one-half) of the tested drilled shafts - a real headache for the contractors.
Following the contractor’s request, Phase II shafts on the same site were tested only by the TIP thermal method. Surprise: All drilled shafts tested were declared acceptable!
What happened? Has the contractors’ workmanship improved significantly between Phase I and II? It’s inconceivable, so what else has changed? Clearly, the switch from the established CSL method to the TIP did the trick for the contractors and eliminated all flaws.
* GRL is the sister company of PDI, the inventor, and manufacturer of the TIP system ** The picture below shows a Thermal profile vs. the CSL profile of the same pile. Not related to the mentioned above.