Assessing the Integrity of Deep Foundations Using Thermal Integrity Profiling (TIP)

Thermal integrity profiling (TIP) is a non-destructive, innovative technique used to evaluate the structural integrity of concrete foundations. The heat released by early-age concrete as it cures causes variations in local temperature due to abnormalities in the concrete shaft. Temperature sensors installed on the reinforcement cage collect detailed temperature data across the full concrete pile in order to accurately identify these temperature changes during concrete curing. Using the heat produced during the concrete or grout curing process, this testing technique evaluates the integrity of the deep foundation over the measured length. The tests were conducted on two bored concrete 1200 mm diameter instrumented bidirectional static load test piles (namely, PTP1 and PTP2) in Dubai, United Arab Emirates. For both test piles, a temperature drop was observed at the sacrificial jack assembly position, which was brought about by heat loss as a result of the assembly behaving as a heat sink. Thermal data show that the effective average radius is usually in line with the intended 1200 mm diameter up to the depths of around 22.0 m for PTP1 and 39.0 m for PTP2. The radius decreases by more than 6% below this depth to the design toe level of the piles, suggesting a temperature reduction that may be caused by the presence of slightly lower quality concrete. The results show that TIP was able to provide reliable and comprehensive temperature data in a cost-effective way for assessing the pile integrity.