Evaluating Thermal Integrity Profiling Defects and Rating Criteria

Thermal Integrity Profiling is a non-destructive test method used on cast-in-place concrete deep foundation elements such as drilled shafts. The method has progress steadily over the last 15 years with improvements to the equipment, data acquisition and analysis of the data. Current analysis of TIP data incorporates temperature vs depth and temperature vs. time. The current acceptance criteria for TIP includes using reductions in effective shaft radius and concrete cover (Piscsalko, et al. 2016). However, these criteria are heavily based on knowledge of concrete volume and can be significantly affected by the lack of good concrete volume data. An additional criterion using temperature is proposed for potential use in the industry, which can supplement the existing effective radius/cover criteria and will be less dependent on volume knowledge. However, the relationship between temperature reductions and defect size and position are not well known for various reasons. The major reasons for this include; not a lot of studies/data available, variations in mix designs, variations in shaft sizes, and variation in defect types. Research was recently performed by the Authors on three drilled shafts with manufactured defects under grants from DFI and ADSC. The study included running theoretical simulations to predict the sensitivity of temperature reductions to the defect size and location. Data was collected and the temperature with depth was compiled for various defects. The results show a promising relationship between temperature reduction and defect cross sectional area. When considering local temperatures and average temperature changes, the criteria can consider location and size. When including data from other recent research studies for similar size shafts and defects, we found the relationship to be consistent with our data. The findings of this research provided a better understanding of the relationship between temperature reductions and defect size and location and provide the basis of the proposed temperature criteria.