Cost and Technical Comparison of Non-Destructive Test Methods for Drilled Shafts-Paper

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The paper compares Cross-Hole Sonic Logging (CSL) and Thermal Integrity Profiling (TIP) on seven 5-ft-diameter drilled shafts constructed for a transit-rail project. CSL measures ultrasonic signal travel between access tubes, while TIP uses embedded thermal wires to track concrete hydration temperatures and estimate shaft dimensions and concrete quality.<br /><br />TIP required less installation material and labor: project costs were $17,575, compared with $31,029 for CSL—a 43% reduction. Data collection, analysis, and reporting cost $4,260 for TIP versus $12,845 for CSL. Including both categories, total costs were $21,835 for TIP and $43,874 for CSL. TIP results were available about 24 hours after placement, roughly six days earlier than CSL results.<br /><br />The methods identified overlapping but not identical concerns. Both detected poor-quality concrete near the base of Shaft 2, which coring confirmed; the concrete was subsequently remediated. TIP initially indicated an anomaly in Shaft 3, but this was attributed to an incorrect recorded concrete volume. An early CSL test on Shaft 6 produced misleading anomaly indications because the concrete had not gained sufficient strength.<br /><br />The authors conclude that TIP can be a more economical and faster alternative for integrity assessment, but the methods can complement one another. CSL can help investigate questionable findings and verify successful post-grouting—an advantage TIP alone may not provide.

Keywords

Cross-Hole Sonic Logging

Thermal Integrity Profiling

drilled shafts

concrete integrity

transit-rail project

cost comparison

ultrasonic signal

thermal wires

shaft quality assessment

construction testing