MICROPILE QA/QC TESTING USING THERMAL PROFILING-Paper

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The paper describes adapting Thermal Integrity Profiling (TIP), typically used for drilled shafts, to assess hollow-bar micropiles on a coastal South Carolina retaining-wall repair project. Micropiles were selected because the site had limited access and occupied neighboring buildings that could be affected by vibration from other foundation methods.<br /><br />After installation, crews cleared grout from the hollow steel bar and filled its core with water. A single thermal-sensor wire was inserted, and temperatures were recorded for 24–36 hours as the grout hydrated. TIP software used the temperature data, grout volumes, and pile dimensions to estimate pile radius along its depth and create a three-dimensional profile. This provided information about diameter variations that routine inspection methods—such as checking grout volume and cutting-head size—cannot directly reveal.<br /><br />Testing was attempted on 12 piles; clearing the bar core was difficult on three. Results generally agreed with expected average pile diameters while also showing how diameter varied with depth. TIP may identify bulges, constrictions, or areas where cave-in or soil cuttings could limit grout cover and leave the steel bar vulnerable to corrosion. The authors note that interpretation depends on the bar remaining centered: a bar shifted toward one side could make temperatures suggest a false constriction.<br /><br />The authors conclude that TIP is a relatively practical supplement to full-time inspection and load testing, not a replacement for either. Because it is easier to apply across many piles, it may allow inspection of 10–20% of production piles, compared with the typical 1–2% tested by load testing. The results were not verified by excavating or extracting piles, so further testing is needed to compare TIP profiles with actual pile dimensions.

Keywords

Thermal Integrity Profiling

TIP

micropiles

hollow-bar micropiles

retaining wall repair

grout hydration

thermal sensor wire

pile diameter profile

coastal South Carolina

foundation inspection