Thermal Integrity Testing; New Scenarios and Methods.-Paper

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The paper examines how thermal integrity testing (TIT), which uses heat generated during cement hydration to identify anomalies in deep foundations, can be applied to newer construction scenarios and sensing methods. Case histories and numerical simulations are used to guide test design and interpretation.<br /><br />For low-carbon concrete containing high proportions of ground granulated blast-furnace slag (GGBS), heat develops more slowly and peak temperatures are lower. Monitoring may therefore need to continue longer, particularly for CEM IIIB mixes. Smaller-diameter piles produce less heat, reducing defect visibility; the authors report that CEM IIIB piles above about 0.9 m can generally be tested effectively, while smaller piles may have reduced sensitivity.<br /><br />For deep continuous flight auger (CFA) piles, sensors mounted on a central bar can provide full-length testing where conventional methods have limited reach or reinforcement cages are impractical. This approach can identify major defects, but results are less sensitive than measurements from a reinforcement cage. The bar must be kept central and rigid, since eccentricity or buckling may resemble a defect.<br /><br />Marine piles exposed to water can lose substantial heat, making anomalies harder to detect in exposed sections. Temperature measurements during concreting can provide additional information by revealing the passage of concrete and cooler inclusions or mixing with support fluid.<br /><br />The paper also assesses distributed temperature sensing using fibre-optic cables. Although its measurements average temperature over a defined spatial resolution, comparisons with simulations and conventional thermal wire show that it is suitable for TIT when the instrument’s resolution is properly specified.<br /><br />Overall, TIT remains useful across a wider range of foundations, but its sensitivity depends on concrete mix, pile size, exposure conditions, sensor position and measurement method. These factors should inform both test selection and interpretation.

Keywords

thermal integrity testing

deep foundations

cement hydration heat

GGBS concrete

CEM IIIB

continuous flight auger piles

fibre-optic sensing

temperature monitoring

pile defects

numerical simulations