<![CDATA[This numerical study evaluates how moisture-induced variations in thermal diffusivity affect concrete delamination depth estimation using pulsed infrared thermography (PIRT). We employed a one-dimensional heat diffusion model, representing the delamination as a thermal barrier. We generated synthetic thermal responses for dry and saturated concrete with delamination depths ranging from 1 to 5 cm, using a 1 s sampling interval over a 4-h observation period. To represent measurement uncertainty, we added Gaussian noise with a standard deviation of 0.05 °C to each response, then smoothed the signals with a centered moving average using a 61-sample window. We evaluated the reliability of peak-time inversion through 200 Monte Carlo realizations under matched and mismatched conditions. The results show that increasing delamination depth reduces the thermal-contrast amplitude and increases the uncertainty in peak-time determination, with a more pronounced effect in saturated concrete because of its lower thermal-response amplitude. Under matched conditions, the estimation bias reached approximately 10.0% for dry concrete and 17.0% for saturated concrete, with maximum RMSE values of 1.10 and 1.35 cm, respectively. Under mismatched conditions, using the thermal diffusivity of dry concrete to invert the thermal response of saturated concrete produced a systematic shift of approximately −2.72% relative to the matched condition, consistent with the analytical prediction. For the parameters investigated, these results indicate that uncertainty in peak-time determination contributes more strongly to the overall estimation error than thermal-diffusivity mismatch. Nevertheless, using a thermal-diffusivity value representative of the actual moisture condition remains important for improving the reliability of PIRT-based delamination depth estimation in tropical coastal environments.]]>
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