Speaker
Description
Carbonation in reinforced concrete (RC) is a physicochemical process that progressively reduce pore solution alkalinity and create conditions conducive to reinforcement depassivation and corrosion. Several non-destructive testing (NDT) methods, including ultrasonic and electrical techniques, have been investigated for carbonation detection. However, current practice primarily relies on invasive procedures, such as core extraction and phenolphthalein indicator testing. The use of infrared thermography (IRT) for carbonation assessment remains insufficiently investigated and lacks comprehensive validation. This study evaluates the feasibility of infrared thermography as a non-contact, non-destructive method for detecting carbonation in concrete. The working hypothesis is that carbonation alters the near-surface thermal properties of concrete, resulting in surface temperature contrasts (ΔT) detectable under controlled thermal excitation. These contrasts are expected to exceed the noise-equivalent temperature difference (NETD) of the infrared cameras and be statistically distinguishable from those in non-carbonated specimens. Concrete specimens with water/cement ratios of 0.45, 0.50, and 0.60 were cast and exposed to accelerated carbonation under controlled laboratory conditions for periods ranging from 14 to 35 days. The results were systematically compared with those obtained from non-carbonated reference specimens. Moreover, electrical resistivity testing was performed concurrently to provide complementary data on microstructural changes induced by carbonation. Phenolphthalein testing was used as the reference method for the validation of the results. The preliminary results indicate statistically significant differences in thermal response between carbonated and non-carbonated specimens under identical thermal loading. Complementary electrical resistivity measurements provide additional evidence of differences between carbonated and non-carbonated concrete.
