Non-destructive monitoring of carbonation propagation in cementitious systems using the measurement of intrinsic electrical property

Monitoring carbonation in concrete is crucial for assessing the long-term durability of structures. Reducing clinker content by incorporating supplementary cementitious materials raises concerns about carbonation-induced corrosion and alterations in pore solution chemistry as well as microstructure. These changes can significantly impact the durability and engineering properties of concrete. Therefore, there is a critical need for thorough monitoring of carbonation propagation within the evaluation of the new generation of composite binders. To monitor carbonation, various techniques are employed. One common method involves splitting specimens and using pH indicators, such as phenolphthalein, to detect changes in the concrete's alkalinity. This paper presents the development of a novel carbonation monitoring method based on conductivity measurements in cementitious matrix. The proposed method leverages the correlation between carbonation and changes in concrete's electrical conductivity. The method enables in-situ monitoring of carbonation propagation in mortar specimens through application of embedded mini-sensors for measurement of electrical properties. The developed mini-sensors consist of 10 sets of 4-points-Winner electrodes (stainless steel) at a depth interval of 2.54 mm for conductivity measurements. By strategically placing these mini-sensors within the cementitious matrix, real-time measurements can be carried out, allowing for continuous monitoring of carbonation progression. This approach offers advantages in terms of cost-effectiveness, simplicity, and non-destructiveness compared to traditional destructive laborious methods.