Determination of carbonation depth and pH in concrete containing crystalline waterproofing agents using the endoscopic method

Abstract

The monitoring of the carbonation process plays a key role in monitoring the health of reinforced concrete structures. In this study, the carbonation depth of concrete was measured using image processing and endoscopic methods, which relied on the pH level of the concrete containing crystalline waterproofing material. The results show that the carbonation depth and pH of the concrete were estimated by the nondestructive endoscopic method-based graphical user interface, with a high accuracy of 0.99. Furthermore, it was observed that crystalline waterproofing material increased the carbonation depth of concrete. Due to the lack of direct contact between the water molecules and the Na2O, the crystalline structure could not form sufficiently to prevent CO2 penetration. This phenomenon caused porosity in the mortar, a decrease in the velocity of the ultrasonic sound, and thus a loss of strength. However, a slight increase in compressive strength after carbonation was attributed to the sodium bicarbonate filling in the voids as a result of the reactions between Na2O, water molecules, and CO2.