Multi technique characterization of the carbonation affected zone including non-destructive single sided 1H NMR

Carbonation of cement-based building materials is not only a frequent trigger for corrosion of the reinforcement, but also causes various significant property changes in the carbonated layer. In addition to the decrease in the pH of the pore solution, carbonation is accompanied by a modification in the pore structure due to dissolution and precipitation reactions. The progress of carbonation is currently commonly measured by the phenolphthalein test. In this study, the non-destructive unilateral hydrogen nuclear magnetic resonance (1H NMR) was used to determine the carbonation progress of mortars as well as changes in the pore structure. The 1H NMR results were correlated and validated with known methods for characterizing the carbonation progress, including the carbonation depths, but also other structural and mineralogical changes. These results serve as a proof-of-concept which gives reason to apply this non-destructive method to further building materials, especially new environmentally-friendly binders.