CARBONATION IN CEMENTITIOUS MATERIALS: CRACKS IN MESOPORES

Other conference contribution, 2024

Carbonation is a natural process in cementitious materials, where carbon dioxide from the environment diffuses into the pore solution and reacts with calcium ions to form calcium carbonate. While this carbonation process can be regarded as a degradation scenario due to its effect on the corrosion of reinforcement, it can also have a significant impact on the material's microstructure and pore size distribution. Although the microstructural changes induced by carbonation are often considered positive, there are increasing concerns about the potential generation of microcracks within the carbonated cement matrix. These microcracks can further alter the pore structure and compromise the mechanical properties of the material. Accurately detecting and characterizing these carbonation-induced microcracks is particularly challenging, as producing representative samples is difficult.

In this study, a multi-faceted approach was employed, utilizing pH indicators, micro-hardness testing, and electrical conductivity measurements on cement mortar samples subjected to accelerated carbonation. After one month of CO2 exposure, the pH indicator gave a carbonation depth of 6 mm. The microhardness data showed an increase in hardness in the carbonated zone meaning that carbonation causes densification of microstructure. Coupled with that, electrical conductivity measurements aligned with pH indicator results.  The study concludes that electrical conductivity and microhardness can be employed to investigate carbonation in cementitious systems.