A thermodynamic perspective on reinforcement corrosion in concretes produced with low-clinker blended binders

Concrete produced with blended binders with low clinker content, while having a reduced carbon footprint, pose additional challenges with respect to reinforcement corrosion. As the portland limestone cement is replacing ordinary portland cement, the utilization of conventional supplementary cementitious materials (SCM) has become the norm, and various types of alternative SCM are emerging, the focus has shifted toward the performance of concretes produced with low-clinker blended binders. While the synergetic reactions among clinker, limestone and SCM could provide significant benefits to concrete by reducing porosity, pore connectivity and transport coefficients, hence improving various mechanical and durability properties, they can also make reinforcing steel more vulnerable to corrosion. The corrosion-related factors that can be negatively affected in low-clinker systems comprise the chemistry of the pore solution including its pH, alkali content, and electrical resistivity; hydrated phase composition, including C-(A)-S-H content and types and calcium hydroxide content; pH buffer capacity; chemical and physical binding of alkalis and chloride. In this presentation, thermodynamic calculations are used to provide details on these challenges.