Connecting the Influence of Nano-TiO ₂ on the Characteristics of Pore Systems with the Frost Resistance of Concretes with and without Supplementary Cementitious Materials

Nano-TiO ₂ has been reported to be effective in improving the frost resistance of concretes; however, its effectiveness varies depending on the type of the binder system, particularly in mixtures containing supplementary cementitious materials (SCMs). This study investigates the influence of nano-TiO ₂ on the pore system characteristics and frost resistance of concretes made with and without SCMs, specifically Class C fly ash (FA) and Grade 100 slag cement. Both scaling resistance and freeze-thaw performance were evaluated. Results indicate that the addition of nano-TiO ₂ significantly improves the frost resistance of FA concrete compared with mixtures containing only ordinary Portland cement or slag cement. A practical and user-friendly indicator for characterizing the pore system is proposed and used to establish a correlation between pore structure and frost resistance. The findings reveal a strong link between the beneficial effect of nano-TiO ₂ on the pore system and the improved durability of FA concrete, highlighting a synergistic interaction between nano-TiO ₂ and FA.