Scaling Risk Index of Concretes Containing Nano-TiO₂ and Supplementary Cementitious Materials

This paper presents a novel approach for assessment of scaling resistance of concretes with variable compositions (i.e., with and without addition of nano-TiO2 as well as with and without addition of fly ash and slag cement). The proposed approach is based on correlations between the data from thermogravimetric analysis of hydrated pastes and the results from actual scaling resistance tests. The results of the traditional (i.e., following the ASTM C672-03 method) scaling resistance test revealed that the effect of nano-TiO2 on the scaling resistance of concrete depended on the composition of the cementitious binder system (i.e., it was observed to change depending on whether the binder system contained or did not contain supplementary cementitious materials [SCMs]). While the use of nano-TiO2 improved the strength regardless of the type of concrete (i.e., it was effective in both plain concretes and in concretes with SCMs), the effect of nano-TiO2 addition on the scaling resistance was affected by the type of binder used in the mixture. The proposed scaling risk index correlated well with the actual scaling resistance test data (obtained from the ASCTM C672-03 test) from ordinary Portland cement and fly ash concretes with different mixture proportions and cured at different temperatures before the test.