Study on Freeze-Thaw Damage of Nano-Modified Concrete Under Complex Environmental Factors

In order to study the influence of nano-materials on durability and deterioration of concrete under complex environment, nano-modified concrete with different types (SiO2 and TiO2), different particle sizes (15 nm and 30 nm) and different dosage(0.2%, 0.4%, 0.6%, 0.8%) suffered sulfate attack (3 d), carbonation (3 d) and freeze-thaw cycles (25 times, 50 times, 75 times) in turn. The mass loss and relative dynamic elastic modulus of concrete samples were measured. The pore structure evolution was monitored by industrial CT (computer tomography). The results show that the durability of nano-modified concrete with particle size of 15 nm is better than that with particle size of 30 nm in general. Compared with nano-TiO2, the improvement of nano-SiO2 modified concrete is better. The damage of 15 nm-SiO2 concrete with 0.6% content is less, which can improve the internal structure of concrete better. During the process of sulfate attack, carbonation and freeze-thaw cycles, the porosity of 15 nm-nano-SiO2, 30 nm-nano-SiO2 and 30 nm-nano-TiO2 modified concrete generally decreases firstly and then increases. With the increase of freeze-thaw cycles, the pore structure evolution of all nano-particles modified concrete samples have the same regulation. The volume proportion of pores (≤0.01 mm3) decreases monotonously, while the volume proportion of pores (>10 mm3) increases generally. © 2022, Materials Review Magazine. All right reserved.