Experimental study on mechanical property and pore structure of nano-modified concrete in the large temperature difference environment of cold-region tunnels

To reveal the mechanism of nanomaterials on concrete in the large temperature difference environment, three different types of nano-modified concrete were explored in this study. The mechanical properties and pore structure characteristics of concrete under these different nano-modified measures were investigated. Furthermore, mathematical models of the strength and the pore structure were established. The experimental results demonstrate that: Untimely entering the large temperature difference environment is unfavourable for the strength of concrete; The incorporation of nanomaterials is conducive to the strength and pore structure of concrete, of which 2 % Nano-SiO2 2 shows the best effect; When the pre-curing time ranges from 1.5 days to days, the strength of 2NS group develops slowly, which is consistent to the change of pore structure; The multi factor strength mathematical model established can express the quantitative relationship between concrete's strength and pore structure.