Mechanical Properties and Pore Fractal Characterization of Graphene Oxide–Modified Concrete after High Temperatures

Fractal theory is a vital tool emerging in recent years for studying self-similarity in complex systems. This paper incorporated graphene oxide (GO) nanosheets into concrete to study the variation rule of high-temperature mechanical properties of graphene oxide–modified concrete (GOC) with the help of fractal theory. It is found that the fractal dimension of pores is a parameter that can accurately reflect the pore distribution characteristics of concrete. The concrete strength model established based on fractal dimension is strongly associated with the experimental results. The shrinkage of calcium silicate hydrate (C─ S─ H) gel fibers under high temperatures leads to an increase in the internal pore space of concrete and a decrease in the fractal dimension. At 800°C, the average fractal dimension of each group increased by 15.69% compared with room temperature. GO can slow down the destruction of the C─ S─ H network by high temperatures, thereby improving the heat resistance of concrete. The average strength of the GOC group at 600°C was 123.54% that of the PC group.