STUDY ON THE NANO-HARDNESS OF THE INTERFACIAL TRANSITION ZONE OF RECYCLED CONCRETE WITH GRAPHENE OXIDE

摘要

The nano-hardness of the interfacial transition zones of recycled concrete with graphene oxide were studied by using nanoindentor. The results showed that the average hardness and width of the interfacial transition zone of recycled concrete with graphene oxide between new paste matrix and natural aggregate were about 0.84GPa and 30-35μm, respectively; The hardness and width of the interfacial transition zone between new paste matrix and old paste matrix was about 0.76GPa and 25-30μm, respectively. Compared with ordinary recycled concrete, it was found that the proportion of calcium silicate hydrate and the content of calcium hydroxide crystal group in the hydrate were enhanced. The nano indentation hardness distribution in the interfacial transition zone were more uniform and the microstructure was more stable. According to the relationship between the microscopic mechanical properties and the macroscopic mechanical properties of recycled concrete, it can be concluded that graphene oxide can enhance the mechanical properties and microstructure of the interfacial transition zone of recycled concrete so as to improve the macroscopic mechanical properties of recycled concrete.