Study On Properties Of Graphene Oxide Modified Cement-based Composites Materials

There are lots of micro pores in the cement-based composites materials after molding,resulting in poor flexural strength and impermeability.In engineering,the flexural strength,durability and toughness can be improved by adding steel,fiber and other materials inside,the strengthening and toughening effect mainly depends on the reinforcement of the materials itself.It has no effect on the structure and compositions of cement-based composites materials.Therefore,the inherent problems of cement-based composites materials still exist.Graphene is a nanomaterial with special two-dimensional network structure.Its surface area is large and the mechanical properties are excellent.Graphene oxide has almost the same properties as graphene.It is easier to disperse in water than graphene because of carrying oxygen functional groups.In this paper,GO was incorporated into cement-based materials to study its effects on mechanical properties,durability and microstructure of cement-based composites materials.The mechanism of modification was discussed and analyzed.The main contents and conclusions are as follows:（1）The basic mechanical properties and fracture properties of GO modified cement-based composites materials were studied by adding GO into cement mortar.By testing its flexural strength and compressive strength,it was found that the flexural strength and the compressive strength increased with the increased of GO content.Through three point bending fracture test,the fracture properties of GO modified cement-based composites materials were studied.The results showed that GO improved the crack mouth opening displacement,the effective crack length,the fracture influence factors and toughness of the cement-based composites materials.（2）Durability of GO modified cement-based composites was studied by freeze-thaw,carbonation,chloride ions attack and sulfate attack.The results showed that GO enhanced the abilities of cement-based composites materials to resist freezing,CO₂,chloride and sulfate ions,it is indicated that the incorporation of GO improves the durability of cement-based composites materials.（3）The microstructure and compositions of GO modified cement-based composites materials were analyzed by scanning electron microscopy,thermogravimetric and X-ray diffraction,et al.The results showed that the structure of cement hydration products after adding GO is dense and orderly,the connection is close and the porosity decreased.The hydration degree of cement was increased,the C-S-H content of the hydration product was increased,and the content of AFt and porosity were reduced,which was consistent with the mechanical properties test and durability test results.