Dispersity Of Graphene And Properties Of Cement Mortar

Graphene is an emerging carbon nanomaterial.Adding graphene to cement-based materials can play the roles of filling,bridging and template,etc.Therefore,it has attracted extensive attention from researchers at home and abroad in recent years.Using the characteristics of graphene,adding it to cement-based materials can play a role in strengthening and toughening,and improve the defects of cement-based materials such as low toughness and high brittleness,which has important engineering application value.In view of the easy agglomeration of graphene,this paper studied the dispersion of graphene,optimized the Surface active agent(SAA)suitable for dispersive graphene,and studied the mechanical strength and dry shrinkage characteristics of graphene cement mortar.The main research contents are as follows:(1)The critical micelle concentration of each SAA was measured through the surface tension test,so as to determine the experimental concentration of the graphene dispersion in this paper.Polycarboxylic acid water reducer(PC),sodium cholate(SC),polyoxyethylene nonylphenyl ether(C0520),sodium dodecylbenzene sulfonate(SDBS)and cetyltrimethyl ammonium bromide(CTAB)were observed and optimized by static test of graphene dispersion solution,and UV/visible photometer was used.The SAA suitable for dispersing graphene in this paper are PC,SDBS and CTAB.(2)The distribution of graphene in graphene cement mortar was tested and analyzed by surface scanning of Energy Dispersant Spectrometer(EDS),and it was found that the carbon element in the PG-3 group(PC as dispersant and graphene content was 0.03%)was the most uniform and the highest density.However,the non-uniform distribution of carbon elements can be observed in the graphene dispersion of other SAA groups due to the existence of pores.Meanwhile,it is found that although the addition of defoaming agent improves the pore structure and mechanical strength of mortar,the distribution of carbon elements in the specimen is still not uniform.(3)The cement mortar was mixed with SAA and graphene,and the mechanical strength,shrinkage characteristics,fluidity and water absorption of the cement mortar were studied.The optimum dosage of graphene was determined when the mechanical strength and dry-shrinkage characteristics of graphene cement mortar reached the optimum under different SAA effects.The best SAA type to improve the performance of graphene cement mortar was determined by the performance variation rule.(4)Scanning electron microscopy(SEM)and X-ray diffraction(XRD)were used to test graphene cement mortar,and to explore its enhancement mechanism to cement mortar.SEM analysis shows that the hydration products in the graphene cement mortar increase,indicating that the addition of graphene changes the pore structure of the hydration mortar.XRD test also found that the hydration products increased in the graphene cement mortar,but the addition of graphene did not generate new phases in the mortar.