Preparation And Property Of GO-PC Compound High Performance Concrete

Graphene oxide(GO)has a wide prosperity in cement based materials and concrete which can improve the strength of cement based materials and concrete for the excellent mechanical property.But the dispersion of GO sheets in concrete hinder the further application.Based on cement paste and concrete,this thesis mainly research the application of GO in cement paste and concrete since the excellent mechanical property that GO owned.The GO solution and graphene oxide/polycarboxylate superplasticizer(GPC)were prepared as well as the C60 high performance concrete.With an elastic modulus of 130 GPa,extremely large surface area and at the same time with two-dimensional laminar nano structure,it's difficult for graphene to disperse uniformly in gel material because of the large steric hindrance.In this thesis,graphene oxide was copolymerized with monomers of polycarboxylate superplasticizer,so that the GO sheets can distributed uniformly in cement paste and concrete.The principle is that the polycarboxylate superplasticizer belongs to an anionic surfactant which can absorb to the cement particle uniformly.As a result,the GO sheet,together with polycarboxylate superplasticizer(PC)molecule,will be taken to cement particle homogeneously.The conclusions of this paper expounds in the following three parts:(1)Preparation of graphene oxide solutionThe prepared GO was characterized by FTIR,X-ray diffraction and transmission electron microscopy.And through the study of influence to the oxidation extent of GO when changing the amount of potassium permanganate,we can conclusion that:when conditions of the oxidation of graphene was controlled stirring for 2 hours at 10?,then6 hours at 35?,and stirring under the condition of 80?for 30 min,the synthesis of graphene oxide layer range from single-layer to multi-layer;The oxidation degree of graphene oxide was improved as the oxidation reagent increased.(2)Preparation of the graphene oxide/carboxylate superplasticizer compositeA series of tests such as FTIR,TGA,~1H-NMR and TEM,and fluidity of cement paste were conducted.The influence of GO content,monomer ratio and GPC dosage to the cement fluidity of GO-PC composite cement paste was explored.And the stability of GPC was analyzed.From above,the conclusion is that:the long chain of polycarboxylate superplasticizer was successfully composited on graphene oxide flake structure,mainly connected through hydrogen bonding and ester bond;When the dosage of the GO was below 2.0%,the water reducing rate of GPC rise with the dosage of GO.But when the dosage was below 2.0%,the water reducing rate of GPC would decline;When the ratio of AA:MAD:TPEG was 2:2:1,the effect of GPC composite on fluidity of cement was the best;when the GO was copolymerized together with monomers,the stability of GPC is the best which can be stored for a long time and keep evenly dispersed;The saturated dosage of GPC was 0.8%when solid content was 20%.(3)Preparation of GO-PC high property concreteIn this portion,the GO-PC compound reinforced cement paste and GO-PC compound concrete was prepared.And the work ability of GO-PC compound cement paste and GO-PC compound concrete was analyzed by testing the fluidity of cement paste and slumps of concrete.The conclusions are:graphene oxide doped in the cement paste and concrete can improve mechanical properties of hardened cement paste and concrete,and the improving effect was better to hardened cement paste than to concrete;The best dosage of GO in reinforced cement paste was 0.016%to cement.Silica fume has a synergistic improving effect to the GO-PC compound reinforced cement paste.