Research On Properties And Engineering Applications Of Cement-based Materials Enhanced By Graphene Oxide

Nanomaterials such as graphene oxide can significantly improve the microstructure,mechanical properties and durability of cement-based materials,and give them a lot of functional properties.However,studies showed that single-doped graphene could produce obvious thickening and coagulation effect on cement-based material,and reduce its working performance.For this purpose,considering the synergistic effect of mineral admixtures and graphene oxide,the flowing property and mechanical properties of cement-based material are studied systematically,and its engineering application is analyzed and discussed.The research results have certain scientific significance and reference value for improving the basic theory and applied research of the new cement-based material.The main research includes:(1)The mechanical properties of graphene oxide ontology play a decisive influence on the performance of the composite material,but because of the complexity of its electronic structure,the current research on its mechanical performance has not yet reached broad consensus.For this,based on the molecular dynamics method,the present paper created a graphene oxide atomic model containing hydroxyl,epoxy and carboxyl,which are distributed randomly,and the effect of variety and number of functional groups on elastic modulus,ultimate strength and ultimate strain of graphene oxide were studied.Furthermore,the correlation between the tensile strain rate and mechanical properties was studied.The results showed that the coverage of oxygen-containing functional groups had significant influence on the properties of graphene oxide.With the increase of coverage,the elastic modulus,ultimate strength and ultimate strain decreased gradually.With the increase of tensile strain rate,the elastic modulus,ultimate strength and ultimate strain of graphene decreased gradually(2)Aim at flowing property of cement-based material reinforced by mineral admixture and graphene oxide,considering the influence factors of oxidized graphene content,fly ash content and water-binder ratio,the mix scheme was created by using orthogonal experiment method.Based on the expansion test,the influence lawes of flowing property with each influencing factor were studied.The results showed that,flowing property decreased significantly with the increase of graphene oxide content,and flowing property firstly increased and then decreased with the increase of fly ash content which showed a certain critical effect,while flowing property increased with the increase of water-binder ratio.Based on orthogonal experiment variance analysis,it was showed that the graphene content,fly ash content and water-binder ratio had significant influence on flowing property.Furthermore,the range analysis results showed that the sensitivity of flowing property to influence factors,from large to small in order,were graphene oxide content,water-binder ratio and fly ash content.Based on experimental results,the relationship model of expansion and influence factors was obtained.(3)Aim at mechanical properties of cement-based material reinforced by mineral admixture and graphene oxide,the flexural and compressive properties were studied respectively.The results showed that the flexural properties of each age increased with the increase of graphene oxide content,and the flexural properties deceased with fly ash content,while that changed slightly with the increase of water-binder ratio.Based on range analysis of orthogonal experiment,the sensitivity of 1d flexural property to the influence factors,from large to small in order,were fly ash content,water-binder ratio and graphene oxide content,while that of 3d,7d,14 d,21d,28 d,49d and 63 d were fly ash content,graphene oxide content and water-binder ratio.The compressive properties of each age increased with the increase of graphene oxide content,and the compressive properties of each age decreased with the increase of fly ash content,while that decreased with the increase of water-binder ratio.The sensitivity of 1d compressive properties to the influence factors,from large to small in order,were fly ash content,graphene oxide content and water-binder ratio,while that of 3d,7d,14 d,21d,28 d,49d and 63 d were graphene oxide content,fly ash content and water-binder ratio.(4)Aim at synergistic effect of mineral admixture and graphene oxide on cement matrix,considering the flowing and compressive properties comprehensively,the optimal mixture ratio was analyzed based on the comprehensive balance method of orthogonal experiment.Based on experimental comparison and theoretical analysis,researches on dispersion,work performance,mechanical properties,hydration effects and dimensional coordination were conducted,which fully illustrated the synergistic effects of mineral admixture and graphene oxide on cement matrix.The advantages and disadvantages of this material were analyzed from the aspects of flowing property,mechanical properties,economy and functionality by comparing with the common grouting materials and PVA-ECC cement materials used in the current project.(5)Aim at the problems of appearing in short time,little engineering application of the material,based on the advantages of the material,the present paper put forward the reinforcement and repair plan,which was used in key parts of the special structure in line with the principle of using the best material at the key point.The injection reinforcement technique was proposed and the injection performance of the material was tested.For the evaluation of reinforcement effect,the successful evaluation model of the reinforcement project was created based on the albino weight function and the Delphi method,in which the first grade index was the success of the project,and the second grade indexes included safety,durability and economy,while the third grade indexes included the improvement of bearing capacity,overall deformation,durability of reinforced materials,bonding properties of old and new materials,direct cost reinforcement and indirect benefits.The strengthening case of desulfurization tower in a chemical plant showed the feasibility of this material for the key parts of special structures.