Dispersion Of Multi Walled Carbon Nanotubes And Its Modification Of Cement Based Materials

Cement-based materials have shortcomings such as self-weight,low tensile and flexural strength,high brittleness,poor crack resistance,etc.In order to overcome these problems,the new nanoscale fiber with high strength,high elastic modulus and high durability has been incorporated into cement-based materials to become a hot research direction for modification and improvement of its properties.Multi-walled carbon nanotubes(MWCNTs)are nanoscale fibers that can be used to manufacture multifunctional materials with excellent properties.Their incorporation into cement-based materials will significantly affect the microstructure and macroscopic properties of cement-based materials.This article explores the multi-walled carbon nanotubes on the properties of cement base material modification research,first find easy to reunite has a better dispersion stability of multi-walled carbon nanotubes dispersion process,and mixed with cement base material multi-walled carbon nanotubes in the mechanical properties and resistance to chloride ion diffusion performance,the influence of the performance of the final is multi-walled carbon nanotubes as a conductive material affect the performance of reinforced concrete protection of reinforcement,preliminary explore its electrical properties.First of all,through the quantitative characterization of the dispersion effect of different concentrations of carbon nanotubes dispersion solution,using ultrasonic and dispersant composite dispersion process,the absorbance of the index to characterize,through the single and compound mixing of two kinds of dispersants,determine the linear relationship between absorbance and concentration.After using different ratio of1:2,1:4,1:6,1:8 for dispersed carbon nanotubes solution,to determine the optimum dispersant for PVP and PC mixed combinations and MWCNTs: the proportion of dispersant 1:4,and combining the qualitative analysis and static TEM observation,TEM can see only mechanical agitation for processing of carbon nanotubes is in a state of reunion,after the compound dispersion technology of ultrasonic + dispersant dispersed carbon nanotubes solution after see no winding together.Finally,the dispersant was added into cement-based materials alone to explore the influence of dispersant itself on cement-based materials.The results showed that the dispersant had no effect on the mechanical properties of cement-based materials.The cement mortar and concrete specimens were prepared from the well-dispersed carbon nanotube dispersion solution,and the mechanical properties of carbon nanotube cement-based materials were explored by means of splitting tensile strength,compressive strength,flexure strength,SEM and FESEM microscopic tests.The results show that the mechanical properties are the best when the content of carbon nanotubes is about 0.1%.Through microscopic detection,the incorporation of carbon nanotubes refined the cement-based structure,reduced the tendency of crack expansion,and produced a good connection in cement-based materials,and improved the tensile properties of cement-based materials.Explores the concrete chloride ion diffusion resistance of carbon nanotubes research,takes the form of natural soaking,soak 0-180 d,experiments show that the addition of multi-walled carbon nanotubes can enhance the performance of the resistance to chloride ion diffusion and microscopic detection combined with micro pressure mercury MIP experiment,XRD and MIP experiment found that the incorporation of multi-walled carbon nanotubes can make concrete refine pore,increasing the compactness,reduce the total porosity,reducing the generation of cracks and expansion.XRD spectra showed that the incorporation of MWNTs did not generate new phase,which promoted the generation of hydration products,which further filled the internal pores and increased the compactness.Multi-walled carbon nanotubes reinforced concrete reinforcement performance research,from the perspective of the nondestructive testing,the specimen to chlorine salt immersion and electrochemical workstation test,under the different soaking age from polarization curve and potential,corrosion current density,electrochemical parameters,such as adding carbon nanotubes would make the corrosion current density and corrosion potential is reduced,the dosage,the greater the change is more significant,the polarization curve,the join carbon nanotubes,curve move towards the direction of the negative potential and corrosion current increases.At the same time,after the phase immersion,the broken steel bar was photographed and observed to observe the morphology of accelerated corrosion of steel bar by carbon nanotubes.The results show that carbon nanotubes,as excellent conductive nanomaterials,and steel and cement-based materials can form galvanic cells,thus accelerating the corrosion rate.And the potential difference between carbon nanotubes and steel,accelerate the formation of macro batteries,accelerate the corrosion of steel.This paper has 51 pictures,26 tables and 107 references.