Study On Durability Of Cement-based Materials Mixed With Nano-fillers

In recent years,with the acceleration of offshore wind energy development,my country has installed a large number of wind power installations in coastal areas,and the durability of its foundation concrete has attracted much attention.Due to the existence of a large number of harmful ions such as chloride ions and sulfate ions in the seawater,they erode the foundation reinforced concrete of wind power equipment for a long time,which not only reduces the service life of wind power equipment,but also increases maintenance costs.Therefore,it is of great theoretical significance to study how to enhance the durability of concrete in marine environment.In this paper,the cement matrix is compounded with new functional materials to improve the corrosion resistance of the wind power foundation concrete matrix to achieve the goal of improving its durability.Due to the large specific surface area,large proportion of surface atoms,high surface energy and small particle size of nano materials,they have the properties of quantum size effect,surface effect,macro quantum tunneling effect and small size effect which are not found in general materials.The thesis conducts indoor experiments with composite nano-fillers and other functional fillers,analyzes the test data,and discusses the influence mechanism of nano-functional materials on the physical and mechanical properties and durability of wind power foundation concrete matrix.The main research is as follows:1.Through orthogonal experiments,the optimum conditions of water binder ratio of 0.35,0.40,0.45,basalt fiber(BF)content of 0.05%,0.10%,0.15%,nano silica(NS)content of 0.5%,1.0%,1.5%,alumina powder(Al2O3)content of 2.5%,5%,7.5%were studied,the fluidity,compressive strength and flexural strength of the mortar mixed with nano-functional materials are affected by the law and mechanism.The research results show that the fluidity of cement mortar mixed with NS decreases with the increase of the amount.The compressive strength of cement mortar mixed with 1.0%NS for 7d and 28d increases by 5.8%and 8.03%coMPared with cement mortar mixed with 0.5%NS.2.Through coMParative experiments,the influence of graphene(NGPs)on the mechanical properties of cement mortar was studied,and the microscopic analysis methods such as SEM and XRD were used to explore the microscopic mechanism of NGPs enhancing cement hydration products.The test results show that the compressive strength of cement mortar mixed with 0.03%NGPs increased by 22%and 45%at 7d and 28d,respectively.It can be seen from the SEM image that a large number of dense lamellar structure crystals are formed inside the cement matrix,and the XRD pattern shows that no new phases are formed.This is mainly due to the large specific surface area of NGPs,which fully absorbs free water in the matrix,and hydrates.Produce dense crystals.3.Through orthogonal experiments,the influence of different dosages of BF,NS and Al2O3 on the resistance of concrete to chloride salts was studied under the water-binder ratio(0.40).Studies have shown that adding 1.0%NS can fill the internal pores of concrete,and react with calcium hydroxide to form crystals to enhance the compressive strength of the test block.Too much content will cause uneven dispersion,reduce the compactness of the test block,and reduce the strength.4.Study the effect of different dosages of BF,NS and Al2O3 on the sulfate resistance of concrete.The study found that the relative dynamic elastic modulus and compressive strength of concrete mixed with Al2O3 and BF increased with the increase of the content;it showed an upward trend with the extension of the immersion time;and the mass loss rate first increased and then decreased with the extension of the immersion time.5.Study the effect of different dosages of BF,NS and Al2O3 on the chloride-sulfate resistance of concrete.The relative dynamic elastic modulus and compressive strength of NS-mixed concrete increased firstly and then decreased with the increase of the content,and the mass loss rate increased firstly and then decreased with the increase of immersion time.The optimal dosage is 1.0%.Figure 78 table 37 reference 87...