Study On Integrated Molding Of Chimney Lining And FRP-concrete Interface Strength And Durability

Thermal power generation plays an important role in the country’s power energy structure,and the most important building is the chimney.Thermal power generation will produce a large amount of SO2,SO3,NO harmful gases and cause serious pollution to the environment.After desulfurization,the temperature and humidity inside the chimney are high,and the flue gas is dissolved in water and adheres to the inner wall of the chimney,causing serious corrosion to the chimney.Fiber-reinforced resin matrix composite(FRP)has the characteristics of light weight,corrosion resistance,and long service life,making it an ideal choice for chimney lining materials.The winding process is commonly used in the preparation of chimney linings at home and abroad,but the production cost of this method is too high and can not be constructed on site.It is an important task to study a low-cost,on-site construction process.The FRP lining is tightly attached to the inside of the chimney tube wall and uses its excellent corrosion resistance to protect the concrete tube wall.However,FRP does not match the concrete and has poor bonding performance.The interface degradation behavior in the chimney working environment severely restricts the service life of the chimney.Therefore,this article focuses on the following researches on the basic mechanical properties and durability of FRP-concrete structures in special environments,:and did the following research:(1)A new technology of in-situ integral forming of composite lining of large-diameter chimney was developed.A complete equipment system was built and a chimney structure was made.The temperature and pressure system parameters are designed according to the characteristics of the resin used,and the airbag is used to assist pressurization and heating,and successfully manufactured FRP lining(2)Two fiber-reinforced composite materials with different substrates were prepared by hand lay-up method,and placed in a humid heat aging,high and low temperature cycle environment to study the influence of the environment on the basic mechanics of the composite material.The study found that the overall mechanical properties of GF/EP(Fiber reinforced epoxy resin composite)are better than that of GF/VE(Fiber-reinforced vinyl composite material),but the degradation rate of tensile strength and flexural strength of GF/VE under humid heat aging and high and low temperature cycling environments is less than that of GF/EP;For both materials,the degradation rate of bending strength is higher than the tensile strength.The reason is that the expansion of the fiber and the resin does not match,and internal stress is generated in the bonding surface of the fiber and the resin at high temperature,which reduces the interlaminar shear strength of the material.(3)The ultimate bearing capacity of FRP concrete structure under mode I fracture and mode II fracture was tested,and the interfacial bond strength was calculated and compared.The results show that the interfacial strength of the same specimen under mode Ⅰ fracture is higher than that under modeⅡ fracture;The interface strength of EP-based FRP-concrete composite is higher than that of VE-based FRP-concrete composite.(4)The effect of FRP sheet and concrete bonding performance under high and low temperature cycle and sulfuric acid corrosion environment was tested and studied.The interfacial strength was characterized by splitting tensile test and shear test.The results showed that as the erosion time increased,the interfacial strength continued to decrease,and the order of the influence strength was the coupling environment of high and low temperature cycles and sulfuric acid erosion>sulfuric acid erosion>high and low temperature cycles.In the accelerated corrosion process in the laboratory,the mechanical properties of composite materials have a small decrease,and various performance indicators can still reach more than 90%of the standard.Therefore,composite materials as the main material of the chimney lining can effectively resist the erosion and damage of the external environment and meet the long-term Service conditions.Through the research of this article,it provides valuable reference for the integrated molding technology of FRP lining and the durability of composite chimney lining,and provides beneficial theoretical and experimental support for the development of fiber-reinforced composite materials as chimney lining.