Study On Alkaline Resistance Of Basalt Fiber And Glass Fiber And Bending Properties Of TRC

As a new type of reinforcing material,fiber mesh is widely used in many fields due to its excellent performance.However,in the alkaline matrix of concrete,the fiber mesh is susceptible to corrosion easily,that lead to the strength of fiber and the long-term alkaline resistance of the concrete member decreases,which the application and use of fiber mesh is very limited.Therefore,it is of great significance to study the alkali resistance of fiber mesh for the analysis of its long-term alkali resistance in components.Compared with reinforced concrete,textile reinforced concrete has the advantages of corrosion resistance,light weight and so on,but fiber mesh is usually brittle material,which results in brittle failure characteristics of TRC members under load,that cannot meet the requirement of structural ductility requirements in engineering.In order to solve these problems,this paper does the following research:(1)The alkali resistance of the glass and basalt fibers were studied by using the SEM,EDS and IR techniques.The surface micro morphology,elemental changes and chemical molecular structure changes of the fibers before and after corrosion in NaOH solution were analyzed.The results show that the internal network skeleton structure of the basalt fiber and glass fiber corrosion mechanism are silicon oxide skeleton.When corroded in an alkali solution,both are OH~-damaged Si-O bonds,resulting in corrosion damage on the surface of the fiber.The Zr element content affects the alkali resistance of the glass fiber,and the higher the Zr element content,the better the alkali resistance.High zirconium glass fiber has the best alkali resistance,followed by alkali-resistant glass fiber,and medium alkali glass fiber is the worst.(2)Accelerated aging experiment and flexural experiment were conducted to investigate the long-term alkali resistance of basalt fiber mesh and glass fiber mesh reinforced concrete,which provide the basis for selecting mesh reinforcement materials.The results showed that before and after accelerated aging,the addition of basalt and glass fiber mesh all can improve the flexural strength of concrete sample but have little influence on the flexural strength at cracking.The long-term alkali resistance of basalt fiber mesh is similar with alkali-resistant glass fiber.It can be used as reinforcement material in concrete components.(3)The influence of the number of textile layers,the types and volume content of short fibers,length-diamond ratio of short steel fiber on the bearing capacity of TRC thin platesare investigate by means of four-point bending tests.The results show that with the increase the number of textile layers,the peak load tend to increase,bending toughness and creaking patterns are improved.Compared with the concrete specimen without short cut fiber,the ultimate bearing capacity and toughness of the thin plates can be improved by adding steel fiber alone,and the higher the content of steel fiber is,the more remarkable the effect is.When the volume content is 1.0%,the ultimate bearing capacity is increased by 60%.length-diamond ration of short fibers has little influence on the bearing capacity.Polypropylene fiber alone has little influence on the ultimate bearing capacity and toughness of the sheet,and the content of polypropylene fiber should not be higher than 0.1%.Hybrid ues of steel fiber and polypropylene fiber shows significant positive synthetic effect.