Study On Durability And Mechanical Properties Of Hybrid Fiber Reinforced Concrete

Insufficient durability of concrete has been a very serious problem in the field of construction engineering.In the course of nearly a hundred years of development,it has been found that the addition of metal fiber,synthetic fiber and other materials to the cement composite matrix can significantly enhance its durability and improve the service life of concrete.At present,the research on fiber hybrid concrete at home and abroad mostly focuses on hybrid fiber concrete such as steel fiber,polypropylene fiber,carbon fiber and basalt fiber.However,the cost of carbon fiber is huge,the polypropylene fiber elastic modulus is too low,the basalt fiber and concrete are not easy to be easily and the corrosion resistance is poor,which drives researchers to research new fibers.Polyvinyl alcohol fiber has the advantages of high elastic modulus,low cost,good mixing with concrete,etc.It is a kind of fiber with great research prospects at present.In view of the requirements of the basic mechanical properties and durability of concrete materials in harsh environments such as coastal areas and cold and humid,this paper selects steel-polyvinyl alcohol hybrid fiber concrete as the research object.(1)Determine the total volume fraction of three different fibers(0.2%,0.4% and 0.8%).Under the total volume ratio of each fiber,select a certain amount of steel fiber and polyvinyl alcohol fiber to be single-blended.Different proportions(1:3,1:6 and 1:9)are blended into the concrete.A total of 16 different test pieces were designed,namely,1 set of plain concrete,3 sets of steel fiber concrete,3 sets of polyvinyl alcohol fiber concrete,steel-polyvinyl alcohol mixed fiber concrete(three different total volume of incorporation)The next three different incorporation ratios are 9 groups.(2)The basic mechanical properties of the fiber-reinforced concrete specimens were tested for compressive strength,flexural strength and tensile strength.Analysis of the influence of different incorporation modes of steel-polyvinyl alcohol fiber,different fiber volume,and different mixing ratio on mechanical properties of concrete.The test results show that the compressive strength of the single-doped polyvinyl alcohol concrete will be slightly reduced,while the flexural and tensile strength will be increased.The concrete's compressive strength will be significantly improved in concrete or mixed with pva with a certain amount of steel fiber,and its flexural and tensile strength will also be significantly improved.(3)The durability tests of freeze-thaw resistance,chloride ion penetration resistance and sulfate corrosion resistance of fiber-reinforced concrete specimens are carried out,and the different fiber content and different mixing methods of steel-polyvinyl alcohol fiber were analyzed.The influence of different mixing ratios on the durability of concrete.The results show that the steel-polyvinyl alcohol blended fiber with a mixing ratio of 1:6 has the best effect on the chloride ion permeability of the concrete matrix.The steel-polyvinyl alcohol blended series of concrete with a mixing ratio of 1:3 generally exhibited better frost resistance.The anti-sulfuric ability of the blended series is significantly stronger than that of the single-mixed series.(4)Based on the experimental data and combined with the existing theoretical calculation models at home and abroad,the life prediction calculations of each group of steel-polyvinyl alcohol hybrid fiber reinforced concrete based on freeze-thaw cycles and sulfate corrosion were carried out.The results show that Steel fiber and polyvinyl alcohol fiber can improve concrete life under the environment of freeze-thaw damage and dry-wet cycle-sulfate corrosion.The blending of the matrix has a longer life extension effect than the single-mix series.