Research On The Performance Of Bundle Spliced Basalt Fiber Concrete

Fiber reinforced concrete is a kind of cement-based composite material with crack resistance,reinforcement and toughening effect,which is widely used in the field of civil engineering.However,the traditional short cut basalt fiber has smooth surface and poor adhesion with cement matrix,which restricts its large-scale application.In this paper,the bundle spliced basalt fiber with strong grip and good dispersion is selected as the fiber reinforcement material.The research on the bundle spliced basalt fiber concrete and its high-performance application technology is of great significance to promote the application of basalt fiber in concrete.In this paper,the mechanical properties and alkali resistance of different kinds of basalt fibers are compared,and the effects of the basic properties of basalt fibers and their types and lengths on the mechanical properties of mortar are studied;C50 concrete was poured by bundle spliced basalt fiber,and the effects of fiber content on the working performance,mechanical properties and durability of concrete were studied;The ultra-high performance concrete is poured by using bundle spliced basalt fiber,the optimal content and its influence law are put forward,and the reinforcement mechanism of bundle spliced basalt fiber in concrete is revealed.The main results are as follows:（1）The tensile strength of bundle spliced basalt fiber is better than that of short cut basalt fiber,and the adhesion between bundle spliced basalt fiber and matrix is stronger,but the alkali resistance is lower than that of short cut basalt fiber.The improvement effect of basalt fiber on mortar strength at 1%volume content:SCBF-Ⅱ>BSBF>SCBFⅠ.Incorporation of BSBF can increase the flexural toughness index of mortar by 5.5 times,and short cut basalt fiber has no obvious benefit on the toughness of mortar.（2）With the increase of BSBF content,the slump of concrete gradually decreases,and the mechanical properties show a trend of increasing first and then decreasing.The optimal content of fiber is 0.3%.At this time,the compressive strength,splitting tensile strength,flexural strength and flexural toughness index increase by 10.39%,61.16%,13.33%and 50.85%respectively.（3）With the increase of BSBF content,the chloride ion penetration resistance and shrinkage resistance of concrete are significantly enhanced.When the fiber content is 0.3%,the 6h cumulative electric flux is reduced by 5.91%and the shrinkage rate is reduced by 18.78%.The frost resistance and sulfate resistance of concrete are slightly enhanced,and the addition of BSBF can delay the decline rate of relative dynamic elastic modulus in the process of freeze-thaw cycle.When the concrete is corroded by sulfate,the decline rate of corrosion resistance coefficient decreases by 2.14%.The addition of fiber can change the internal pore structure of concrete,form a threedimensional network structure in the concrete and enhance the compactness of concrete.（4）With the increase of BSBF content and length,the fluidity of UHPC decreased gradually,and the mechanical properties increased first and then decreased.The optimum content of BSBF in UHPC is 1%,the optimum length is 12mm,the fluidity reaches 200mm（high flow concrete）,the compressive strength increases by 31.02%,the flexural strength increases by 18.31%,and the toughness index increases by 10.21 times.High temperature curing system can reduce the porosity of UHPC,but the proportion of harmful pores increases significantly,and has no significant effect on the strength of UHPC enhanced by BSBF.The addition of BSBF can promote the hydration reaction of UHPC,and the bond between BSBF and UHPC matrix is close without obvious interface transition zone.