Experimental Study On Early Crack Resistance And Basic Mechanicalproperties Of Hybrid Fiber Reinforced Concrete

Hybrid fiber concrete is a composite building material formed by blending two or more fibers into concrete.Basalt fiber is called a new environmentally friendly fiber in the 21 st century.It has good physical and chemical properties.Plastic steel fiber is also called imitation steel fiber.It is a polypropylene fiber with light weight,high strength and high toughness,and has the physical properties of steel fiber and synthetic fiber.Steel fiber has many shortcomings such as rust,high price and large specific gravity compared with plastic fiber.Therefore,plastic fiber is the fiber that may replace the development trend of steel fiber in the future.Based on the material properties of the above fibers,the experimental and theoretical analysis of the early crack resistance and basic mechanical properties of basalt fiber and plastic fiber fiber hybrid concrete are studied.The main contents are as follows:(1)By using basalt fiber and plastic fiber fiber length,dosage,and coarse aggregate particle size as experimental factors,each factor takes three levels for 5 factor 3 horizontal orthogonal experiment,in which basalt fiber length and length of plastic steel fiber And the amount of basalt fiber volume is 0.05%,0.1%,0.15%,respectively.The effect of hybrid fiber on the early crack resistance of concrete is studied.The experiment found that the hybrid fiber has better crack inhibition effect.Among them,basalt fiber can effectively reduce th e plastic shrinkage crack of concrete,and plastic steel fiber can effectively reduce the plastic settlement crack of concrete.(2)Perform slump test on each concrete of orthogonal experiment and use the data for orthogonal analysis to obtain the relation ship between fiber cracking effect and slump,and analyze the factors affecting slump.The experiment found that: basalt fiber It has a significant effect on the reduction of concrete slump.(3)The influence of the widely used basalt fiber and the new sur face-stained steel fiber test fiber on the compressive strength and splitting tensile strength mechanical properties of concrete under single mixing and mixing,wherein the basalt fiber content is 0.15 %,0.1%,0.1%,the corresponding length is 12 mm,20mm,30mm;the plastic fiber content is 5kg / m3,the length is 30 mm,40mm,50 mm.Through the analysis of the results of compression and splitting tensile tests of single-mixed and mixed concrete,the experimental group with mixed effect and the influence of f iber content and fiber length on the confounding effect were obtained.The experiment found that for the tensile strength,the hybrid fiber is prone to positive mixed effect,and for the concrete compressive strength,only a small part produces a positive mixed effect.