Study On The Performance Of Reinforced Concrete By Adding Glass Fiber And Basalt Fiber

Concrete is an irreplaceable basic material in contemporary architecture,but because of its brittleness and poor durability,it also restricts the development and application of actual construction.Based on the idea of "compounding" in the field of material science and previous research experience,this paper chooses basalt fibers and glass fibers as admixtures for concrete compounding.It is hoped that by adding these two kinds of fibers into the base concrete,they can play their respective advantages in concrete,and obtain fiber concrete with better performance and stronger mechanical properties.Basalt fibers have the advantages of high strength and good toughness,and glass fibers have the advantages of good mechanical properties and corrosion resistance,They can complement the defects of concrete in performance.In this paper,12 mm short-cut basalt fibers and glass fibers are mixed into concrete according to the volume fractions of 0.05%,0.1%,0.15% and 0.2%,respectively,to make fiber reinforced concrete of different fibers content.At the same time basalt fibers and glass fibers were mixed into concrete according to the volume difference of 0.2% and 0.05% of the total volume to produce mixed fiber reinforced concrete of different proportions.In this paper,from the macroscopic point of view,the slump tests of reference concrete,basalt fiber reinforced concrete,glass fiber reinforced concrete and mixed fiber reinforced concrete are carried out respectively.From the changes of their fluidity and cohesiveness,it is found that the working performance of fiber reinforced concrete is better than that of reference concrete;the compressive and splitting tensile strength of fiber reinforced concrete in three age periods of 3 days,7 days and 28 days are strengthened.The three-point bendingstrength of these concrete at 28 days of age was tested.The change of mechanical properties of fiber reinforced concrete and its causes were analyzed from the test results.The test results show that:(1)After mixing fibers,the slump of fiber reinforced concrete has a significant downward trend compared with that of reference concrete.And in the slump test of single fiber concrete,with the increase of fiber content,the slump decreases more.The slump of mixed fiber reinforced concrete is lower than that of single fiber reinforced concrete.From the results of slump test,it can be concluded that the addition of fibers can effectively reduce the fluidity of concrete,thereby improving the performance of concrete.(2)In the compression and splitting tensile tests at different periods,basalt fiber reinforced concrete and glass fiber reinforced concrete have increased significantly compared with the reference concrete,and show a trend of increasing first and then decreasing.Comparing the results of different ages with the same fibers adding content,it can be seen that the compressive and splitting tensile strength of fiber reinforced concrete in earlier age is stronger than that in the late age.The optimum adding content of basalt fiber reinforced concrete is 0.1%,and that of glass fiber reinforced concrete is 0.15%.The results of three-point bending tests of 28 days age are basically consistent with those of compression and splitting tests.It can be concluded that with the addition of fibers,the fine cracks and holes in concrete can be filled effectively,and a part of the stress can be shared when the concrete is subjected to load,so that the fiber concrete shows better mechanical properties.(3)From the results of mechanical tests on fiber reinforced concrete,it can be seen that mixed fibers reinforced concrete can improve the mechanical properties of concrete better than single fiber reinforced concrete,and the optimum ratio of the two fibers is 0.1% volume fraction of basalt fibers and 0.1% volume fraction of glass fibers.Because of the three-dimensional random distribution of two kinds of fibers in mixed fibers reinforced concrete,the concentrated stress at the crack tip is reduced when the concrete is under pressure,resulting in a gain effect.(4)When using SEM to observe the micro-structure of fiber reinforced concrete,it canbe found that the surface of cellulose in fiber reinforced concrete has formed aggregated hydration through hydration reaction,which shows effective bonding between concrete and fibers,thus enhancing the mutual bonding,and has a great role in improving the mechanical properties of concrete.