| The incorporation of two or more kinds of fibers into the concrete matrix is a relatively comprehensive method to improve the performance of concrete.Nowadays people’s awareness of environmental protection is increasing,and the application of plant fiber in concrete materials has been paid attention to.Therefore,in this paper,the new basalt fiber with high elastic modulus and sisal fiber with low elastic modulus are selected to carry out the performance test research of hybrid fiber concrete by combining the methods of experimental research and theoretical analysis.Firstly,the basic mechanical properties of concrete containing 4 kinds of sisal fiber content(1kg/m~3,2kg/m~3,3kg/m~3,4kg/m~3)and 4 kinds of basalt fiber content(1.5kg/m~3,3kg/m~3,4.5kg/m~3,6kg/m~3)were tested.Secondly,the test of chlorine salt erosion resistance and drop hammer impact resistance of fiber reinforced concrete were carried out,and the microscopic analysis was carried out by SEM.(1)The basic mechanical test shows that the compressive strength of concrete cube is the best when adding 3kg/m~3 basalt fiber or 2kg/m~3 sisal fiber,which increases by 5.3%and 3.6%respectively.When adding 4.5kg/m~3 basalt fiber or 3kg/m~3 sisal fiber alone,the splitting tensile strength of concrete cube is the best,which increases by 14.45%and17.58%,respectively.Mixed with 3kg/m~3 basalt fiber and 2kg/m~3 sisal fiber,the statics improvement effect of concrete is the best,the compressive strength of the cube is increased by 10.3%,the tensile strength is increased by 22.42%,and the mixing effect is good.(2)The chlorinated salt erosion resistance test of mixed fiber concrete for 60d,120d and 180d shows that when 2kg/m~3 sisal fiber is mixed with 3kg/m~3 basalt fiber,the concrete has the lowest pressure resistance loss rate,the lowest mass loss rate and the best erosion resistance performance at different ages.The mass loss rate of 120d and 180d chlorine salt erosion test blocks was measured,and it was found that the mass loss rate of concrete with fiber was lower than that of ordinary concrete.(3)It can be seen from the drop hammer impact test that the impact resistance of fiber reinforced concrete has been improved,and the failure characteristics have changed significantly.The impact resistance energy difference of sisal fiber concrete mixed with6kg/m~3 or 4kg/m~3 is increased greatly,the initial crack energy difference is increased by107.7%and 115.4%,and the final crack energy difference is increased by 95.2%and195.1%,respectively.When the concrete is mixed with 3kg/m~3 sabre fiber and 2kg/m~3sisal fiber,the difference of impact resistance energy increases by 1.29 times,showing the failure characteristic of"multi-crack cracking".(4)According to SEM microscopic findings,a large amount of hydration products are attached to the fiber surface and bonded well with the test block.Both kinds of fibers can prevent the appearance and expansion of concrete cracks and improve the integrity of concrete.From the analysis of concrete hydration degree,it can be seen that the hydration degree of fiber reinforced concrete is higher than that of ordinary concrete,and the density degree is improved.Figure 50 Table 12 References 79... |
