Experimental Study On Flexural Behavior Of Alkali-activated Sea Sand Concrete Beam With BFRP Bars

With the development of Chinese social,river sand resources have gradually decreased or even begun to show the trend of resource depletion.In order to solve the problem of lack of resources caused by over-exploitation of river sand,this paper uses sea sand as fine aggregate in replacement of river sand.Furthermore,alkali-activated concrete is used to replace ordinary concrete,and steel bars are replaced by BFRP bars to improve the basic performance of the sea sand concrete.Three new environmentally friendly materials,such as sea sand,alkali-activated concrete and BFRP bars,were used to construct a new structural system— the basalt reinforced alkali-activated sea sand concrete.This paper attempts to use two new environmentally friendly materials with high corrosion resistance to solve the corrosion problem of ordinary concrete with steel bar in the reef environment.This paper has done the following research:(1)Through the experimental study on flexural behavior of alkali-activated sea sand concrete beam with BFRP bars,the ultimate flexural capacity,failure mode,crack width,and deflection distribution of BFRP reinforced alkali-activated sea sand concrete beams with different reinforcement ratios were obtained.In this paper,the flexural behavior of BFRP reinforced alkali-activated sea sand concrete beams and the flexural behavior of reinforced alkali-activated sea sand concrete beams were compared and analyzed,and observing the similarities and differences of the flexural behavior of alkali-activated sea sand concrete with different reinforced materials.The results show that the ultimate flexural capacity of BFRP reinforced alkali-activated sea sand concrete beams increases with the increase of reinforcement ratio,but the cracking load is not much different.Once cracked,the cracks will proceed directly to a higher place.With the same reinforcement ratio,the ultimate flexural capacity of BFRP reinforced alkali-activated sea sand concrete beams is not much different from the ultimate flexural capacity of reinforced alkali-activated sea sand concrete beams.The former is only 1.67% larger than the latter.With the same reinforcement ratio,the cracking load of the reinforced alkali-activated sea sand concrete beams is larger than the cracking load of the BFRP reinforced alkali-activated sea sand concrete beams.And the reinforcement ratio of BFRP reinforced alkali-activated sea sand concrete beam should not be too large.(2)This paper uses the fractal theory analyze the cracks of the BFRP reinforced alkali-activated sea sand concrete beams.The results show that the cracks of the test beam are self-similarity.It is feasible to use the fractal theory to describe the crack development of the test beam and its fractal dimension is between 0.9 and 1.1.The relationship between load grade and fractal dimension is discussed.The results show that there is a logarithmic growth relationship between the load grade and the fractal dimension,and the fractal dimension increases with the increase of the load.(3)The finite element simulation analysis of the flexural behavior of alkali-activated sea sand concrete beam with BFRP bars was carried out to verify its rationality.The results show that the finite element simulation results are not much different from the experimental results.The ABAQUS analysis software can accurately simulate the flexural behavior of alkali-activated sea sand concrete beam with BFRP bars.The simulation results and test results verify each other.And it can provide reference for engineering applications to provide reference for the design and application of this new structure of BFRP reinforced alkali-activated sea sand concrete beams.(4)The experimental data of the experimental study on flexural behavior of alkali-activated sea sand concrete beam with BFRP bars is modified to calculate the calculation formula of FRP reinforced concrete structure in China.The formula for calculating the crack width,deflection and the ultimate flexural capacity of BFRP reinforced alkali-activated sea sand concrete beams are obtained.The results show that the modified formula can calculate the crack width,deflection and the ultimate flexural capacity of BFRP reinforced alkali-activated sea sand concrete beams,which can provide reference for the BFRP reinforced alkali-activated sea sand concrete beam structure design.