Study On The Compressive Properties Of Modified Phosphogypsum-concrete Mesh Frame Composite Wall

Phosphogypsum is a solid waste residue produced by industrial production of phosphate fertilizer.Guizhou Province is a large province of phosphate mine.It owns two phosphate mines,namely,Fufu and Kaiyang,and discharges a large amount of phosphogypsum waste residue every year.At present,the main treatment method of phosphogypsum is stacking,which not only occupies a large amount of land,but also long-term stacking will pollute the soil and groundwater,therefore it is of great significance for the resource utilization of phosphogypsum.In this study,the industrial waste phosphogypsum was modified,and the phosphogypsum was applied as a building material to the phosphogypsum-concrete mesh composite wall,which provided an effective way to deal with the utilization of phosphogypsum.This paper first discusses the research status of the composite wall,and introduces the main contents and research significance of this paper.This topic firstly carried out compressive test of samples made of polyethylene fiber reinforced phosphogypsum.Using the principle of fiber reinforcement,a polyethylene fiber with a length of 3 mm was mixed into the phosphogypsum matrix,and a mixture of seven different types of polyethylene fibers was designed.A total of 42 cubes(100 mm × 100 mm× 100 mm)were fabricated.The test results show that the failure modes of polyethylene fiber reinforced phosphogypsum composites are mainly crust failure,X-shaped failure and local failure.The incorporation of polyethylene fiber can effectively control the expansion of cracks,improve the strength and ductility of materials And to prevent brittle damage.The compressive strength of composites increases first and then decreases with the increase of fiber content.When the fiber content is about 1.5%,the maximum strength(about 5.10 MPa)is reached,compared to the strength(about 3.51 MPa)of phosphogypsum without fiber,which is increased by 45.3%.By analyzing the stress-strain curve,the elastic modulus of the material is 1703.01 MPa and 2700.07 MPa respectively when the fiber content is 0% and 1.5%,which can provide reference for numerical simulation and practical engineering design.The finite element linear simulation of the fiber reinforced phosphogypsum-concrete mesh frame composite wall was carried out by ABAQUS software.It can be seen from the numerical simulation stress cloud diagram that the main bearing members of the wall are the middle column and the side column,and the filling material in the filling wall has a transmission sharing effect on the upper load.The presence of the filling material hinders the deformation of the wall and slows the vertical displacement of the floor beam when it is underpressure.Through the numerical simulation,the ultimate bearing capacity of the wall with no filling,phosphogypsum filling and fiber reinforced phosphogypsum filling under the uniform load is 600 kN,1080kN and 1247 kN,respectively,compared with the unfilled grid.The bearing capacity of the wall increased by 63.64% and 88.94%,respectively,and the filling material improved the mechanical properties of the wall significantly.The wall was 1/3-scaled,and three sets of 6-inch walls were designed and fabricated.The bearing capacity of the wall was tested by uniform loading.Under the vertical uniform load,the concrete beam in the grid wall mainly bears the tensile force caused by the bending moment and acts as the tie rod for the wall;the side column and the middle column bear most of the vertical load,and the filling material bears part of the vertical load..The test results show that the wall is destroyed first,and the whole wall loses its bearing capacity.When the fiber-filled phosphogypsum-filled wall is damaged,the phosphogypsum at the filling site has a wide and deep penetrating crack.After the column is destroyed,the phosphogypsum is detached from the grid;after the fiber-reinforced phosphogypsum filled the wall,the column is destroyed.Only a large number of micro cracks and deformations are generated,but the phosphogypsum falling off does not occur.Experimental studies have shown that the fiber-phosphorus gypsum-filled wall greatly improves the deformation performance of the wall and improves the ductility of the wall compared to the phosphogypsum wall.The test data analysis results show that the wall of the same section,the stress of the middle column is much larger than that of the side column and the filling material.Compared with the unfilled wall,the ultimate bearing capacity is increased by about 41%,and the maximum vertical of the floor beam.The displacement is reduced by about 45%.This data again confirms the role of filler material in improving wall bearing capacity and improving wall ductility.The comparison between the test results of the three walls and the results of the finite element analysis shows that the wall failure is consistent with the finite element stress cloud diagram,and the bearing capacity of the wall is relatively close,with an average error of less than 15%.It shows that the finite element results have higher precision and meet the requirements of construction engineering precision,which verifies the rationality of the finite element model.