Study On Mechanical Properties Of Fiber Reinforced Concret Confined By Reinforced Mesh With Low Modulus And Strong Joints

Cement concrete pavement has high stiffness,strong diffusion load capacity,and good stability.It is one of the main structural forms of highway pavement.However,cement concrete has high brittleness,poor adaptability to deformation and poor crack resistance,fatigue cracking resistance and rapid crack propagation resistance.Weak,especially when uneven support,voiding,uneven subsidence of the roadbed occurs between layers,the road slab is prone to early breakage under heavy load,and the design life of the cement concrete pavement is difficult to guarantee.In view of the shortcomings of cement concrete in terms of crack resistance,this paper based on the principle of fiber crack resistance and toughening and the principle of crack resistance of composite structure of reinforced materials,starting from two angles of material and structure,an exploratory proposed crack-resistant concrete pavement structure New concept-low modulus and strong node reinforced mesh constrained fiber concrete pavement structure.In this paper,the research method of the combination of theoretical analysis,experimental research and finite element numerical simulation is used to analyze the crack resistance mechanism of the new pavement structure,and on the basis of testing the mechanical parameters of the reinforced mesh material and steel fiber concrete The experimental research on the bending crack resistance of steel fiber reinforced concrete beams constrained by low-modulus and strong-node reinforced meshes was established.At the same time,the pavement structure model was established using ABAQUS finite element software.The effect of cracked concrete pavement in improving crack resistance.The main research contents and conclusions are as follows:（1）The crack resistance and strengthening mechanism of steel fiber reinforced concrete pavement constrained by low modulus and strong node reinforced mesh are analyzed.On the one hand,using the cracking and toughening effect of steel fibers to enhance the toughness and crack resistance of concrete,so that it can still have a certain ability to work with cracks after cracking;on the other hand,the use of low modulus strong node reinforcement mesh Restraining effect on the subsequent expansion of existing cracks in the steel fiber concrete,which significantly reduces the stress intensity factor at the crack tip,enhances the crack’s ability to stably propagate,delays the penetration rate of cracks,inhibits broken plates,and improves the cracked steel fiber concrete The ability of the road surface to withstand heavy loads.（2）The effect of low modulus reinforced mesh on the bending crack resistance and adaptability of steel fiber reinforced concrete beam specimens was studied,and co MPared with ordinary steel fiber reinforced concrete specimens without reinforcement meshes.The test results show that the low modulus reinforced mesh has little effect on the cracking load of the steel fiber concrete specimen,but when the steel fiber concrete is cracked,the crack resistance enhancement effect of the low modulus reinforced mesh is prominent,and the concrete’s ability to adapt to deformation is significantly enhanced.After the test piece cracked,the load-deflection curve of the ordinary steel fiber reinforced concrete test piece showed an obvious rapid downward trend with the increase of deflection,and it could not continue to withstand higher levels of load.The load-deflection curve decreases only slightly after cracking,and then the curve will continue to increase as the deflection increases,and will even exceed the cracking load,and the crack resistance will be greatly improved.And with the increase of deflection,its bearing capacity can be kept basically stable in a longer range of deflection deformation,and the ductility of the structure is greatly improved,giving the concrete a good ability to adapt to deformation and load after cracking.（3）The effect of different low-modulus reinforced net laying heights on the bearing capacity and bending toughness of steel fiber reinforced concrete trabecular specimens was studied,and co MPared with ordinary steel fiber reinforced concrete specimens without reinforced meshes.The test results show that the different heights of the reinforced mesh laying have different effects on the lifting capacity and toughness of the concrete specimen.The lower the laying position,the better the overall effect.When the height of the reinforced mesh is 1cm away from the bottom of the test piece,the bearing capacity,bending toughness index and bending toughness factor are significantly improved co MPared to the ordinary steel fiber reinforced concrete test piece without reinforced mesh:under the same deflection,the cracking deflection is 1mm～2mm The increase of the bearing capacity corresponding is 53%～935%;co MPared with the same crack opening displacement,the bearing capacity increase range is 160%～353%when the crack opening displacement is 1mm～2mm;the bending toughness index₅ has increased From 23%to 28%,the bending toughness index₁₀ increased by 114%to 142%,and the bending toughness factor increased by 21%to 28%.（4）The pavement structure model was established by ABAQUS finite element software,and the effects of changes in the elastic modulus and cross-sectional area of the low-modulus reinforced mesh on the bearing capacity and crack propagation after pavement cracking were explored.The results of the study indicate that after the cracking of the concrete pavement floor,the low modulus reinforced mesh begins to function and significantly inhibits the subsequent further expansion of the crack.And the higher the crack development height,the greater the modulus and cross-sectional area of the reinforced mesh,the more obvious the effect of inhibiting crack propagation;the low modulus reinforced mesh modulus is 30GPa,the mesh size of the reinforced mesh is 4cm×4cm,When the cross-sectional area of a single bar is 100mm2（5mm×20mm）,taking the crack of a pavement that has been cracked 8cm high as an example,the load required for the crack to expand again is about 20%higher than that of a steel fiber concrete pavement without a reinforced mesh.At 13cm height,the bearing capacity of the road slab is increased by about 47%.When the crack penetrates to the full thick Ness（24cm）of the steel fiber reinforced concrete pavement without reinforcement mesh,the crack of the steel fiber reinforced concrete pavement constrained by the low modulus reinforced mesh only extends to 17cm,and about 30%of the plate thick Ness is not penetrated by the crack It shows that the low modulus reinforced mesh can significantly inhibit the crack propagation of the pavement,thereby avoiding further water damage caused by the crack penetration and improving the service quality and service life of the pavement.