Research On Tensile Experiments Of High Toughness Resin Concrete With Steel Mesh

Due to unreasonable design and construction,inadequate maintenance,environmental erosion,effect,accidents and disasters,or the improvement of design standards and load levels,a large number of existing concrete bridges have the need for maintenance and reinforcement.As a key hub in traffic engineering,the reinforcement and transformation of bridges with closed traffic will greatly affect mass travel and vehicle transportation.Therefore,how to maintain and reinforce the existing bridge structures quickly under the low traffic affect has become an urgent problem.As a new type of composite material for rapid reinforcement of bridge structures,High Toughness Resin Concrete With Steel Mesh(HTRCS)has the advantages of fast curing,high strength,good crack resistance,strong bonding with concrete and steel,easy forming,low permeability,corrosion resistance and wear resistance.However,the research on materials is still in its infancy.At present,the research on mechanical properties of HTRCS generally adopts the method of meso-mechanics analysis.The research results mainly focus on the resin concrete matrix,but little on the mechanical properties of grid reinforced materials and their bonding properties.Supported by National Natural Science Fund(Grant No.51508474),the idea of directly obtaining the Macro-tensile properties of HTRCS by experiments is proposed in this dissertation,based on the assumption of homogeneity of materials.The main contents of this dissertation are as follows:(1)Based on the summary and analysis of the research status on HTRCS,combined with the ideas of material meso-mechanics,the shortcomings in current research are pointed out.At the research level of component materials,the mechanical properties of steel mesh and resin concrete,and their bonding properties should be supplemented;while at the research level of application,the bonding mechanism and failure mode of interface should be further studied,as well as the technology research.(2)HTRCS is mostly in the state of tension stress when applied in reinforcement,so the study on the tensile mechanical properties of materials is necessary.Take account the present situation of research on material and reinforcement application,it is pointed out that there are still many difficulties in predicting the tensile properties of composite materials by means of micro-mechanics analysis method.It is proposed that the average tensile mechanical properties of HTRCS can be measured directly by means of experimental study.In view of that HTRCS is a new composite material without standard test method,based on the literature research on the tensile test of engineering materials and theoretical analysis,especially on the configuration design,loading mode,measurement parameters and layout of the tensile test specimens,the tensile test method of HTRCS is established.Finally,the scientificalness and validity of the method are verified by experiments.(3)The basic mechanical properties of each component of HTRCS were obtained by experiments.The test results show that the ultimate tensile strength and ultimate tensile strain of a single corrugated steel wire are 1046 MPa and 63,300με.Before the peak load,the tensile stress-strain curves of single corrugated steel wire and braided steel mesh are almost linear.The tensile failure mode of braided mesh is that the steel wire breaks one by one,the ultimate tensile strength is 855 MPa,and the utilization rate of material strength is basically maintained at 80%.The average compressive strength of resin concrete cured 2 days is 85.7 MPa,which has reached 82% of the compressive strength of resin concrete cured 14 days.The corresponding tensile modulus of elasticity is 15.8 GPa,and the ultimate tensile strain is 633με.(4)According to the tensile test method proposed in this dissertation,the experiments of HTRCS specimens with single-layer and double-layer steel mesh is carried out.The loadelongation curve,cracking load and ultimate bearing capacity of composite materials were obtained,as well as the crack development behavior and failure mode of the specimens.On this basis,the stress-strain curves,modulus of elasticity,nominal cracking stress and ultimate tensile strength of the specimens are given.The experimental results show that the reinforcement ratio has little effect on the mechanical properties of HTRCS composites in elastic stage,but has a significant effect on the tensile behavior after cracking.Increasing the reinforcement ratio can effectively improve the bearing capacity of HTRCS composite plates,add the number of cracks,reduce the crack spacing,and provide greater ultimate elongation for composite materials.