Influence Of Steel Fiber On Mechanical Properties Of Ultra-high Performance Concrete And Simulations Of Finite Element

With the rapid development of domestic economy,the performance of traditional reinforced concrete materials has been far from meeting the needs of The Times.Therefore,it is necessary to popularize a new material which can not only greatly improve the strength and durability,but also meet the requirements of green environmental protection.Based on the above reasons,the research of Ultra-High Performance Concrete(UHPC)is carried out in this paper.This paper mainly does the following research: according to the experience and the actual needs of the formulation of the material mix ratio,according to the corresponding steps,through the mixer,dog bone mold and other equipment to make the test piece;The influence of steel fiber on the mechanical properties of UHPC was analyzed according to the compression,flexural,tensile strength and tensile stressstrain curves measured by the instrument.The tensile and compressive tests of straight fiber single-doped UHPC specimens were simulated by ABAQUS finite element software,and the simulation results were compared with laboratory test results.Made UHPC products which can be directly used for promotion;According to the advantages of rich copper and lithium tailings resources in Jiangxi,the idea of using copper tailings and lithium slag as UHPC admixture was put forward.The results show that:(1)When the fiber is mixed alone,the compressive strength of the specimen with8 mm short coarse fiber is the highest,and the strength reaches 162.8MPa;The endhook fiber has no obvious effect on the compressive strength of the specimen.When the fiber is mixed,the maximum compressive strength of the specimen reaches163.9MPa,which is slightly higher than that of the single doping.(2)The flexural strength of the specimens in each group is similar,and the flexural strength of the specimens is slightly higher when the fibers are mixed alone.(3)The tensile strength of the specimen with 16 mm long straight fiber is the highest,reaching 12.68MPa;The end-hook fiber can obviously improve the tensile strength of the test block.(4)In the tensile test,the initial stress and strain of the specimen show a linear relationship;The strain hardening stage approximates a straight line.The ultimate elastic tensile strength is approximately 70% of the tensile strength.(5)The tensile and compressive tests of UHPC specimens were simulated by finite element software ABAQUS.The results of tensile simulation show that,in the elastic stage,the simulated and experimental results are similar,and the curve difference between them becomes larger with the further increase of strain.It was found in the compression simulation that the simulated value of compressive strength was close to the measured value,and the error was within 5%,which verified the accuracy of the simulation.(6)Two kinds of UHPC products(UHPC board,UHPC decoration)can be directly used for promotion.In order to solve the problems such as cracking and fiber protrusion during production,the method of spraying the surface with sprayer and laying UHPC layer was adopted respectively.(7)In view of the rich copper and lithium ore resources in Jiangxi Province and the problem of large amount of tailings accumulation,it is proposed that copper tailings and lithium slag should be applied to UHPC.The low price of tailings can reduce the cost of UHPC,which is conducive to the promotion and application of UHPC and the realization of the green development of UHPC.