Experimental And Simulation Study On Crucial Factors Affecting Workability Of High Fluidity Concrete

In order to study the feasibility of high fluidity concrete in road maintenance,the influence test on workability of high fluidity concrete was carried out from the aspect of aggregate,and three key parameters,namely aggregate gradation,maximum particle size and sand ratio,were selected for experiment and simulation.Combined with the analysis of EDEM discrete element software,the application feasibility of EDEM discrete element software in construction practice is verified.Through actual test and simulation test,the working performance of high fluidity concrete is systematically analyzed.The main results are as follows:(1)The coarse aggregate gradation determined based on different distribution coefficients of Dinger-Funk equation,with the increase of distribution coefficient,the workability first increases and then decreases.When n=0.6,the workability is the best,with the slump expansion reaching 677.5mm and the J-ring expansion reaching 637.5mm.The experiment of compressive strength shows that in this study,the larger the value of distribution coefficient n is,the higher its strength is.In the case of high fluidity concrete that needs higher strength,the gradation with larger distribution coefficient should be adopted.(2)The maximum particle size has little influence on high fluidity concrete,so it is recommended to use high fluidity concrete with the maximum particle size of 19mm.However,the sand ratio has the greatest influence on the high fluidity concrete,showing the characteristics of mountain peak,and the performance is the best when the sand ratio is 34%.When the sand ratio is 30%,the phenomenon of collapse occurs,and when the sand ratio is 32%,the PA(through gap performance index)is as high as 107.5mm,which does not meet the construction requirements of high fluidity concrete.(3)The surface energy has the most significant influence on the simulation of high fluidity concrete.When the surface energy is greater than 30 J/m2,the particles basically do not flow.The surface energy of this paper is between 12-13 J/m2,which can be used as discrete element simulation parameters of high fluidity concrete.The impact coefficient has no significant correlation with the simulation of high fluidity concrete,and its influence on the results is not important.Different combinations of static friction coefficient and rolling friction coefficient also have certain influence on the test results.When good liquidity is needed,the parameters of both should be low.Under the calibrated contact parameters,the error between the simulation results and the actual results is within the allowable range,and the EDEM simulation results are more regular,with less external interference.