Research On The Performance Of Cement-based Grouting Material With Fly Ash And Metakaolin

In the construction process of surface engineering and underground engineering,grouting technology has become a widely used technology.For engineering accidents that may occur in engineering,it can be effectively prevented by grouting technology.The choice of grouting material is of great significance for the grouting project.It is necessary to consider not only the geological conditions of the project,but also the economic benefits of the project.For the study of grouting materials,chemical grouting materials are widely studied mainly because of their good penetrating ability and controllable setting time,but most chemical materials have harm and high prices which is not conducive to its widespread use.More in-depth research on cement-based grouting materials is needed to carry out to effectively replace chemical grouting materials.Based on cement grouting materials,pozzolanic mineral admixtures of fly ash and metakaolin are used to conduct a series of tests including working performance tests and mechanical properties tests to determine the optimum amount of fly ash and metakaolin.Based on the optimum amount of fly ash and metakaolin,the mechanical properties of grouting materials and SEM electron microscopy were carried out under different environmental temperatures and different erosive environments.The main contents of this research are exhibited as follows:Firstly,A series of tests of working performance and mechanical performance including fluidity test,syneresis rate test,stone rate test,viscosity test,bending test and compression test were conducted in the case of mixing of fly ash and mixing of fly ash and metakaolin.Variations of each performance with content of fly ash and metakaolin were analyzed.It was found that fly ash content of 20%and metakaolin content of 4%were the optimum amount of grouting material.Secondly,on the basis of optimum amount of fly ash and metakaolin,the flexural strength test and compression test were conducted on the grouting materials after they were cured at different temperature of 20?,40? and 60? for 12h and 24h respectively.Orthogonal test method was used to analyze the effect of water-binder ratio,amount of activator and amount of water reducing agent on mechanical properties of grouting material.The analysis found that when the water-binder ratio is 0.40,the amount of the activator is 3%,the amount of the water reducing agent is 0.15%and the curing temperature is 60?,the grouting material can reach the optimum early strength.Thirdly,based on the optimum amount of fly ash and metakaolin,the flexural strength test and compression test were conducted on the grouting materials cured in solution sulfate solution and the composite solution of sodium sulfate and sodium chloride for 1 month,3 month and 5 month.The effects of water-binder ratio,the amount of activator and the amount of water reducer on the mechanical properties of grouting materials under different erosive environments were analyzed by orthogonal experiment.It is found that in the sodium sulphate solution,the strength of the grouting material tends to increase first and then decrease with the age of erosion,While in the composite solution of sodium sulfate and sodium chloride,it shows a trend of decreasing first and then increasing.Lastly,the degree of internal hydration reaction,the change of hydration reaction product and the morphology of internal space structure of grouting materials cured at different curing temperatures and different erosive environment were analyzed by SEM test.The microscopic mechanism was further analyzed by comparing the macroscopic mechanical properties.Figure 89 table 17 references 75...