Research On Rheological And Electrical Properties And Mechanical Properties Of Cement-based Materials

With the wide application of high-performance concrete,people have higher requirements for workability.Studying the rheological properties of concrete can reveal the main factors affecting the workability more deeply.Resistivity method has shown strong adaptability in studying various properties of cement slurry.In this paper,various cement-based materials were tested for resistivity development,compressive strength,setting time,spread diameter and rheological parameters.Through experiments and data processing,the relationship between resistivity and rheological properties was achieved.The main research results are as follows:（1）For cement pastes with different water-cement ratios,the lower the water-cement ratio,the higher the resistivity after 24h,the higher the compressive strength at 28d,the earlier the setting time,the smaller the spread diameter,and the higher the rheological parameters.There is a quantitative mathematical relationship between rheological parameters and the water-cement ratio.Resistivity and shear stress are related by the slope of the logarithm of time,thereby realizing the use of resistivity and water-cement ratio to predict the early shear stress of cement paste.（2）Various tests were performed on the cement slurry with metakaolin content of 5%,10%,and 15%,and combined with the test results,the mixed slurry with 5%content performed better.Due to the secondary reaction of metakaolin and cement hydration product,(6（）₂,the resistivity rate development curve of the mixed slurry has an additional peak.There is a quantitative mathematical relationship between rheological parameters and metakaolin content.The resistivity and metakaolin content can be used to predict the early shear stress of mixed slurry.（3）Various tests were performed on the cement slurry with the polycarboxylate-type superplasticizer of 0.1%,0.15%,and 0.2%,and comprehensive data analysis showed that the slurry performed best when the content was 0.15%.There is a quantitative mathematical relationship between rheological parameters and the amount of water reducing agent.The resistivity and the amount of water reducing agent can be used to predict the early shear stress of the mixed slurry.（4）The COMSOL software was used to simulate the flow of cement slurry in a 90°elbow.The research results found that in actual engineering,the use of elbows should be avoided.If it must be used,stepped pressure pumping should be set up.And strengthen the bearing capacity of curved pipe fittings.Choose a suitable input pressure,and choose a higher water-cement ratio.