Research On Impermeability Of Underwater Non-dispersible Concrete In Saline Soil

There are large areas of saline soil in western China such as Xinjiang,Qinghai and Gansu.The salt content in the saline soil environment is very high,causing serious corrosion to underwater non-dispersive concrete.Therefore,improving the durability of concrete has great engineering significance.The impermeability of concrete is one of the important indicators to measure its durability.This paper mainly research the impermeability of underwater non-dispersible concrete in the erosion environment of saline soil.Based on the requirements of the State Grid Corporation's science projects,this paper designed the underwater non-dispersive concrete of three strength grades,then soak the concrete used the salt solution that simulate the saline soil environment,and research the impermeability of underwater non-dispersive concrete.The main conclusions are as follows:?1?The basic properties of underwater non-dispersive concrete are studied.The slag powder can significantly improve the fluidity of underwater non-dispersive concrete,and reduce the anti-dispersion of underwater non-dispersive concrete.At 120s,the slump of concrete mixed with slag powder can be 6.12%higher than the blank,and the expansion can be12.64%higher than the blank.However,the concrete with slag powder has lower anti-dispersion than the blank.After testing,the working performance and mechanical properties of the underwater non-dispersive concrete in this paper meet the requirements of the specification.?2?The impermeability of underwater non-dispersive concrete was studied.Cl^-dose not have a significant impact on the impermeability of concrete.SO₄^2-reduces the impermeability of underwater non-dispersible concrete.The chloride ion diffusion coefficient of underwater non-dispersible concrete in the chloride salt environment is almost within 5%of the concrete in fresh water,and there is no significant difference in microscopic morphology.The chloride ion diffusion coefficient of underwater non-dispersible concrete in the sulphate environment is 6%to 15%higher than that in fresh water at 360 days,and a large amount of ettringite crystals are formed in the concrete under sulfate environment.Increasing the strength grade of concrete can significantly enhance its impermeability.At 360d,the chloride diffusion coefficient of underwater non-dispersible concrete with different strength grades differs by12%³0%.Adding slag powder can reduce the chloride ion diffusion coefficient of concrete,reduce the number of ettringite crystals in concrete,and make the concrete more dense.?3?The ion concentration at different depths of underwater non-dispersive concrete was studied.Increasing the strength grade of underwater non-dispersive concrete can significantly enhance its ability to resist the penetration of erosive ions.At the same test depth,the higher the strength grade,the lower the eroded ion content of the concrete.The incorporation of slag powder enhances the ability of concrete to resist the penetration of erosive ions and enhances the impermeability of concrete.The content of ions in concrete with slag powder can be50.36%lower than that of the blank at the depth of 5 mm,and can be 61.54%lower than that of the blank at the depth of 30 mm.?4?The pore structure of underwater non-dispersive concrete was studied.Chloride salt has little effect on the pore structure of concrete.Sulfate will increase the number of harmful pores in concrete,and increase the porosity of concrete.Slag powder can improve the pore size distribution of concrete,reduce the number of harmful pores and reduce the porosity of concrete.Therefore,the incorporation of slag powder can improve the impermeability of underwater non-dispersive concrete.