Effect Of LC~3 Cement-based Materials On Chloride Ion Attack And Its Influencing Factors

Solving the shortage of natural raw materials and energy in construction and reducing greenhouse gas emissions have always been hot issues explored by the construction industry.In recent years,LC3 cement has attracted the attention of academia and engineering as a new material with energy saving,emission reduction and good economic benefits.In addition,after the seawater / sea sand began to be utilized,its durability,especially the impact of chloride ions on water concrete,became a hot issue.Therefore,this article systematically and thoroughly studied the material properties of LC3 cement-based composite materials through the hydration heat test,compressive strength,chloride ion natural erosion test,chloride ion rapid erosion test and chloride ion titration test,combined with micro-testing technology and theoretical analysis.The resistance of LC3 cement to external chloride ion attack and the law of interaction with the internal chloride ion of the matrix were discussed.The main research results are as follows:(1)The research on the basic properties of LC3 cement samples with different cement clinker contents,different clay and limestone ratios and different gypsum contents shows that: Although the compressive strength of LC3 cement is slightly lower than that of portland cement at 1d and 3d,it can reach or even exceed that of portland cement at 7d and 28 d.When the amount of cement clinker is 45%-65%,the compressive strength increases as the amount of cement clinker.The larger the clay to limestone ratio,the higher the compressive strength.Reducing the amount of gypsum will reduce the compressive strength of LC3 cement in the early stage,but it has little effect on the compressive strength of 28 d.Calcined clay and limestone will continuously consume calcium hydroxide for secondary hydration reaction.The addition of calcined clay will increase the production of 3d-28 d ettringite.(2)By analyzing the resistance of LC3 cement samples with different amounts of cement clinker,different proportions of clay and limestone,and different amounts of gypsum to external chloride ion erosion,we can know: LC3 cement is far more resistant to chloride attack than portland cement.The resistance of LC3 cement to external chloride ions and the ability to bind external chloride ions decreases with the increase of cement clinker and gypsum,and increases with the of clay and limestone.(3)The basic properties of seawater / sea sand LC3 cement samples with different cement clinker contents,different clay and limestone ratios,and different gypsum contents after adding chloride ions are studied: For seawater / sea sand LC3 cement,increasing the amount of cement clinker can increase the compressive strength.Increasing the proportion of clay and limestone is conducive to the improvement of early compressive strength.The change of gypsum content has little effect on compressive strength.The binding ability of LC3 cement to chloride ions weakens with the increase of cement clinker content,increases with the increase of the proportion of clay and limestone,and increases with the decrease of gypsum content.The addition of chloride ion can accelerate the secondary hydration time of the early calcined clay and limestone,but it will eventually reduce the reaction degree of the calcined clay and limestone.The above research results not only further improve and improve the relevant theories and levels of the LC3 cement system,but also provide a solid technical guarantee for the application of LC3 cement in marine environment construction projects and the utilization of seawater / sea sand.It promotes the construction of a maritime power,the Belt and Road,and the GuangdongHong Kong-Macao Greater Bay Area into a green,sustainable and healthy stage of development.It also provides technical reference for coastal areas rich in marine resources.Therefore,it has broad engineering application prospects,great practical significance and social and economic value.