Study On The Mechanism Of Hydration Resistance Of Cement Hydration Products

As the state of marine resources and coastal security more and more attention,a large number of marine engineering construction,concrete as the basic structure of marine engineering materials,its stability is very important,different from the land environment,there are a lot of ions in the sea,some of the concrete In this paper,three kinds of main erosive ions: Cl-,Mg²⁺and SO₄^2-in seawater are studied in this paper according to their different erosive mechanisms.Through the study of the relationship between C₃ A,AFm and AFt,and the transformation conditions,the thermodynamic theoretical analysis was carried out,and the theoretical basis of material transformation was put forward.And then experimentally verified,including calcination through high-temperature furnace made of high purity C₃ A,the transformation experiment,and the samples were XRD and SEM microscopic analysis,The results show that C₃ A and AFm can be converted into Fridel's salt in the presence of Cl-,and thermodynamically analyzed AFt can not react with Cl-to produce Fridel's salt or trichloroaluminate,but the thermodynamics The existence of Fridel's salt is absent in the XRD patterns.The possible reasons are that the ettringite transformation process is not complete,and there is a certain amount of C₃ A or AFm,or there is a dynamic equilibrium between AFt and AFm.Can be transformed into each other.For the Mg²⁺ and SO₄^2-,cement mortar specimens were immersed in the etching experiments at different ages in the etching solution.Then,the mechanical properties of the mortar were tested?bending and compressing?The microstructures of the samples were analyzed by XRD,SEM and BET.The erosion mechanism of different corrosive ions for different cement concrete was analyzed microscopically and macroscopically.The results show that the cement is in poor performance when faced with Mg²⁺and SO₄^2-.The Slag Cement has poor resistance to Mg²⁺ and the anti-SO₄^2-erosion ability is better than that of theOrdosilica Cement.Compared with the slag Cement has better resistance to Mg²⁺and SO₄^2-erosion;sulphoaluminate-based cement due to its unique hydration characteristics,in the Mg²⁺and SO₄^2-erosion environment,the strength to maintain good,anti-erosion ability is relatively better,since With sulphoaluminate type A and self-sulphoaluminate B-type cement from the micro and macroscopic contrast is not very different.Vertical comparison of several types of cement anti-erosion ability,since the Self-formulated type A = Self-formulated type B > super-sulfate cement > slag cement > general silicon cement.