How to achieve anti-chloride ion and anti-rust for reinforced concrete in marine engineering?
Keywords
Concrete, rust inhibitor, sodium molybdate, sodium monofluorophosphate, triethanolamine, triisopropanolamine
Seawater contains chloride ions, so it is very important to take anti-corrosion methods for reinforced concrete in marine engineering.
1. In concrete, a large proportion of fly ash and mineral powder can be added to reduce the diffusion of chloride ions, thereby controlling the corrosion of chloride ions.
2. Adding rust inhibitors to concrete materials
Currently the main rust inhibitor materials:
Sodium monofluorophosphate MFP
Monofluorophosphate combines with calcium ions in concrete to form precipitated apatite, which covers the surface of steel bars to prevent oxygen from diffusing, inhibits cathodic reactions, and prevents corrosion of steel bars by aggressive media.
Sodium molybdate Na2MoO4
Sodium molybdate is a kind of weak oxidizing corrosion inhibitor. It starts to adsorb on the hydrated iron oxide film, so that the oxide film changes from anion selectivity to cation selectivity, passivates the metal surface, and forms a passivation film, which is effective The ground covering plays a good protective role on the surface of the material and prevents the occurrence of metal corrosion.
Adding a certain amount of sodium molybdate to cement can increase the plasticity and strength of concrete, and can be used as a good retarder for concrete materials. Extend the plasticity of concrete from hours to days without affecting its fastness.
Triethanolamine TEA
Triethanolamine can be used as a rust inhibitor in concrete. At the same time, triethanolamine and its salt solution can be used as an engineering admixture and early strength agent (0.1% of the total mass) in the cement clinker grinding process, which can improve the fluidity and packing density of cement. , but also improve the early strength and impermeability of concrete.
Triisopropanolamine TIPA
Triisopropanolamine improves the hydration degree of cement minerals by promoting the hydration and dispersibility of ferrite which is difficult to hydrate, thereby improving the early strength.
Organic rust inhibitors can usually diffuse in the pores of concrete in the form of gas-liquid two-phase. After the rust inhibitor reaches the surface of the steel bar, the functional groups of the rust inhibitor will be adsorbed on the surface of the steel bar to form a protective film. The organic rust inhibitor can be used as a blending material, or it can be directly coated on the concrete surface. Through the process of spontaneous migration and penetration, a film will be formed on the surface of the steel bar to realize the protection of the steel bar.
