Sodium molybdate for concrete details

Sodium molybdate for concrete

Keywords
Concrete, sodium molybdate, rust inhibitor, retarder, plasticizer, reinforcing agent

Sodium molybdate Na2MoO4
CAS No. 7631-95-0

White rhombohedral crystals. Molybdenum trioxide can be produced by oxidizing and roasting molybdenum concentrate, leaching with liquid caustic soda to produce sodium molybdate solution, and then it can be obtained after suction filtration, concentration, cooling, centrifugation and drying.

Alias: Sodium molybdate dihydrate, Sodium molybdate, disodium molybdate

Character
White crystalline powder. 
pH of 5% aqueous solution is 9.0-10.0 at 25C.  
Relative density (d184) 3.28.  
The melting point is 687C.

Role in concrete
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 an ideal retarder for concrete.  Extend the plasticity of concrete from hours to days without compromising its strength.