Triethanolamine is a colorless, transparent and viscous liquid at room temperature with a slight ammonia smell. It is hygroscopic and can absorb moisture and carbon dioxide in the air. Can be freely mixed with water and alcohol, soluble in chloroform, slightly soluble in benzene and ether. The pH of 0.1moI/L solution is 10.5. There is a danger of burning when exposed to high heat, open flame or contact with oxidants. Its aqueous solution is corrosive.
The mechanism of action of triethanolamine in cement:
In the cement hydration process, the generation, dissolution, coagulation, and hardening of products are intertwined. Because the cement hydration reaction gradually penetrates from the surface of the cement particles into the inner layer, it starts relatively quickly. Later, the colloidal film is produced on the surface of the cement particles, which hinders the penetration of water, so that the hydration becomes slower and slower.
Since triethanolamine has an emulsifying effect, when a triethanolamine solution is added to the concrete mixture, the triethanolamine molecules are adsorbed on the surface of the cement particles, forming a charged hydrophilic film, which hinders the agglomeration of the cement particles. It produces a suspension stabilizing effect. At the same time, when triethanolamine is dissolved in water, it reduces the surface tension of the solution, allowing the cement particles to better contact with water, accelerating the wetting and penetration of water into the cement particles, and strengthening the solid phase caused by hydration. The volume expansion causes the gelatinized layer of cement particles to continuously peel off, which strengthens the peptization dispersion effect and increases the dissolution of calcium oxide in the liquid phase. Therefore, triethanolamine plays a catalytic role in cement hydration.
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