Triethanolamine cement hydration

Conduction calorimetric curves of Portland cement hydrated isothermally containing various quantities of triethanolamine are shown in Fig. 5.3 [8]. On initial contact with water each sample evolves heat (not shown in figure) that can be attributed to heat of wetting, hydration of free lime and reaction of C3 A with gypsum to form... 

Fig. 5.3 Conduction calorimetric curves of cement hydrated in the presence of triethanolamine (Ramachandran).

One of the limitations to the wider use of calcium chloride in reinforced concrete is that, if present in larger amounts, it promotes corrosion of the reinforcement unless suitable precautions are taken. The use of calcium chloride is banned in many countries. There is, hence, a continuing attempt to find an alternative to calcium chloride, one equally effective and economical, but without its limitations. A number of organic and inorganic compoimds including aluminates, sulfates, formates, thiosulfates, nitrates, silicates, alkali hydroxides, carbonates, halides, nitrites, calcium salts of acetic acid, propionic acid, butyric acid, oxalic acid and lactic acid, urea, glyoxal, triethanolamine, and formaldehyde have been suggested. However, practical experience and research on these admixtures are limited. The effect of these compounds on the hydration of individual cement compoimds and cement has been widely studied by thermal analysis techniques. 

Figure 15. DTA estimation of lime in cement pastes hydrated with triethanolamine.

The addition of fully hydrated CAC to hydrating CAC systems can reduce setting times significantly. This behavior, also observed in portland cement systems, can be attributed to a nucleation mechanism.Set acceleration can also occur with the addition of dilute solutions of sodium, potassium and lithium salts, or organic bases, e.g., triethanolamine. 

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