Page 172 - Handbook of Thermal Analysis of Construction Materials

Section 2.0 - Accelerators 155

When added to cement, triethanolamine decreases its strength at all
ages. Figure 5 shows the strength development in cement pastes containing
0, 0.1, 0.25, 0.35, 0.5, and 1% triethanolamine. [46] Strength decreases as the
amount of triethanolamine is increased.
Amine salts are used in combination with other chemicals. Kuroda,
et al., [47] tested the effect of a formulation containing calcium nitrite,
calcium rhodonate, and TEA. Both initial and final setting times were
accelerated by this admixture combination at 5 and 20°C. The compressive
strength of concrete also increased at these temperatures.

Figure 5. Compressive strengths of cement pastes containing triethanolamine.

Although it has been shown that TEA decreases the strength of
portland cement systems, it acts differently with blast furnace cements. In
a mortar containing 30% portland cement and 70% slag, at 7 days with 0.5%
TEA, the strength increased by about 40%. The total porosity of the paste
was lower in the presence of TEA. The TEA promoted acceleration of
hydration by increasing the rate of reaction of gypsum with slag in the
presence of lime. [48]