Impact of triethanolamine on the sulfate balance of Portland cements with mixed sulfate carriers

Abstract

The differences between the hydration of Portland cements with single and with mixed sulfate carriers in the presence of triethanolamine (TEA) were investigated, and possible mechanisms were proposed. Without TEA, cements with different types of sulfate carriers (gypsum, hemihydrate, anhydrite, and mixture of these) have a comparable hydration process at the same molar amount of calcium sulfate. At a TEA dosage of 0.5 wt.-%, the sample with a mixture of three sulfate carriers shows substantially stronger retardation of the C 3 S * 1 hydration than the cements with only one of these sulfate carriers, which is likely caused by the rapid formation of ettringite and the fast depletion of all sulfate carriers. These effects indicate that TEA influences the balance of sulfate carriers with aluminate-containing clinker phases. On the one hand, TEA can disturb the original sulfate balance due to the accelerated dissolution of aluminate-containing clinker phases, especially C 4 AF. On the other hand, these effects are closely related to the types and amounts of the sulfate carriers in the cement. A higher amount of sulfate carriers can minimize the TEA-related retardation of the C 3 S hydration and hemihydrate shows the strongest Accepted ArticleThis article is protected by copyright. All rights reserved impact at the same calcium sulfate quantity.

Working mechanism of calcium nitrate as an accelerator for Portland cement hydration

“…Nicoleau 26 argues that calcium salts allow the homogenous nucleation of C–S–H by increasing the availability of calcium in solution, and that this enhanced nucleation is responsible for the acceleration of alite hydration. In recent years, it has been regularly discussed that the onset of fast alite hydration in OPCs is retarded by aluminum in the pore solution 27–33 . Consequently, if Ca(NO 3 ) 2 , by altering the C 3 A hydration, reduces [Al] in the initial pore solution composition, this might be an aspect of alite hydration acceleration by Ca(NO 3 ) 2 that has not yet been fully considered.…”

“…In recent years, it has been regularly discussed that the onset of fast alite hydration in OPCs is retarded by aluminum in the pore solution. [27][28][29][30][31][32][33] Consequently, if Ca(NO 3 ) 2 , by altering the C 3 A hydration, reduces [Al] in the initial pore solution composition, this might be an aspect of alite hydration acceleration by Ca(NO 3 ) 2 that has not yet been fully considered.…”

Synergistic effect of aluminum sulfate and triethanolamine on the hydration of metakaolin blended cement

“…Many researchers found that TEA can enhance early strength at a low dosage of 0.01-0.05% (mass ratio of TEA to cement), while it retards the setting and sacrificed strength at a high dosage of 0.1% [18]. However, it again has a strong accelerating effect on the setting of cementitious materials [19,20] with the further increased TEA dosage. Zhang et al [21] showed that TEA modified the morphology of portlandite through the complexation with Ca 2+ , thereby reducing the porosity and enhancing the early strength.…”

Influence of the availability of calcium on the hydration of tricalcium aluminate (C3A) in seawater‐mixed C3A–gypsum system

“…[16][17][18] These properties of fresh cement paste and concrete are highly related to the aluminate phase in the cement clinkers, that is, tricalcium aluminate (C 3 A). 19,20 In fact, the hydration of C 3 A in cement clinkers could be affected by other phases of cement clinkers. For example, in the case of undersulfated systems, the C 3 A reaction occurred before the alite one, thus there was no obvious effect of alite on the C 3 A-gypsum reaction.…”

“…It has been reported that SW can accelerate cement hydration, 9–14 shorten the setting time 11,15 and decrease the workability 16–18 . These properties of fresh cement paste and concrete are highly related to the aluminate phase in the cement clinkers, that is, tricalcium aluminate (C 3 A) 19,20 . In fact, the hydration of C 3 A in cement clinkers could be affected by other phases of cement clinkers.…”