Effect of amino alcohol admixtures on alkali-activated materials

Effect of amino alcohol admixtures on alkali-activated materials

Článek WoS

One of the most important technological problems associated with alkali-activated materials (AAM) is large shrinkage. Apossible solution to decrease the extensive drying shrinkage of these materials is the use of shrinkage-reducing admixtures(SRAs). The promising group of SRAs, from the perspective of using in AAMs, are amino alcohols. However, the efficiency ofreducing the drying shrinkage strongly depends on their chemical structure. Hence, the study is focused on the moleculararchitecture of amino alcohol surfactants and its relation to the affected properties of alkali-activated blast-furnace slag systems. Selected amino alcohols were tested in terms of the ability to reduce the surface tension of pore solution as well as to influencethe drying shrinkage, hydration mechanism and mechanical properties of AAMs. The study confirms that the length andbranching of the alkyl chain linked to the amino group play the key role in SRA efficiency. Amino alcohol surfactants with ahigh-carbon alkyl chain decreased dramatically both the surface tension and the drying shrinkage, but simultaneously negativelyaffected the process of alkali activation, resulting in a deterioration of the mechanical properties. Conversely, the addition of0.5w/ % of the surfactants with a low molecular weight, such as 2-(Methylamino)ethanol, showed a slight improvement of thecompressive strength after 7 d and 28 d, and at the same time reduced the drying shrinkage by 30 % compared to the referencesample.

One of the most important technological problems associated with alkali-activated materials (AAM) is large shrinkage. Apossible solution to decrease the extensive drying shrinkage of these materials is the use of shrinkage-reducing admixtures(SRAs). The promising group of SRAs, from the perspective of using in AAMs, are amino alcohols. However, the efficiency ofreducing the drying shrinkage strongly depends on their chemical structure. Hence, the study is focused on the moleculararchitecture of amino alcohol surfactants and its relation to the affected properties of alkali-activated blast-furnace slag systems. Selected amino alcohols were tested in terms of the ability to reduce the surface tension of pore solution as well as to influencethe drying shrinkage, hydration mechanism and mechanical properties of AAMs. The study confirms that the length andbranching of the alkyl chain linked to the amino group play the key role in SRA efficiency. Amino alcohol surfactants with ahigh-carbon alkyl chain decreased dramatically both the surface tension and the drying shrinkage, but simultaneously negativelyaffected the process of alkali activation, resulting in a deterioration of the mechanical properties. Conversely, the addition of0.5w/ % of the surfactants with a low molecular weight, such as 2-(Methylamino)ethanol, showed a slight improvement of thecompressive strength after 7 d and 28 d, and at the same time reduced the drying shrinkage by 30 % compared to the referencesample.

amino alcohols, admixture, drying shrinkage, alkali-activated materials

amino alcohols, admixture, drying shrinkage, alkali-activated materials

KALINA, L.; BÍLEK, V.; BARTONÍČKOVÁ, E.

2021

29.01.2020

1580-2949

Materiali in Tehnologije

54

3

Slovinská republika

349

353

5

http://mit.imt.si/izvodi/mit203/kalina.pdf

http://hdl.handle.net/