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The influence of alkali-free and alkaline shotcrete accelerators within cement systems
Influence of the temperature on the sulfate attack mechanisms and damage
AbstractThe resistance to sulfate attack of mixtures accelerated with alkali-free and alkaline accelerators was found to be mainly influenced by the Al3+ and SO42− added via the admixtures. Microstructural observations showed decalcification and disintegration of the CSH gel, which acted as an additional Ca2+ supplier as compared to the CH for ettringite formation. The CSH decalcification was mainly observed with a homogeneous distribution of the alkali-free admixture. The disintegration of the CSH gel increased the porosity and allowed more sulfate solution to penetrate into the specimens. This process promoted the swelling of the specimens and directly contributed to the expansion, explaining the lack of a direct relationship between the ettringite formation and the expansion. Moreover, the CSH gel disintegration, typical for MgSO4 attack, also occurred with Na2SO4 solutions and depending on the aluminate–sulfate distribution and the extent of the CSH gel disintegration, different damage types were detected. At higher temperatures (65 °C) the damage was mainly controlled by the growth, the rearrangement and the thermal stability of ettringite.
The influence of alkali-free and alkaline shotcrete accelerators within cement systems
Influence of the temperature on the sulfate attack mechanisms and damage
AbstractThe resistance to sulfate attack of mixtures accelerated with alkali-free and alkaline accelerators was found to be mainly influenced by the Al3+ and SO42− added via the admixtures. Microstructural observations showed decalcification and disintegration of the CSH gel, which acted as an additional Ca2+ supplier as compared to the CH for ettringite formation. The CSH decalcification was mainly observed with a homogeneous distribution of the alkali-free admixture. The disintegration of the CSH gel increased the porosity and allowed more sulfate solution to penetrate into the specimens. This process promoted the swelling of the specimens and directly contributed to the expansion, explaining the lack of a direct relationship between the ettringite formation and the expansion. Moreover, the CSH gel disintegration, typical for MgSO4 attack, also occurred with Na2SO4 solutions and depending on the aluminate–sulfate distribution and the extent of the CSH gel disintegration, different damage types were detected. At higher temperatures (65 °C) the damage was mainly controlled by the growth, the rearrangement and the thermal stability of ettringite.
The influence of alkali-free and alkaline shotcrete accelerators within cement systems
Influence of the temperature on the sulfate attack mechanisms and damage
Paglia, C (author) / Wombacher, F (author) / Böhni, H (author)
Cement and Concrete Research ; 33 ; 387-395
2002-08-13
9 pages
Article (Journal)
Electronic Resource
English
The influence of alkali-free and alkaline shotcrete accelerators within cement systems
| British Library Online Contents | 2001
The influence of alkali-free and alkaline shotcrete accelerators within cement systems
| British Library Online Contents | 2003
| British Library Online Contents | 2004