Significance of pre-existing cracks on nucleation of secondary ettringite in steam cured cement paste
✍ Scribed by Yan Fu; Ping Xie; Ping Gu; J.J. Beaudoin
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 664 KB
- Volume
- 24
- Category
- Article
- ISSN
- 0008-8846
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✦ Synopsis
Surface chemistry theories of crystal nucleation in pre-cracked material were examined. It was deduced that nucleation first occurs in cracks satisfying a minimum free energy condition. This concept was used to explain deterioration accompanying secondary ettringite formation in steam cured precast concrete. The effect of pre-existing crack size on crack propagation and expansion due to secondary ettringite formation is also discussed in terms of the Griffith fracture theory. The test results support the argument that steam cured Portland cement paste containing pre-existing cracks, especially those systems undergoing severe drying, is subject to large expansion. SEM_/EDXA verified the presence of highly concentrated ettringite crystals in the cracks.