The Influence of Relative Humidity on Structural and Chemical Changes During Carbonation of Hydraulic Lime

Studies monitoring carbonation of NHL3.5 hydraulic lime are described. Weight-gain measurements, focused ion beam imaging, X-ray diffraction/photoelectron spectroscopy, and Raman spectroscopy were used to monitor changes in structure and composition occurring in lime pastes after exposure to 100% carbon dioxide at relative humidities of 65 and 97%. Lime paste exposed to a relative humidity (R.H.) of 97% indicated a higher carbonation rate compared to paste exposed to 65% R.H. Surface analysis showed that the sample exposed to a relative humidity of 97% was completely carbonated. No calcium hydroxide was detected. A small amount of calcium hydroxide was, however, present at the surface of the sample exposed to 65% R.H. These observations suggest that high humidity results in the formation of a thin layer of crystalline calcium carbonate covering silicate and hydroxide phases. The actual mass increase of the sample also indicated that uncarbonated calcium hydroxide remained beneath the surface.

Availability:
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Supplemental Notes:
- Abstract reprinted with permission from Elsevier
Authors:
- El-Turki, A
- Ball, R J
- Allen, G C
Publication Date: 2007-8

Language

English

Media Info

Media Type: Print
Features: Figures; Photos; References; Tables;
Pagination: pp 1233-1240
Serial:
- Cement and Concrete Research
- Volume: 37
- Issue Number: 8
- Publisher: Elsevier
- ISSN: 0008-8846
- Serial URL: http://www.sciencedirect.com/science/journal/00088846

Subject/Index Terms

TRT Terms: Carbonation; Cement additives; Cement mortars; Concrete structures; Moisture content; Structural deterioration and defects
Uncontrolled Terms: Hydraulic lime mortars; Relative humidity
Subject Areas: Highways; Materials; I32: Concrete;

Filing Info

Accession Number: 01077063
Record Type: Publication
Files: TRIS
Created Date: Sep 28 2007 8:02AM