The influence of relative humidity on structural and chemical changes during carbonation of hydraulic lime
Studies monitoring the carbonation of NHL3.5 hydraulic lime are described. Weight-gain measurements, focused ion beam imaging, X-ray diffraction, X-ray 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.
- OSTI ID:
- 21033060
- Journal Information:
- Cement and Concrete Research, Vol. 37, Issue 8; Other Information: DOI: 10.1016/j.cemconres.2007.05.002; PII: S0008-8846(07)00119-6; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0008-8846
- Country of Publication:
- United States
- Language:
- English
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