The influence of relative humidity on structural and chemical changes during carbonation of hydraulic lime

A El-Turki; Richard J Ball; G C Allen

doi:10.1016/j.cemconres.2007.05.002

The influence of relative humidity on structural and chemical changes during carbonation of hydraulic lime

A El-Turki, Richard J Ball, G C Allen

Department of Architecture & Civil Engineering

Research output: Contribution to journal › Article › peer-review

57 Citations (Scopus)

Abstract

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.

Original language	English
Pages (from-to)	1233-1240
Number of pages	8
Journal	Cement and Concrete Research
Volume	37
Issue number	8
DOIs	https://doi.org/10.1016/j.cemconres.2007.05.002
Publication status	Published - 2007

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10.1016/j.cemconres.2007.05.002

http://dx.doi.org/10.1016/j.cemconres.2007.05.002

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title = "The influence of relative humidity on structural and chemical changes during carbonation of hydraulic lime",

abstract = "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.",

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T1 - The influence of relative humidity on structural and chemical changes during carbonation of hydraulic lime

AU - El-Turki, A

AU - Ball, Richard J

AU - Allen, G C

PY - 2007

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N2 - 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.

AB - 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.

UR - http://dx.doi.org/10.1016/j.cemconres.2007.05.002

U2 - 10.1016/j.cemconres.2007.05.002

DO - 10.1016/j.cemconres.2007.05.002

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