TY - JOUR
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
Y1 - 2007
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
M3 - Article
VL - 37
SP - 1233
EP - 1240
JO - Cement and Concrete Research
JF - Cement and Concrete Research
IS - 8
ER -