Formation and stability of 3CaO·CaCl 2·12H 2O

Abstract

Formation of 3CaO·CaCl 2·12H 2O, which is a very unstable complex salt, in deteriorated concrete attacked by calcium chloride has been regarded as a main cause for the deterioration of cement concrete. In this study, a slurry from Ca(OH) 2–CaCl 2–H 2O system was examined under different conditions. X-ray diffraction (XRD) analysis indicates that 3CaO·CaCl 2·12H 2O cannot be detected in the original slurry, but is detected after acetone washing of the slurry. 3CaO·CaCl 2·12H 2O disappears when the acetone-washed sample is air-dried at 20°C and 20% relative humidity. Thus, cautions should be taken during the preparation of samples during the examination of calcium chloride attacked concrete.