Title:
Expansion of MgO in Cement Pastes Measured by Different Methods
Author(s):
Michelle R. Nokken
Publication:
Materials Journal
Volume:
107
Issue:
1
Appears on pages(s):
80-84
Keywords:
brucite; limewater; periclase.
DOI:
10.14359/51663469
Date:
1/1/2010
Abstract:
In North America, expansion of periclase (MgO) is assessed with ASTM C151. Due to the potential safety hazard, and the fact that not all testing laboratories have access to the equipment, a test method using storage of paste bars in limewater at 80°C (176°F) was assessed. Cement paste mixtures containing 0, 2, 4, 6, and 8% hard-burnt periclase were investigated. The Le Chatelier test and expansion of paste prisms exposed to 3-hour boiling, 80°C (176°F), and the standard ASTM C151 method were compared. Le Chatelier test results were highly variable and not suitable to determine potential brucite expansion. Both the 3-hour boiling and the 80°C (176°F) method were found to be highly correlated to the ASTM C151 results, but resulted in 2% and 10% of the total autoclave expansions, respectively. X-ray diffraction (XRD) results showed that the more severe the exposure, the greater the conversion of periclase to brucite.