Title:
Monitoring pH in BCSA Cement
Author(s):
Kienzle
Publication:
Web Session
Volume:
ws_S23_Kienzle.pdf
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
4/2/2023
Abstract:
This research seeks to understand how the alkalinity of the pore solution in belitic calcium sulfoaluminate (BCSA) cement changes during hydration. BCSA is an emerging form of rapid-set cement. The ability to achieve high early strength and the potential for increased sustainability makes it a desirable alternative to traditional portland cement. Despite its many potential benefits, there are lingering questions about the corrosion performance of BCSA concrete. In portland cement, the initiation of hydration causes it to rapidly reach and remain at high alkalinity. High alkalinity enables reinforcing steel to develop a stable passive film, which protects the steel from corrosion. This passivation usually occurs at a pH above about 11.5. It is known that BCSA cements have lower alkalinity than portland cement, but most authors suggest it is sufficient to passivate the steel. Laboratory tests of steel-reinforced BCSA concrete show initiation of corrosion at a very early age, but this behavior has not been observed in the field. Our hypothesis is that the steel does not passivate until a later age in BCSA cement due to differences in the hydration chemistry. This research will monitor the pH of the BCSA cement pore solution using ex-situ leaching tests and dilute slurry analysis to gain insight into the time scale of steel passivation in BCSA cement concrete. The results of these tests will advance knowledge on the corrosion performance of BCSA concrete, provide insight into discrepancies between BCSA concrete field conditions and laboratory corrosion tests, and help better design laboratory corrosion tests for BCSA and other alternative cements.