Title:
Alkali Contribution From Limestone Aggregate to Pore Solution of Old Concrete
Author(s):
P. E. Grattan-Bellew
Publication:
Materials Journal
Volume:
91
Issue:
2
Appears on pages(s):
173-177
Keywords:
aggregates; alkali-silica reactions; calcium hydroxides; clays; illite; limestone; Materials Research
DOI:
10.14359/4570
Date:
3/1/1994
Abstract:
Laboratory tests showed that the alkali contents of the pore solutions in concrete cores taken from the Saunders Generating Station, Cornwall, Ontario, Canada, were higher than the estimated original value. The structure was built 30 years ago, using a marginally expansive, alkali-silica-reactive, argillaceous limestone. The excess alkali in the pore solution could possibly have been derived from the clay minerals in the limestone aggregate. This hypothesis was tested by making pastes of pulverized limestone, calcium hydroxide, and water, and storing them at 38 C for 90 days. Samples were removed periodically, and the amount of alkali in the calcium hydroxide solution was determined. The results of the determinations indicate that the amount of leachable alkali would probably be sufficient to account for the enhanced alkali contents in the pore solution in concrete cores from the structure.