Title:
A Lithium-Based Admixture for ASR Control that Does Not Increase the Pore Solution pH
Author(s):
D. B. Stokes, H. H. Wang and S. Diamond
Publication:
Symposium Paper
Volume:
173
Issue:
Appears on pages(s):
855-868
Keywords:
Admixtures; alkali-silica reactions, lithium; lithium hydroxide
DOI:
10.14359/6216
Date:
9/1/1997
Abstract:
This paper describes the effect of a lithium nitrate-based admixture on the hydroxide ion concentration of the pore solution of hydrating pastes made from portland cement and water. No significant increase in the hydroxide ion concentration results from using this admixture in the mix, which is thus different than any published study with any other lithium compound. It has been reported that underdosing with lithium salts can increase the expansion due to ASR. The authors propose that this is mainly due to increases in hydroxide concentration observed with other lithium salts and therefore this admixture will not show such an effect. Mortar bar tests with the new admixture verify the hypothesis that the lithium nitrate-based admixture does not increase expansion at any dose. This is then a much safer admixture to use in the field with respect to risk from damaging ASR expansions. It is also much safer to handle than lithium hydroxide-based admixtures since solutions of lithium nitrate are much closer to neutral pH than lithium hydroxide solutions.