Title:
Alkali-Silica Reaction; Part 2: The Effect of Chemical Additives
Author(s):
Monica Prezzi, Paulo J. M. Monteiro, and Garrison Sposito
Publication:
Materials Journal
Volume:
95
Issue:
1
Appears on pages(s):
3-10
Keywords:
alkali-silica reaction; chemical admixtures; chemical treatments;
concrete; mortar bars
DOI:
10.14359/346
Date:
1/1/1998
Abstract:
Many aggregates are susceptible to the alkali-silica reaction. As result of this reaction. mortar bars and concrete elements containing portland cement expand. In order to limit this expansion. chemical admixtures that interfere with the alkali-silica reaction can be introduced into the mixing water. The research discussed below describes how several of these chemical admixtures affect mortar-bar expansion. Mortar bars containing any of several chemical admixtures in the mixing water at initial molar concentrations of 1 or 2 were subjected to ASTM C 1260 tests. After the expansion test. samples were prepared from each of the mortar bars and examined in a scanning electron microscope with EDX capabilities. The following chloride salts and hydroxides were used: NaOH, KOH, LiOH NaCl, KCl, LiCl, CaCl2, MgCl2, and AlCl3. For a given initial molar concentration, the expansion test results indicated that the chloride salts with monovalent cations were the mast damaging. followed by those with divalent and trivalent cations. These results are in agreement with a theoretical model presented in a previous paper that explains the volume change behavior of the reaction product gels. This model attributes the swelling of the reaction product gel to double-layer repulsion forces.