INVESTIGATIONS OF DEVELOPMENT AND PRODUCTS OF ALKALI-SILICATE REACTION IN CONCRETE --PROCEEDINGS OF THE 7TH INTERNATIONAL CONFERENCE ON CONCRETE ALKALI-AGGREGATE REACTIONS, OTTAWA, CANADA, 1986

Development of alkali-silicate reaction was observed on test concrete samples, made of mixture of highly reactive silicate (chert) grains, described as opal and of inert reactive aggregate. First signs of alkali-silicate reaction on opal were observed with an alkali concentration in cement of 2.10% na2o equivalent. Expansive destructive effects are manifested under ideal conditions for reaction at an alkali concentration 3.42% na2o equivalent in cement. With higher alkali concentrations alkali-silicate reaction develops more rapidly. Reaction products are produced in different phases. Infra-red absorption spectrum of these products show some of the intermediate reactions which preceded the formation of alkali-silicate gel.(a) for the covering abstract of the conference see IRRD 811982.