Evaluation of Fly Ash for Controlling Alkali-Aggregate Reaction

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Title: Evaluation of Fly Ash for Controlling Alkali-Aggregate Reaction

Author(s): Shigeyoshi Nagataki, Hiroyuki Ohga, and Takeshi InqueI

Publication: Special Publication

Volume: 126

Issue:

Appears on pages(s): 955-972

Keywords: aggregates; alkali-silica reactions; fly ash; mortars; silicon dioxide; Materials Research

Date: 8/1/1991

Abstract:
Mortars using heat-resistant glass as aggregate were made using water-binder ratio of 50 percent, replacement ratio of fly ash from 0 to 30 percent by weight, and an alkali content of 1.2 percent weight of cement. Eight fly ashes were used as supplementary cementing materials. These mortars were cured at a temperature of 40 C and a relative humidity more than 95 percent, and the expansion of these mortars was measured. The concentration of soluble alkali ion in fly ash immersed in the solution containing sodium hydroxide and calcium hydroxide was also determined. Expansion of mortar depended on the type and the replacement ratio of fly ash. The concentration of soluble alkali ion in fly ash depended on the type of fly ash. Although expansion of mortar was independent of equivalent sodium oxide content in fly ash, it correlated with the concentration of soluble alkali ion in fly ash. By studying effects of physical/chemical properties and the amorphous silicon dioxide in fly ash, a method to evaluate the expansion of mortars containing fly ash was proposed based on amorphous silicon dioxide, the replacement ratio, and particle diameter of fly ash.