STP205

    The Alkali-Aggregate Phase of Chemical Reactivity in Concrete—Part II: Deleterious Reactions Observed in Field Concrete Structures

    Published: Jan 1958


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    Abstract

    Part I of this series2 included several chemical experiments designed to explain and illustrate the reactions between the alkali hydroxides and several types of reactive silica. As a result of these reactions a number of conclusions can be formed; however, the following are the more directly related to the second part of this series.

    1. The reaction between alkali and reactive aggregate is greatly aided by the regeneration of the alkali by lime.

    2. Reactivity between comparatively low-alkali concentrations and certain types of reactive aggregate will proceed under conditions favorable to the reaction.

    3. From a controlled set of mortar bars that were allowed to react for a period of 46 months, analysis showed that the total acid soluble silica in each bar varied directly with the alkali content and the total expansion.

    4. By the addition of controlled amounts of certain types of finely divided silica, it is possible to reduce or even eliminate expansion in concrete due to alkali aggregate activity.


    Author Information:

    Hester, JA
    Bureau of Materials and Tests, Montgomery, Ala.

    Smith 1, OF
    Bureau of Materials and Tests, Montgomery, Ala.


    Paper ID: STP39462S

    Committee/Subcommittee: C01.32

    DOI: 10.1520/STP39462S


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