Volume 22, Issue 2 (December 2000)

    Chemical and Petrographic Analyses and ASTM Test Procedures for the Study of Delayed Ettringite Formation

    CODEN: CCAOAD

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    Abstract

    Although many papers have been written on case studies of incidences of delayed ettringite formation (DEF), few demonstrate a careful study of the methods of analyses for the presence and concentration of the ettringite that has formed. In addition, possibly only one suggests a method to determine potential future development of destructive ettringite.

    Furthermore, there have been few papers that relate to methods of test for the potential that portland cements have in causing DEF, especially under conditions where curing temperatures are low.

    Our studies involving DEF have not only led us to develop improved analytical methods and tests, but have also demonstrated deficiencies in several techniques employed by other investigators, and formerly even by us. We have also studied the methods for their application as ASTM standards and procedures.

    This paper presents our analysis methods and test procedures. The following are discussed: 1. Petrographic procedures for DEF study, including discussions of their application, advantages, and deficiencies. 2. Scanning electron microscopy procedures for DEF identification and development, including sample preparation, backscatter and secondary electron procedures, elemental dot-mapping, and flashing materials (conductive coatings) for the sample surface. 3. Qualitative and quantitative analyses for ettringite, including X-ray diffraction (XRD) and differential thermal analysis (DTA). 4. Procedures for quantifying the potential degree of future DEF development in concrete, using accelerated hydration and DTA determination of any additional ettringite developed. 5. Quantitative procedures for determining the amount of ettringite formed, for example at 24 h, as influenced by component concentration changes (e.g., potassium sulfate versus gypsum).

    6. Use of ASTM methods for the evaluation of a cement for DEF potential.


    Author Information:

    Backus, LA
    Principal, consultant, affiliated consultant, senior petrographer, and senior chemists, Materials Science and Engineering Group, Wiss, Janney, Elstner Associates, Inc., Northbrook, IL

    Cechner, RA
    Principal, consultant, affiliated consultant, senior petrographer, and senior chemists, Materials Science and Engineering Group, Wiss, Janney, Elstner Associates, Inc., Northbrook, IL

    Martinek, RA
    Principal, consultant, affiliated consultant, senior petrographer, and senior chemists, Materials Science and Engineering Group, Wiss, Janney, Elstner Associates, Inc., Northbrook, IL

    Marusin, SL
    Principal, consultant, affiliated consultant, senior petrographer, and senior chemists, Materials Science and Engineering Group, Wiss, Janney, Elstner Associates, Inc., Northbrook, IL

    Hime, WG
    Principal, consultant, affiliated consultant, senior petrographer, and senior chemists, Materials Science and Engineering Group, Wiss, Janney, Elstner Associates, Inc., Northbrook, IL

    Jugovic, ZT
    Principal, consultant, affiliated consultant, senior petrographer, and senior chemists, Materials Science and Engineering Group, Wiss, Janney, Elstner Associates, Inc., Northbrook, IL


    Stock #: CCA10476J

    ISSN: 0149-6123

    DOI: 10.1520/CCA10476J

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    Author
    Title Chemical and Petrographic Analyses and ASTM Test Procedures for the Study of Delayed Ettringite Formation
    Symposium , 0000-00-00
    Committee C01