Limitations of the Carbonate Extraction/UV Spectrophotometric Method for Determining Lignosulfonate-Based Admixtures in Hardened Concrete

    Volume 17, Issue 1 (June 1995)

    ISSN: 0149-6123

    CODEN: CCAOAD

    Page Count: 11


    Sanders, CI
    Research associate, research chemist, and technical specialist, W. R. Grace and Company, Cambridge, MA

    Nelson, NL
    Research associate, research chemist, and technical specialist, W. R. Grace and Company, Cambridge, MA

    Sadeghi, SS
    Research associate, research chemist, and technical specialist, W. R. Grace and Company, Cambridge, MA

    Abstract

    In 1963, a method for determining lignosulfonate addition rates in portland cements was reported (Wexler and Brako 1963). Over the years, this procedure has been adopted as the most common method for determining lignosulfonate-based admixtures in hardened concrete. The procedure involves extraction of lignosulfonate derivatives from pulverized concrete with an alkali-carbonate solution. The concentration of the extracted derivatives is then measured by comparing their ultraviolet (UV) spectra with those obtained from appropriate concrete standards.

    While widely applicable, we have encountered numerous limitations when using this method to investigate concrete performance problems. Among the factors that may affect the results of the carbonate extraction/UV spectrophotometric procedure are the source of lignosulfonate in the admixture, cement content, concrete maturity, and certain extractable constituents such as other admixtures, cement additives, organics from fly ash, and unknown constituents. In this paper, we will discuss the results of systematic studies that have been performed to determine how each of these variables can influence the accuracy of results obtained.


    Paper ID: CCA10335J

    DOI: 10.1520/CCA10335J

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    Author
    Title Limitations of the Carbonate Extraction/UV Spectrophotometric Method for Determining Lignosulfonate-Based Admixtures in Hardened Concrete
    Symposium , 0000-00-00
    Committee C09