Time Zero Value Based on S-Wave Reflection Loss Measurement for Early Age Shrinkage Monitoring of Cementitious Specimens Subjected to Sealed and Unsealed Curing Conditions

    Volume 40, Issue 3 (May 2012)

    ISSN: 0090-3973

    CODEN: JTEOAD

    Published Online: 1 March 2012

    Page Count: 14


    Ong, K. C. G.
    National Univ. of Singapore,

    Chandra, L. R.
    National Univ. of Singapore,

    (Received 15 February 2011; accepted 19 January 2012)

    Abstract

    Estimating the time at which to start monitoring early age shrinkage, especially of high performance cementitious materials, can be crucial. Despite numerous studies on early age shrinkage monitoring, there is no general agreement on the time at which early age shrinkage measurements should start (i.e., the “time zero” value [TZV]). The present paper proposes the use of the stiffening time measured via S-wave reflection loss as the TZV for early age shrinkage monitoring of high performance cementitious materials subjected to both sealed and unsealed curing conditions. The results imply that in the case of autogenous or sealed specimens, similar stiffening times occur throughout the specimen depths. In the case of unsealed specimens, however, the results show that the stiffening time might vary with depth depending on the water-to-cementitious ratio used. It is postulated that water redistribution within the specimen, as well as the formation of a “skin layer,” might significantly affect the stiffening time measured in the case of unsealed specimens used for early age drying shrinkage monitoring.


    Paper ID: JTE103820

    DOI: 10.1520/JTE103820

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    Author
    Title Time Zero Value Based on S-Wave Reflection Loss Measurement for Early Age Shrinkage Monitoring of Cementitious Specimens Subjected to Sealed and Unsealed Curing Conditions
    Symposium , 0000-00-00
    Committee C09