You are being redirected because this document is part of your ASTM Compass® subscription.
    This document is part of your ASTM Compass® subscription.

    Volume 9, Issue 1 (January 2012)

    Comparison of ASTM C311 Strength Activity Index Testing versus Testing Based on Constant Volumetric Proportions

    (Received 13 June 2011; accepted 3 August 2011)

    Published Online: 2011

    CODEN: JAIOAD

      Format Pages Price  
    PDF 7 $25   ADD TO CART

    Cite this document

    X Add email address send
    X
      .RIS For RefWorks, EndNote, ProCite, Reference Manager, Zoteo, and many others.   .DOCX For Microsoft Word



    Abstract

    Currently, the (pozzolanic) strength activity indices of fly ashes and natural pozzolans are typically evaluated using the procedures outlined in ASTM C311 [“Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete,” Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2007]. In this test, the 7 and 28 d compressive strengths of mortar cubes with a 20 % mass replacement of cement by pozzolan are compared to those of a control without pozzolan, at constant flow conditions. In its current form, this procedure confounds two other properties of the pozzolan with its strength activity, namely its density and its water-reducing/increasing capabilities. In this study, the current C311 testing procedure is evaluated against an alternative in which the 20 % fly ash replacement for cement is performed on a volumetric basis and the volume fractions of water and sand are held constant, which should provide a true evaluation of the strength activity index of the pozzolan, free of these confounding influences. Class C and Class F fly ashes, a natural pozzolan, and a sugar cane ash are evaluated using both approaches, with some significant differences being noted. For a subset of the materials, the strength measurements are complemented by measurements of isothermal calorimetry on the mortars to an age of 7 d. For the constant volumetric proportions approach, a good correlation is exhibited between the cumulative heat release of the mortar at 7 d and the measured 7 d strength, suggesting the potential to evaluate 7 d pozzolanic activity via calorimetric measurements on much smaller specimens.


    Author Information:

    Bentz, Dale P.
    National Institute of Standards and Technology,

    Durán-Herrera, Alejandro
    Universidad Autónoma de Nuevo León,

    Galvez-Moreno, Daniel
    Universidad Autónoma de Sinaloa, Los Mochis,


    Stock #: JAI104138

    ISSN: 1546-962X

    DOI: 10.1520/JAI104138

    ASTM International is a member of CrossRef.

    Author
    Title Comparison of ASTM C311 Strength Activity Index Testing versus Testing Based on Constant Volumetric Proportions
    Symposium , 0000-00-00
    Committee C09