ISSN: 0149-6123
Page Count: 8

A Kinetic-Based Method for Interpreting ASTM C 1260
Johnston, D
South Dakota Department of Transportation, SD

Stokes, D
FMC Corporation, NC

Surdahl, R
Federal Highway Administration, CO

Abstract

A proposed kinetic-based method for interpreting ASTM C 1260 test results is introduced that appears capable of overcoming some of the shortcomings currently encountered using a percent expansion criterion for defining potentially reactive aggregate. The method is based on nucleation and growth or phase transformation reaction kinetics where the percent expansion is exponentially related to a power of time. Solving the logarithmic form of the kinetic equation by a least-squares fit yields two parameters, lnk and M, where lnk is the intercept and M is the slope of the regression line, which can be used to determine potential reactivity. A plot of M versus lnk yields two separate domains—one containing reactive aggregate and one containing innocuous aggregate. Values of lnk < -6 are associated with innocuous aggregate. The method successfully differentiated between several reactive aggregates with 14-day expansions of less than 0.1% as reactive and indicated that one aggregate with a 14-day expansion of 0.278% was innocuous. The method also appears promising with regard to determining effective levels of pozzolans and other admixtures for mitigation of ASR reactive aggregate.

Keywords:
aggregate, pozzolans, nucleation

Paper ID: CCA10474J
DOI: 10.1520/CCA10474J
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