ISSN: 0149-6123
Page Count: 5

The Autoclave Soundness Test Mischaracterizes Cement-Fly Ash Blends By Introducing Alkali-Quartz Reaction
Wang, H
Cemex Inc., FL

Abstract

ASTM C311 is widely used to evaluate the soundness of cement-fly ash blended systems. The soundness test is performed according to ASTM C151—an autoclave test to determine the soundness of portland cement. It has been known that excessive autoclave expansion of cement- fly ash blends occurs in some cases, but the expansion sources and mechanism are poorly understood. Present work in this paper investigated the autoclave expansion conditions of the cement—fly ash blends, major sources of the expansion and expansion mechanism. Based on the test results, it was found that the major source of autoclave expansion of cement—fly ash blend is due to alkali-quartz reaction under autoclave conditions. This excessive expansion due to alkali-quartz reaction did not occur even in the most severe test conditions in ASTM C1260. Therefore, it is reasonable to believe that ASTM C151 mischaracterizes the soundness of cement—fly ash blended systems by introducing an unintended side chemical reaction—alkali-quartz reaction.

Keywords:
autoclave test, autoclave expansion, soundness, periclase, ASTM C311, ASTM C1260, ASTM C151, ASTM C-618, alkali-silica (quartz) reaction, fly ash

Paper ID: CCA10528J
DOI: 10.1520/CCA10528J
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