Influence of Fineness and Soluble Silica Content of Fly ashes on Their Strength Development With Respect to Age

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Title: Influence of Fineness and Soluble Silica Content of Fly ashes on Their Strength Development With Respect to Age

Author(s): R. V. Ranganath, R. C. Sharma, and S. Krishnamoorthy

Publication: Special Publication

Volume: 153

Issue:

Appears on pages(s): 355-366

Keywords: cements; concretes; fineness; fly ash; lime; silica; solubility; strength; Materials Research

Date: 6/1/1995

Abstract:
The authors have examined the lime-reactivity strength data of 14 samples of fly ash obtained from different thermal power plants of India. The sand-lime-fly ash mortars cured at 50 C and relative humidity of 90 percent were tested in compression at different ages up to 90 days. It was found that lime reactivity is best correlated with combined parameters of fineness and soluble silica content, rather than with each parameter considered individually. Also examined were the strength of concrete mixtures in which part of the cement is replaced by a low reactive fly ash. Fineness of fly ash and testing ages for strength were the variables. It is concluded that the soluble silica content was related to later-age strengths, while the early-age strength correlated better with fineness of fly ash. The mechanism for the latter may not be chemical, but physical, such as dispersion of cement particles or micro-filler effect.