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Computers and Concrete
  Volume 20, Number 2, August 2017 , pages 197-204
DOI: https://doi.org/10.12989/cac.2017.20.2.197
 


Effect of fineness of high lime fly ash on pozzolanic reactivity and ASR mitigation
Kaveh Afshinnia and Prasada R. Rangaraju

 
Abstract
    Typically, high lime fly ash (Class C) has been characterized as a fly ash, which at lower replacement levels is not as effective as the low lime (Class F) fly ash, in mitigating alkali-silica reaction (ASR) in portland cement concrete. The influence of fineness of Class C, obtained by grinding virgin fly ash into finer particles, on its pozzolanic reactivity and ASR mitigation performance was investigated in this study. In order to assess the pozzolanic reactivity of mortar mixtures containing virgin or ground fly ashes, the strength activity index (SAI) test and thermo-gravimetric analysis (TGA) were conducted on the mortar cubes and paste samples, respectively, containing virgin fly ash or two ground fly ashes. In addition, to evaluate any improvement in the ASR mitigation of ground fly ashes compared to that of the virgin fly ash, the accelerated mortar bar test (AMBT) was conducted on the mortar mixtures containing different dosages of either virgin or ground fly ashes. In all tests crushed glass aggregate was used as a highly reactive aggregate. Results from this study showed that the finest fly ash (i.e., with an average particle size of 3.1 microns) could increase the flow ability along with the pozzolanic reactivity of the mortar mixture. However, results from this study suggested that the fineness of high lime fly ash does not seem to have any significant effect on ASR mitigation.
 
Key Words
    class C fly ash; fineness; pozzolanic reactivity; ASR; mitigation
 
Address
Kaveh Afshinnia and Prasada R. Rangaraju: Glenn Department of Civil Engineering, Clemson University, Clemson, SC 29634, USA
 

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