fly Ash Percentage in PPC Cements

Question

Different Cement companies have maintain different % of Flyash in cement. what are the advantage and disadvantage of Higher / Lower % of flyash in cement.

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deayan 4 months 4 Answers 1422 views 0

Answers ( 4 )

  1. Fly as is a by product of power station furnaces fired by pulverized bituminous coal. It replaces portion of concrete and hence improve sustainability of structures. Any replacement percentage can be considered provided that project requirement and specifications are not compromised. For example, concrete strength shall be the same of nearly the same of concrete without replacement materials.

    Generally, fly ash reduce heat of hydration, improve sulfate resistance, reduce chloride diffusivity, minimize risk of alkali aggregate reactivity, environmentally friendly, and improve concrete economy.

    As the percentage of replacement is increased, these advantages would manifest themselves better. However, higher percentages may decline ultimate concrete strength, and concrete need strict curing regime since early strength development of concrete with fly ash is low.

    In contrary, low replacement percentage would provide more certainty regarding strength of concrete, but the replacement would not be effective.

    In summary, suitable replacement percentage is not the same for all structures. Each condition shall be investigated and suitable replacement quantity shall be determined.

  2. I herd that, the un-burnt carbon present in fly-ash effects concrete adversely. can u explain the same?

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