I am working on an experimental involving fly ash (that has 0.01% CaO content), lime powder and Cement. I have to perform thermogravimetric analysis on my samples to ascertain Ca(OH)2 content to relate it to hydration activity in the binder paste. Just wondering how the results having (i) cement and fly ash (ii) cement, fly ash and hydrated lime powder can be normalised to the control mix i.e. cement paste.
My main concern is if a mix design has high volume fly ash content (that has 0.01% CaO content), say for instance 60% fly ash and 40% cement, it will have relatively very low Ca(OH)2 content as compared to OPC mix (that contains very high lime content). Comparing these two mixes based on their Ca(OH)2 content at a certain age wouldn't be a true comparison because of a big difference in their respective lime contents.
best to normalize it to g Portland cement, in that way you can see directly how much Ch has been consumed due to the reaction of the FA. In addition normalize all measurements to dry weight (corresponding to the weight recorded at high temperature (either before or after the carbonate peak), as the total weight of your solid increases during hydration
Dear Barbara,
Thanks a lot for your reply. Could you please elaborate on how can i normalize the results to OPC. Say if i have the following two mixes (i) 40% cement and 60% fly ash (ii) 30% cement, 60% fly ash and 10% hydrated lime
I would suiggest
i) CH(measured)/0.4/(1-bound water) can be compared to Ch measured in a 100% portland cement (CH(measured)/(1-bound water)
ii) ((CH measured)/(1-bound water)-0.1/56*74)/0.3
the expression /56*74 relates your added lime to CH
Thanks Barbara, I really appreciate your great help.
Just wanted to clarify about 0.1/56*74. Does 0.1 equates to 10% additional lime i.e. 10/100 = 0.1 and
How does 56*74 relates to added lime i.e. how these numbers have come up 56, 74 and why they are multiplied?
This clarification would fully resolve my question
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