Raj Sahu
198 posts
TimePosted 10/08/2009 13:58:14
Raj Sahu says

White Cement

Dear Dr.Clarke,

I am sending you mineralogical ,chemical and physical characterization data of white cement.The said plant is using CaF2 as a mineralizer and using 100% petcoke fired kiln.We seek your help to know the possible causes and remedial measures of improving setting time of the cement-1.The analysed data are as given below:

 

Parameters Cement-1    Cement-2
C3S 53.1   63.6
C2S 40.56   28.94
C4AF 1.49   0.65
C3A ( C ) 0.83   2.63
C3A ( O ) 0.15   0.34
C11A7.CaF2 , Calcium aluminum oxide fluoride
Relatively more   Relatively less
Periclase 0.62   0.4
Arcanite 0.48   1.17
Gypsum
2.11
  1.38
HemiHydrate, 0.59   0.7
Anhydrite 0.07   0.13
Reactivity of cement by XRD hydration study Relatively less   Relatively more
Blaine , m2/Kg 411.00   416.00
Fluoride,By ISE-Fluoride 0.35   0.22
Setting Time:      
IST , in minutes 50   100
FST , in minutes 105   160

 

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Michael Clark
312 posts
TimePosted 10/08/2009 16:49:42

Re: White Cement

The short setting time of Cement 1 is clearly due to the formation of C11A7.CaF2. This is a component of "Jet" cement and exhibits rapid setting. The burning conditions in the kiln when this clinker was produced need to be analysed to ascertain why this compound was formed and then those burning conditions must be avoided.

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electron1539
50 posts
TimePosted 11/08/2009 06:53:47

Re: White Cement

Dear All,

 i want to clarify something , the addition of CaF2 as miniralizer lead to increase the setting time , why in that case the setting time is decreased  to this stage ....also C3A will be high , how come C3A Ortho and cubic Sum will be 0.89 %  ... i donot understand , could u clarify this issue to me Dr. Clark

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Raj Sahu
198 posts
TimePosted 11/08/2009 10:53:20
Raj Sahu says

Re: White Cement

As per my understanding in clinker doped with CaF2,the phase C3A is gradually replaced by calcium flouroaluminate (C11A7.CaF2).Due to presence of high CaO in calcium flouroaluminate reactivity of the phase is very high which leads to accelerate hydration reaction and consequently early setting is observed.

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