537 posts
Re: Pet Coke
There is another factor which can cause low strengths in cement made from high SO3 clinker.
In excess of that required to form soluble sulphates with the alkalis, SO3 dissolves in the silicate phases, particularly C2S.
This causes stabilisation of C2S which retards its reaction with CaO to form C3S, ultimately resulting in significantly higher amounts of C2S in the clinker than would be expected by the Bogue chemical predictions.
This results in a strength drop in the cement. However, sulphate stabilisation of C2S can be offset by the addition of fluoride.
Regards,
Ted.
References:
A. Emanuelson, S. Hansen, E. Viggh, "A comparative study of ordinary and mineralised Portland cement clinker from two different production units Part I: Composition and hydration of the clinkers", Cement and Concrete Research 33 (2003) 1613–1621.
W.Tiano, G. Artioli,"Influence of Minor Elements, in particular SO3, on the Clinkerisation Process", ESRF Report #CH1724, Università di Milano, April 2004.
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108 posts
537 posts
Re: Pet Coke
Dastgir:
Little confusion. Due to non conversion of C2S to C3S, because of high SO3, latter strength should have increased, but what we observe is decrement.
Hello Gulam,
Maybe I should have said. "This causes stabilisation of C2S which retards its reaction with CaO to form C3S, ultimately resulting in significantly lower amounts of C3S."
Since C3S formation is retarded, it is the decrease in the C3S/C2S ratio that causes the drop in strengths. The strength contribution of C2S is substantially lower than that of C3S at 3, 7 and 28 days. Therefore overall, a reduction in C3S is not equally compensated for by a corresponding increase in C2S.
If this was not the case, there would be no reason to optimise and control the C3S content of OPC clinker.
Regards,
Ted.
108 posts