limit of free lime in clinker

Hello GKS,

For optimum clinker reactivity and cement performance, there is normally both a lower limit and an upper limit.  The lower limit for clinker is normally around 0.5% and the upper limit about 2.5%.

If clinker is produced with a free lime less than 0.5%, it is likely to be hard to grind and have a low reactivity, resulting in lower cement strengths.

If clinker free lime is much higher than 2.5% it is likely to cause unacceptable expansion in the cement, as well as lower cement strengths due to a corresponding reduction in the amount of C3S in the clinker.

Regards,

Ted.

Dear  sir Ted,

               But  i want clear for portland limestone cement.

              Any difference in chemical reaction of free lime for effecting cement strenght vs lime stone  added in clinker grinding for  PLC

              Why should not increasing free lime upto 5.0 % from 2.5 % limit with effecting C3S , C2S &C3A in clinker for optimisation of sp. heat of kiln .

            Regards

             GKS

Hello GKS,

The limits for clinker free lime are no different for PLC than they are for OPC. Both use the same clinker.

There is no reaction between free lime and limestone in PLC.

For the same raw meal LSF, clinker burnt to a free lime target of 5% instead of 2.5% would contain about 10% less C3S. This would reduce cement strengths.

PLC made with clinker containing 5% free lime would most probably be unsound due to excessive expansion.

Regards,

Ted.