Clinker cooling rate vs Cement Performance

Hello Norew,

Faster cooling of clinker has the following effects;-

1. Smaller C3A crystals resulting in a more reactive and easier to grind clinker, producing faster cement setting times, improved early strengths and increased water demand.

2. Prevents the decomposition of C3S into C2S and (sub-microscopic) free lime, resulting in improved cement strength, compared to slow cooled clinker.

3. Increases the chances of other elements (eg Mg, Al, Fe etc) being trapped in the crystal structure of the clinker silicate minerals. Such chemical substitutions cause the clinker minerals to become more reactive during hydration, thus increasing strengths and shortening setting time.

NOTE: These effects are relative to the degree of improvement in rate of cooling, and may be insignificant if there is only a small improvement in cooling efficiency.

Regards,

Ted.

Ted has given the actual details, Effect of different things on slow and fast cooling is given below, slow cooling means 4 to 5 degree per minute and fast cooling is 18 to 20 degree per minute.

MgO :Slow cooling: Forms pericles crystals ,Fast cooling : Light brownish yellow clinker

Alkalies (Na2O and K2O):Slow cooling: No much significant effect,Fast cooling : No much significant effect

Aluminate(C3A and C4AF):Slow cooling: remains in crystal form,Fast cooling : remains in glassy phase

Silicate phases( C3S and betta-C2S):Slow cooling: less active and less stable,Fast cooling : more active and stable 

Liquid formation:Slow cooling: crystalline to all clinker component ,Fast cooling : solidities to glass

Hydraulically active:Slow cooling: less ,Fast cooling : more

Particle size:Slow cooling: bigger ,Fast cooling : relatively smaller

Strength: Slow cooling: low early strength (3 to 7 days), Fast cooling : high early strength(3 to 7 days)

Grinding energy: Slow cooling: more,Fast cooling : less

Soundness:Slow cooling: less ,Fast cooling : more

Sulphate resistance: Slow cooling: less ,Fast cooling : more

Colour :Slow cooling: light brownish yellow ,Fast cooling : deep brownish yellow

vdchari

Hello Chari,

Thank you for reminding me of soundness, which I omitted in my list of the positive effects of fast clinker cooling;-

4. Fast clinker cooling results in small MgO crystal size which tends to reduce the likelyhood of cement unsoundness.

Regards,

Ted.