There are other cement modules which are not frequently used or used only in particular cements/ regions/cement plants/countries etc., Lets see some of them.
Hardening ratio:
Hardening ratio = C3S/C2S
This is also called hardening module.The normal value of hardening ratio to be maintained between 0.5 to 8. Less than 0.5 of hardening ratio, the clinker or cement disintegrates by itself.Such cements are called belitic cements which have expansive property.
More hardening ratio leads to increase in initial strength of cement,increase in heat of hydration, but decreases the property of resistance to chemical attack.So if you want a cement of high early strength, you can go upto a hardening ratio of value 8 .
Always it is advisable to monitor hardening ratio for prodution of expansive cements/belitic cements/ flyash added cements and for special cements as increase in hardening ratio affects the resistance to chemical property of cement.
Note: Always remember that C2S is harder than C3S.
More hardening ratio leads to increase in initial strength of cement,increase in heat of hydration, but decreases the property of resistance to chemical attack.So if you want a cement of high early strength, you can go upto a hardening ratio of value 8 .
Always it is advisable to monitor hardening ratio for prodution of expansive cements/belitic cements/ flyash added cements and for special cements as increase in hardening ratio affects the resistance to chemical property of cement.
Note: Always remember that C2S is harder than C3S.
Calorie module:
Calorie module = (C3S+C3A)/(C2S+C4AF)
If the heat liberated from cement is more, then it leads to concrete cracking.If calorie module value is more, then the heat of hydration of cement will be more. So the calorie module value to be maintained between 0.3 to 1.8.
Calorie is heat.This module proportions the heat of hydration liberated from cement while mixing with water.(as you know the cement+water reaction is exothermic)
Note: Heat of hydration basically depends on three factors namely C3S,C3A and cement finess (as C3S & C3A reactions are very fast with water)
Silicic acid ratio:
Do you know what is silicic acid ?
Silicic acid → quartz + water
SiO2+2H2O→SiH4O4 (silicic acid)
Formula
Silicic ratio = SiO2/Al2O3
Formula
Silicic ratio = SiO2/Al2O3
Its the ratio between silica and alumina in raw material.
If this value was maintained between 2.5 to 3.6, then the cement plant kiln will have good coating tendency resulting extended kiln lining life.(but ensure that alumina ratio to be kept between 1.8 to 2.4)
This silicic acid ratio was not used in most of the cement plants.
(Silica ratio and silicic acid ratio are not same.Both are different.So never get confused)
Hydraulic index
Hydraulic index = (SiO2+Al2O3)/(CaO+MgO)
The normal range of hydraulic index for a good cement was 0.42 to 0.48.
The lime content was rated as per hydraulic index.More the hydraulic index,then material will be hard burning and grinding.The formula was mostly used once upon a time in france but not now.
If this value was maintained between 2.5 to 3.6, then the cement plant kiln will have good coating tendency resulting extended kiln lining life.(but ensure that alumina ratio to be kept between 1.8 to 2.4)
This silicic acid ratio was not used in most of the cement plants.
(Silica ratio and silicic acid ratio are not same.Both are different.So never get confused)
Hydraulic index
Hydraulic index = (SiO2+Al2O3)/(CaO+MgO)
The normal range of hydraulic index for a good cement was 0.42 to 0.48.
The lime content was rated as per hydraulic index.More the hydraulic index,then material will be hard burning and grinding.The formula was mostly used once upon a time in france but not now.
