Cement testing:

How to avoid the pack setting ?

 

Hello Sundar,

Pack-set is a phenomenon related to the resistance to flow of stored cement. It can therefore have both chemical and physical causes. eg;-

1. Electric charges on the surface of the cement particles combined with compaction due to transport and/or storage.
2. Dehydration of gypsum in hot cement resulting in partial pre-hydration and syngenite (K2SO4.Ca2SO4.H2O) formation.
3. Partial hydration of bulk stored cement due to silo temperature and humidity.

Pack-set can be controlled by;-

1. The use of appropriate grinding-aids to reduce static electric charging of cement particles.
2. Careful control of cement mill exit temperature and cooler operation to prevent storage and transport of hot cement.
3. Control of cement storage environment. eg. humidity.

More detailed information, including a standard method for the determination of pack-set, can be found here;-

http://www.cement.org/manufacture/man_packset.asp 

http://www.astm.org/Standards/C1565.htm 

or by searching the internet.

 

Regards,

 Ted.

Dear TED,

 

Is there any relation with Limestone addition for pack set?

With regards,

Sundar 

 

Cement testing:

Is there any relation with Limestone addition for pack set?

Hello Sundar,

No, not that I am aware of. However if you intend to begin using limestone as a mineral filler, you should also check the tendency of your product to pack set when you do your plant trial... just to be sure.

Regards,

Ted.

In what way CO2 production is reduced in producing concrete when portland cement is replaced with limestone?