Fineness of Cement

             A fineness of Cement is measure size of the particles of the cement.

Penetration  Instrument

• It can be calculated from site distribution or from the One of the air permeability
• It is an important factor determining the rate gain of the strength and uniformity of the quantity.
• For given weight of the cement surface area is more for fineness cement than worse cement.
• The finer cement is higher than rate of the hydration as more surface available for chemical reaction resulting in the early development of the strength.The Effect of fineness on the compressive strength as shown in fig.

• If the cement is ground beyond certain limit ,it properties may be mixed adversely affected due to hydration by atmospheric moisture.
• Excessive fineness is also undesirable because cost of grindingness  of cement of higher degree of fineness is considerable and requires great amount of gypsum through rectangle.

• Fineness of Cement:

  Cement is measured in terms of % of weight and retained through 90mm seive.
  
  
  • Surface area of cement particular is sq.cm/gm.
  • IS 269-1967 specifies that maximum residue after seeing through 90umm should be limit 105 of OPC.
  • IS  269-1967 specifies air permeability and lays down that specifies surface in sq.cm/gm of cement and calculated by this method shouldn't less than 2530 sq.cm/gm.