Cement Quality

Dear Sir,

We are facing problem of quick setting of concrete .

Consistency of cement has increased from 30 to 45 %

we have checked gypsum its ok, PI (Lime stone ok ,clinker ok )

We blaine is 3300 to 3500 )

Residue on 90 micron is zero and on 45 micron 12 %.

when in 1:1:2 ( 1 cement: 1 sand and 2 graval ) more water is added for free flowing it looks very creamy and slowly sets and hair line cracks appera. 3 days 7 days strength are ok.

please advise

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re Cement Quality

Try to reduce blain to 2900 -3000

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re Cement Quality

Cement quick setting:

• check the laboratory (Is the blaine value correct?)
• check the alkali content in clinker  (problem with false set and optimal gypsum level)
• if it is possible check the semy-hydrate gypsum content (Had the process engineer changed something i.e. mill outlet temperature e.t.c.?)

Cement water demand:

• check the laboratory (is the blaine value correct?)
• check the PSD less then 3 micron (is it increased?)

 Concrete quick set:

is the chemical-additive used for concret? You should take the archived sample from laboratory for the non-problematic period (it should be storaged) and check the concrete chemical-additive.

Regards

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