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disadvantage of super Plasticizer over dosage in rich cement con. mix

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NADOR123

Structural
Apr 3, 2007
49
I am reviewing a concrete design mix that is rich in cement about 752Ib per cubic yard (1120 Ib of sand and 1750 Ib of crushed gravel) 45 oz per yard of Glenium would be added at the site after verifying 3"+/- 1" initial slump the final slump as per lab for the above dosages is 6.25" and final allowable slump at the field is 6" +/- 1".
The contractor request to add more super P if the lab dosage is not giving the final slump with in the 6" +/- 1".
Is any disadvantage of adding additional amount of super P at the field and what is the percentage should be allowed to avoid segregation? The mix is 5000 PSi and the average compression test as per lab is 6420 PSi @ 28 days.
Is adding over dosage of super P accelerate the setting time that requires early curing( we has a surface cracking problem with a cement rich mix at the time of pouring the slab of the tanks ( 620 Ib of cement per cubic yard)and the new mix is for the walls of the tanks.


 
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