Concrete works

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Concrete ;A homogeneous mixture of --








•Concrete compaction must attained to reduce entrapped air content and flow concrete mixture. Not more than 2% air content acceptable in fresh concrete.
•Compaction executed by needle vibrator rpm varies from 1000 to 15000.
•Vibrator immerge in concrete vertically and retain in concrete  from 30 second to 2 minutes.
•Vibrator must placed  not more than @ 600mm or  8-10 times diameter of needle.
•Needle are available for concrete compaction 40 to 100 mm diameter.
•Concrete pour by layer wise and in no cases layer not be more than 600 mm thick.
To feed bonding hydration process concrete curing immediately need to attain on hardened surface.
Impervious sheeting or burlap cloth @ 290gm/sqm, membrane  curing compound or potable water can be used for the purpose according to availability and approval.
Continuous curing upto 72 hrs minimum required and at least 7 days proposed as per ACI301.
 Upon curing efficiency desired concrete strength can achieve and formwork may removed  accordingly—
Vertical strut structure like Wall, column or pier formwork may removed @ 40% gaining of 28 days compressive strength.
Beam ,slab bottom shutter may remove only after attain @ 85% of  28 days compressive strength.
Concrete strength fck refers for 28 days cylinder compressive strength.
Cylinder strength = 0.8 times of 28  days cube strength.
Structural concrete slump 100mm,125 mm in respect without plasticizer and with plasticizer.

Cylinder to collect one set (4nos in each set) for each 100 Cum or 400 Sqm of surface area placed.
Concrete cast in slope placed first portion then monolithically toward the higher elevation.
No horizontal construction allowed during casting of beam.
All projected corners to be chamfered 20 X20 in general.
All cast in embedment's need to verify. Any item permanently exposed must  be hot dipped galvanized/stainless steel. 
Defective/unused holes to be fill with non-shrink grout.
Specifications followed as per local and ACI 318,304 code.



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