FORMWORK (AS PER I.S.
456:2000)
NECESSITY OF FORMWORK :-
THE FORMWORK SHALL BE DESIGNED AND
CONSTRUCTED SO AS TO REMAIN SUFFICIENTLY RIGID DURING PLACING AND COMPACTION OF
CONCRETE AND SHALL BE SUCH AS TO PREVENT LOSS OF SLURRY FROM THE CONCRETE.
CLEANING AND TREATMENT OF FORMWORK :-
THE FACE OF FORM WORK IN CONTACT WITH
THE CONCRETE SHALL BE CLEANED AND TREATED WITH FORM RELEASE AGENT. RELEASE
AGENTS SHOULD BE APPLIED SO AS TO PROVIDE A THIN UNIFORM COATING TO THE FORM
WITHOUT COATING THE REINFORCEMENT.
STRIPPING TIME:-
FORM SHALL NOT BE RELEASED UNTILL THE
CONCRETE HAS ACHIVED A STRENGTH OF
ATLEAST TWICE THE STRESS TO WHICH THE CONCRETE MAY BE SUBJECTED AT THE TIME OF
REMOVAL OF FORMWORK.
STRIPPING TIME
|
S.NO
|
TYPE OF FORMWORK
|
MINIMUM PERIOD BEFORE STRIKING FORMWORK
|
|
(1)
|
VERTICAL FORMWORK TO
COLUMNS
|
16-24 hr
|
|
(2)
|
SOFFIT FORMWORK TO SLAB
|
3 DAYS
|
|
(3)
|
SOFFIT FORMWORK TO BEAM
|
7 DAYS
|
|
(4)
|
PROPS TO SLAB
SPANNING UPTO 4.5 M
SPANNING ABOVE 4.5 M
|
7 DAYS
14 DAYS
|
|
(5)
|
PROPS TO SLAB
SPANNING UPTO 6 M
SPANNING ABOVE 6 M
|
14 DAYS
21 DAYS
|
CONCRETE MIX PROPORTIONING MIX PROPORTION:-
(AS PER I.S. 456:2000)
THE MIX PROPORTIONS SHALL BE SELECTED
TO ENSURE THE WORKABILITY OF FRESH CONCRETE AND WHEN CONCRETE IS HARDENED, IT
SHALL HAVE THE REQUIRED STRENGTH, DURABILITY AND SURFACE FINISH.
THE DETERMINATION OF CEMCENT, SAND,
AGREEGATE & WATER TO ATTAIN THE
REQUIRED STRENGTHS SHALL BE MADE AS FOLLOW-
(A)
BY DESIGNING THE
CONCRETE MIX; SUCH CONCRETE SHALL BE CALLED ‘DESIGN MIX CONCRETE’.
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