FORMWORK (AS PER I.S. 456:2000)

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’.

BY ADOPTING NOMINAL CONCRETE MIX; SUCH CONCRETE SHALL BE CALLED ‘NOMINAL MIX CONCRETE’.