Correct Answer - Option 1 : 1 day
Concept:
As per IS: 456-2000 clause 11.3.1
In normal circumstances where ambient temperature does not fall below 15°C and where ordinary Portland cement is used and adequate curing is done, following striking period may deem to satisfy the guideline given below.
S.No.
|
Type of formwork
|
Minimum period before striking formwork
|
01
|
Vertical formwork to columns, walls, beams
|
16-24 hour
|
02
|
Soffit formwork to slabs (Props to be fixed immediately after removal of formwork)
|
3 days
|
03
|
Soffit formwork to beams (Props to be refixed immediately after removal of formwork)
|
7 days
|
04
|
Props to slabs:
1) Spanning up to 4.5 m
2) Spanning over 4.5 m
|
7 days
14 days
|
05
|
Props to beams and arches
1) Spanning up to 6 m
2) Spanning over 6 m
|
14 days
21 days
|
For normal M20 reinforced concrete, the time of removing the vertical form work for columns as per IS 456 is 1 day.