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Minimum de-shuttering period of formwork & props as per IS-456/Stripping time of column, beam, & slab.

In the  IS-456 (2000), the de-shuttering period or stripping time for the RCC structure is mentioned in detail, and let us discuss them with the required drawings for a clear understanding.

The de-shuttering period mentioned below only holds good, if the following three criteria or conditions are fulfilled.

Conditions:

1. The ambient temperature should not fall below 15°C.

2. The cement used for the concreting should be ordinary portland cement (OPC ).

3. Adequate curing is done.


The minimum De-shuttering period or stripping time:

1. Vertical formwork to columns, walls, & beams.      👉   16 - 24 hours.


Formwork in a column.

As you can observe in the above drawing, the vertical formwork & props of the columns can be removed after 16 to 24 hours. To be on the safer side & to maintain the column edges, it is better to de-shutter after 24 hours of time.



The vertical formwork for the beam, as shown above, can be removed after 16 - 24 hours. But you cannot remove the soffit formwork and props.

2. Soffit formwork to slabs     👉   3 days.

[ Props should be refixed in the same position immediately after the removal of the formwork.]


As you can observe in the above diagram, the formwork i.e. given at the bottom part (horizontal ) of the beam or slab is called the soffit formwork.

For the slabs, you can remove the soffit formwork after 3 days, but the condition is, that you have to immediately refix the props i.e. given as vertical support to the formwork, as shown in the below drawing.


3. Soffit formwork to the beams     👉  7 days.

[ Props should be refixed in the same position immediately after the removal of the formwork.]

For the beams, you can remove the soffit formwork after  7 days, but you have to immediately refix the props in their vertical position( as shown in the above drawing ), to support the RCC structure.


4. Props left under the slabs can be removed for 



a )  A slab of span i.e. less than or equal to 4.5m.    👉  7 days.

b )  A slab having a span over 4.5m.                        👉  14 days.

As shown in the above drawing, if the clear span of the slab is less than or equal to 4.5m., the props can be removed after 7 days. If the slab has a longer span i.e. greater than 4.5m., the props should be removed after 14 days. Here, always the longer span of the slab is considered to remove the props.


5. Props left under beams & arches can be removed for


a ) A beam or arch of a span i.e. less than or equal to 6.0m.  👉 14 days.

b ) A beam or arch having a span above 6m.                          👉  21 days.


The refixed props can be removed according to the span of the RCC beam & arches. 

As shown in the above drawing, if the clear span of the beam is less than or equal to 6.0m., the props can be removed after 14 days. If the beam has a longer span i.e. greater than 6.0m., the props should be removed after 21 days.

Note: Usually in individual residential buildings, the props are removed along with the formwork. In such conditions, always you have to follow the stripping time of props for de-shuttering.


To get the answer to more such construction-related FAQsclick here.

Thank you for going through this article. Have a good day😄


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