written by: Engr Sami Ullah Stanikzai. www.civilglobal.com
In this Article I will show you that what is the formwork removal time Or De-shuttering of formwork in detail.
briefly explains the process required for de-shuttering of formwork as well as the time period to remove the formwork from column, walls, beam, slab, staircase, foundation footing etc.
Removal of formwork:
The timing of removal of formwork can depend on the rate of strength gain of the concrete. and we can remove the formwork with different days.
(a) Vertical surfaces can be struck when the concrete is strong enough to resist the adhesion on the concrete/form face surface.
(b) Soffits cannot be struck until the concrete has gained sufficient strength for the element to support is self weight for all or part of the structural span. It is possible to speed up the removal of much soffit formwork by removing a small part of the formwork and then installing props to this area. Another area of formwork can then be removed and props installed props. This sequence can be repeated until all the formwork has been remove and the soffit is fully propped.
The removal of concrete formwork is also known as strike-off or stripping of formwork. It is should be performed when the concrete obtains adequate strength.
The formwork should, under no circumstances, be allowed to be removed until the concrete reaches a strength of at least twice the stress to which the concrete may be subjected to at the time of removal of formwork.
While removing formworks, the following points should be taken into consideration.
• freeze thaw damage • development of cracks because of thermal contraction of concrete
Special consideration should be given for formwork removal of flexural members like beams and slabs because these members are dependent on self-load and live load even throughout construction, they may deflect if adequate strength is not obtained to manage the loads.
Detail information is given below.
For column/walls, vertical form works should be detached after 16 to 24 hours.
Soffit formwork to slab (formwork is located under the slab), the form works can be removed after 3 days. (props should be reaffixed once the removal is done).
Soffit formwork to beam, the form works can be removed after 7 days. (props should be reaffixed once the removal is done.)
Beam that spans up to 4.5 m (length), the form works can be removed after 7 days.
Beam that spans surpassing 4.5 m (length), the form works can be removed after 14 days.
For footing, the form works can be removed after 16 to 24 hours.
For staircase, the form works can be removed after 5 days.
These are the removal of formwork time which should be remove in the above days which i have discussed with you. if you remove the formwork before the removal days , than it will be make many problems for the structure. therefore we should remove with the fix days.
note: The above day’s to remove the formwork I have taken from IS codes and these are the actual days by which we can remove the formwork, in these day’s the concrete can gain the twice strength, which hare requried for our design project.
Written by: Engr Sami Ullah Stanikzai (www.civilglobal.com)