Monday, 25 July 2022 / Published in Formwork

Deshuttering Period as Per IS 456 – 2000

Deshuttering Period as Per IS 456 – 2000

The deshuttering period is one where the shuttering mold is removed. This is done when the concrete reaches maturity and is highly dependent on the ambient temperature. This process requires certain precautions, and specific knowledge is necessary to ensure that the removal process is flawless and up to standards.

The formwork is prepared with a variety of materials, including plastic, plywood, steel, etc. However, the material of the formwork will not influence the disassemble period.

 

IS Code for Concrete Formwork Removal

IS Code 456 specifies the removal of formwork for different kinds of concrete elements.

 

Formwork Removal Time for Varying Concrete Elements

Here is a list of various concrete elements and their formwork removal time:

  • Vertical formwork of wall, column and beam- 16-24 hours
  • Removal of props under-slab up to 4.5 meters- 7 days
  • Soffit to beams props- 7 days
  • Removal of props under arches and beams up to 6 meters- 14 days

 

When should Formwork Removal be Initiated?

Once the concrete has undergone at least twice as much stress as it may have at the time of removal, the shuttering can be removed.

In layman’s terms, the maturity of the concrete determines when the form should be removed. When the concrete reaches its design strength through hardening and can withstand the load occurring on its own, the de-molding process can be started.

Concrete progressively and over time develops its compressive strength.

Can Modern Formwork Systems Reduce Deshuttering Time?

The deshuttering periods specified in IS 456:2000 are general guidelines intended to ensure that concrete has developed sufficient strength before formwork is removed. However, modern formwork technologies are designed to optimize the construction cycle while still complying with these structural requirements.

For example, some advanced slab formwork systems use a drop head mechanism, which allows the slab panels to be removed earlier while the supporting props remain in place to continue carrying the load. Since the props are not removed, the slab continues to receive adequate support as the concrete gains strength.

This approach offers several practical benefits on site:

  • Enables earlier reuse of slab panels on subsequent floors.
  • Reduces the amount of formwork required for repetitive floor cycles.
  • Improves material utilisation and site productivity.
  • Helps maintain faster construction schedules without compromising structural support.

It is important to note that early panel removal does not mean early prop removal. The supporting props should remain in position for the duration recommended by the structural engineer and the applicable provisions of IS 456:2000. The actual deshuttering schedule should always be based on concrete strength, span, loading conditions, curing, and site-specific engineering assessments.

 

Factors that Influence the Formwork Removal Process

The process of removing the shuttering is influenced by certain factors and elements that are involved in the construction process. In the case of some special concrete or admixture, the shutter removal process can vary.

Some other factors that affect the formwork removal process are as follows:

  • Types of Cement

Cement that sets quickly and cements with rapid hardening will reach greater strength in a shorter time period than other types of cement.

  • Temperature

Higher temperatures cause the cement to hydrate more quickly and the concrete to harden more quickly. However, due to the cement’s rapid hydration, shrinkage cracks also appear at the same time.

  • Concrete Grade

A superior grade of concrete gives optimal strength in the shortest time, subsequently making the concrete formwork removal process quicker.

  • Cement Grade

The compressive strength value will impact the proportion of strength and growth, which varies between OPC 43 and OPC 53. The formwork removal duration varies due to this.

 

Precautions to Keep in Mind While Deshuttering

Dismantling of formwork requires some necessary precautions for the workers’ welfare and the quality of work. Here are some general precautions that should be upheld during the stripping of formwork.

  • Always make sure that the necessary safety arrangements are handy.
  • Appropriation supervision is required during the process to ensure the quality of the concrete.
  • If you notice honeycombs on the surface of the concrete, rectify them immediately to avoid further complications.
  • Ensure proper curing of the concrete.

 

Final Words

The de-molding process, according to IS 456-2000, is fairly straightforward. However, it is essential to know the guidelines and precautions while dismantling the framework. In addition, understanding the factors influencing the disassemble process can help you provide better services.

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