What Is Formwork in Construction?
What Is Formwork in Construction?
Formwork, also known as shuttering, is a temporary mold used in concrete construction to shape and support wet concrete until it hardens.
There are various types of formwork materials and designs, each suitable for different types of structures such as slabs, beams, and columns. The construction of formwork can be time-consuming and costly, sometimes accounting for up to 25% of the total cost of the structure.
Careful design is necessary to ensure that the formwork is cost-effective and can be easily removed, a process known as stripping. Formwork can be reusable, in which case it is called panel formwork, or it may be discarded after use, known as stationary formwork.
There are several types of formwork used in construction: traditional timber formwork, engineered formwork systems, reusable plastic formwork, permanent insulated formwork, stay-in-place structural formwork systems, and flexible formwork.
Traditional timber formwork is made on site using timber and plywood or particleboard and is commonly used where labor costs are lower. Engineered formwork systems are prefabricated and made with a metal frame and covered on the concrete side with the desired surface material.
Reusable plastic formwork is made from interlocking and modular systems used to build simple concrete structures. Permanent insulated formwork is assembled on site using insulating concrete forms and stays in place after the concrete has cured.
Stay-in-place structural formwork systems are also assembled on site using prefabricated fiber-reinforced plastic forms, which are often used for columns and piers.
Flexible formwork uses lightweight, high strength fabric sheets to take advantage of the fluidity of concrete and create unique building forms.
What Is The Function Of The Formwork?
Formwork is a temporary structure used to shape and support concrete as it hardens. It is essential in the construction of monolithic concrete and reinforced concrete structures or components, such as foundations, columns, containers, chimneys, hydraulic structures, bridges, towers, and public buildings.
The formwork must be in place before the necessary steel reinforcement and concrete mix are added, and it must be strong enough to hold the concrete in place but not too strong, as it will need to be removed after the concrete has hardened.
Improperly made formwork can cause material damage or injuries, while excessively strong formwork can be difficult and costly to remove.
Formwork requires specialized knowledge and attention to the direction of forces when placing the concrete mix to ensure both structural integrity and ease of removal.
What Determines When Formwork Can Be Removed From Cast In Place Concrete?
Formwork is a temporary structure used to hold wet concrete in place as it hardens. It is set up in the desired position and held in place until the concrete has gained sufficient strength, known as the formwork striking time.
Once the concrete has reached this point, the formwork can be safely removed. Before removing the formwork, it is important to ensure that the concrete structural elements supported by the formwork have been removed and the concrete has fully hardened.
If the formwork is left in place for too long, it can cause stress on the structural dimensions and potentially damage the concrete. To avoid this, it is important to follow proper precautions and remove the formwork at the appropriate time.
What Are Release Agents In Concrete Formwork?
Release agents are coatings applied to the surface of formwork or shuttering prior to pouring concrete. They provide a barrier between the mold and the substrate, allowing for easy separation of the cured concrete from the mold.
Without a release agent, the substrate could become fused to the mold, resulting in difficulty in clean-up and reduced production efficiency.
There are two types of release agents commonly used in the concrete construction industry: barrier and reactive. It is important to store release agents in accordance with the manufacturer’s recommendations and to avoid contamination or dilution.
Release agents should have a long shelf life and be able to withstand extreme temperature changes and rough handling. It may be necessary to stir the release agent to ensure uniformity, and care should be taken to avoid sediment.
In some cases, release agents contain volatile solvents which should be stored in airtight containers to prevent a change in concentration.
The quality and consistency of the finished product can be affected by factors such as irregular application or improper choice of release agent.