Formwork is useful in concrete construction. It is a permanent or temporary structure in which constructors pour fresh concrete to harden subsequently. Formwork construction is not new and has always been useful in the construction industry for more than a thousand years. One of the most ancient formwork is the Pantheon, built in 120AD in Rome. Concrete is structurally robust in holding compressive loads. However, it has low tensile strength, the reason why the earliest concrete buildings with formwork consisted of domes, vaults, or arches.
In ancient times, the earliest formwork types were useful in masonry since concrete production was rare due to its complexity. In the 19th century, the prevalence of concrete increasingly grew with many constructors preferring concrete as a building material.
Formworks are commonly known according to the type of structure, for instance, a formwork for the slab, a beam formwork for use in beams, and column formwork for use in columns. A slab formwork comes in handy when a building requires suspended concrete slabs with no direct connection to the ground. It consists of formwork panels, shores, joists, stringers, and other supporting material. Slab formwork can be of different materials such as aluminum, metal, timber, or even plastic components to give shape and strength to the concrete structure. Slab formwork generally holds the weight of the concrete during the curing process.
Formwork construction is crucial and takes a lot of time, and resources-about 20-25% of the overall structure’s total cost.
The Various Types Of Formwork For Slab
With timber formwork, timber is useful for shuttering since exposed concrete work should have an even and smooth surface on all parts that come into contact with concrete. It should be free from loose knots, well-seasoned, easily workable with nails, and light in weight.
Steel formwork is of steel panels constructed out of thin steel plates. The constructor stiffens them along the edges using small steel angles, and the panels connect using bolts, clamps, or nuts. The panels come in different shapes or sizes and are commonly useful in large projects. They are most suited for curved structures or circular ones.
Here, the constructor attaches resin-bonded plywood sheets to timber frames to come up with suitable sized panels. Plywood formwork is almost similar to timber formwork. It may be cheaper because it uses large panel sizes, which saves labor costs in fixing or dismantling, and its number of re-uses is more than timber formwork.
What Makes A Good Formwork?
- It should be tough to hold all types of loads.
- The structure should be robust and adequately braced and propped up both horizontally and vertically for its shape.
- The construction of formwork should remove different parts of the structure as desired without affecting the concrete.
- The joints of the formwork should be as tight to avoid any leakage of cement grout.
- The formwork material should be readily available and reusable.
- It should have lightweight.
- It should stand on a firm base.
- The material of the formwork should not warp or distort when exposed to the concrete.
- The levels of the formwork should have a plain surface.
Having some insights about formwork for slab will help you make wise choices when renovating your home or venture into a construction project.