Off-form concrete is a construction material made by pumping concrete through a nozzle which forms it into a predetermined shape.

This project can be done to create wall panels, floor tiles and ceiling tiles quickly with little waste of materials or time on site.

It is also possible to create more irregularly shaped items, such as chairs and tables. Because of its composition of cement and sand it is very strong.

It can be used for building concrete furniture pieces with a unique design.

Off-form concrete is normally used by professionals in the construction industry, but it can be done at home with no special equipment. The steps include mixing sand and cement to form a base layer for the nozzle to easily push through. Once this has been done, adding colour additives will give the concrete its final colour. Finally, water must be added to help the concrete move smoothly through the nozzle.

How is off-form concrete made?

  1. Mix the cement and sand together in a mixer until it has formed into a solid base layer. The thickness of this base layer should be such that it can help produce the desired product (for example, for making tabletops, about 0.2 m to 0.25 m thick).

  2. Now add water and stir to obtain a mixture with the consistency of cream which is easily pourable but not too runny in order to avoid spills and wastage in later steps in situ.

  3. Finally add any colour additives required, stirring them to a large degree with a drill-mounted paddle attachment.

  4. If a spray nozzle is to be used for the next step, it must first be attached and tightened securely to a standard water hose which should be connected to a tap or other source of clean water in sit under pressure.

  5. The nozzle itself consists typically of three parts: a knobbed ring onto which the mould will fit; a cylindrical piece containing the hole through which the concrete will pass; and finally an end piece with its own handle. In order to achieve different break effects from the same nozzle, all three components may sometimes need to be changed as well as their angles in relation to each other.

  6. When off-formwork has been poured into a mould, it must cure until strong enough not to deform before it can be removed from the mould. Note that the exact time required for this project depends on factors such as the thickness of the product and the ambient temperature, but it is often several days.

Off-form concrete surface finish variations

Off-form concrete is a construction material created by pumping concrete through a nozzle which forms it into a predetermined shape. This can be done to create wall panels, floor tiles and ceiling tiles quickly with little waste of materials or time-consuming projects. It can also be used to create more irregularly shaped items, such as chairs and tables using a different method. Off-form is made by mixing sand and cement with water until it has formed into a solid base layer. Then the mixture must be added by pouring into any colour additives required to obtain the desired colouration, stirring them thoroughly with a drill-mounted paddle attachment.

Finally, if a spray nozzle is used for the next step, it must first be attached and tightened securely to a standard water hose which should be connected to a tap or other source of clean water under pressure. The nozzle itself consists of three parts: a knobbed ring onto which the mould will fit; a cylindrical piece containing the hole through which the concrete will pass; and finally an end piece with its own handle.

When it has been poured into a mould, it must cure until strong enough not to deform before it can be removed from the mould.

What is the off-form concrete used for?

Off-form is best known for its use in construction to create wall panels, floor tiles and ceiling tiles quickly with little waste of materials or time. It can also be used for building more irregularly shaped items, such as chairs and tables. Off-form concrete is made by mixing sand and cement combined with water until it has formed into a solid base layer. Finally, if a spray nozzle is used for the next step, it must first be attached and tightened securely to a standard water hose which should be connected to a tap or other source of clean water under pressure. The nozzle itself consists of three parts: a knobbed ring onto which the mould will fit; a cylindrical piece containing the hole through which the concrete will pass; and finally an end piece with its own handle. When off-form concrete has been poured into a mould, it must cure until strong enough not to deform before it can be removed from the mould. Off-form concrete surfaces finish variations Off-form concrete is often used as a supportive element in architecture as opposed to being structural itself. In this sense, off formwork can both provide structure as well as serve as finishing materials. The basic idea of using off formwork for architecture is that suspended floors are able to bear their own weight by having wall panels interposed between them instead of requiring loads bearing walls and this is generally preferred as this can help save overall cost. This process achieved open environment with the affect of greater flexibility of spaces and potential for larger rooms.

Does off form concrete need treating?

It is vital that concrete mix designs are carefully planned and controlled when they are used for off form concreting. Concrete must be allowed to cure before it can be safely removed from the mould in which it is formed. If this does not happen, the concrete will deform and no longer hold its shape. It can even shatter if removed too suddenly or with excessive force, potentially causing injury to workers and surrounding objects.

Off-form concrete surface finish variations

Off-form concrete is often used as a supportive element in architecture as opposed to being structural itself. In this sense, off-formwork can both provide structure as well as serving as finishing materials. The basic idea of using off form for architecture is that suspended floors are able to bear their own weight by having wall panels interposed between them instead of requiring load-bearing walls. This results in a more open environment with greater flexibility of spaces and potential for larger rooms.

Finishing materials are not treated because it does not require any treatment other than what would be necessary for off-form concrete used in general construction. However, the moulds themselves may need to be cleaned or replaced periodically if they become too damaged or worn to continue use. It is also important that the concrete mix design shows good strength after curing before the light plywood or concrete can be safely removed from its moulding surfaces ensure safety during removal.

The use of forms that are generally able to reveal some element of critical installation through their markings takes full advantage of formwork possibilities; while marking is done mainly to serve as a tool for checking the concrete during the finishing process, it can also serve as an aesthetic element of architectural design. The colour and shape of markings can serve as part of the overall aesthetics of the off-formwork structure itself.

The surface finishes themselves include:

  • Smooth.

  • Rough with sand and/or aggregate included in the finish.

  • Rough with sand and/or aggregate mixed into the cement paste after curing.

  • Embossed by pressing, rolling forms into freshly placed mortar or fresh concrete (sometimes called "wheel marking").

A broom or squeegee can be dragged across wet concrete so as to leave a pattern of ridges perpendicular to the direction of motion; these ridges will become more prominent as precast concrete continues to cure and gain strength for a great final appearance as a result of high quality workmanship. This type of finish is almost always left unpainted unless its appearance forms part of the design concept. Chipped aggregate may also be embedded into freshly placed concrete as it cures, which will become apparent after final finishing has place. For more information about concreting for slab floors, take a look at the Australian Government's Your Home website.