Formwork

Sep

2021

Formwork Full Guide: All You Need to Know About it

Formwork refers to the process of making a temporary structure through which concrete can be moulded into the desired share. The method of making this structure includes pouring mixed concrete into the mould that is already in the preferred form. Also, there are two primary forms of formwork, namely the traditional formwork and the modern formwork. On the one hand, the conventional formwork is formed using timber wood or even steel, an alloy. Click here to read more about formwork in Sydney.

Other materials that are useful for traditional formwork are glass fibre reinforced plastic and other high-quality materials. A critical attribute of any material that will fit as a formwork frame is that it must be capable of carrying all the dead and live weight put on it. The formwork will bear any weight that is placed on it. This article is a comprehensive guide on the basic knowledge and application of formwork in modern construction.

Below are the detailed formwork types, their respective advantages and disadvantages, and their importance in general construction projects. Before we dive into the primary style of formwork, we need to give e more detailed description of the significance of formwork in both private and commercial constructions.

Properties of Formwork Materials

Formwork can come in different shapes, materials and containers, including scaffolding, falsework, shuttering, open-box containers in fresh concrete. In all these structures, the process requires pouring and compacting these materials into different desired moulds. The purpose of formwork is not to stand as a permanent structure on the project but to hold the concrete in shape over time.

At the end, when the concrete is fully and permanently set, the formwork can be removed. At that point, a mass of concrete takes the shape of the inner form of the formwork. However, what is the essential properties of the formwork?

Properties of a suitable formwork

Any material that will serve as a formwork must be strong. It must also be able to resist the pressure and weight of concrete on it
The formwork material must be rigid enough to retain the shape of concrete without having to undergo any reformation or deformation
The formwork must not make too huge a difference to the project’s total cost in terms of the cost. Otherwise, it would not be an economically safe decision to include it.
Formwork materials must be watertight enough to avoid any leakage at the joints. Also, the concrete mixture must not soak in water

Types of Formwork

The classification of formwork below is based on the materials from which they are made.

Timber formwork

Formwork that is made of timber is one of the most durable materials in the construction industry. Also, it is usually constructed on the site where wood is imported. However, the timber formwork can be classified in the details below:

Lumber. Lumber refers to a commonly available material with a lot of strength. It also has a relatively higher weight and can cost a bit more as well.
Plywood. The plywood source for formwork helps produce concrete, the formwork with the enhanced quantity of finished concrete.

Advantages of Timber formwork

Timber formwork is easy to cut and trim into the desired shapes
It also has an excellent thermal resistance that can prevent damage to the concrete, primarily when used in cold regions of the world
Timber formwork can also be very light in weight, which makes its use very easy to handle, unlike the other materials
When the timber formwork has fulfilled its purpose, it is the easiest to be dismantled at will

Disadvantages of Timber formwork

One common demerit of using timber as formwork is that it cannot stand the test of time. This material has a somewhat restricted reuse factor.
In addition, if the timber wood is dry, the timber formwork will absorb some moisture from the moist concrete. As a result, the water will weaken the strength of the obtained concrete structure
Excess moisture content in the material leads to a shrinkage of the structure. As a result, the shrinkage can lead to leakage of the grout and the cup open joints of the system.

Steel formwork

Another essential material that can serve in the making of formwork is the use of steel. Steel, as a mixture of metals of outstanding qualities, have several advantages over wood. Although using steel can be relatively costlier than wood, it reimburses for that cost since it can be reused. In other words, using steel may eventually be more economical than timber wood in the long run. The most commonly used steel formworks may contain steel, magnesium and aluminium.

Advantages of Steel formwork

Steel formwork is robust and durable. As a result, it is capable of bearing loads on it
Steel formwork is very easy to fix during construction more than wood
It has an excellent shape on the surface that is smoother than using timber wood
Steel in formwork can be used in great numbers without too many restrictions
The use of steel is a more durable choice than wood formwork
As earlier mentioned, using steel in the formwork is reusable and, therefore, can give a good value for the cost in the long run

Disadvantages of Steel formwork

Using steel for formwork can be more expensive than using wood
Steel in the formwork can lead to excessive weight and therefore can be more challenging to handle than wood
Steel formwork is not easy to manipulate into a different structure. Consequently, it is highly limited in size and shape
Plastic formwork

Formwork can also be made from plastic in a way that produces an impervious surface. This surface also gives a very smooth finish in the final structure and is valuable in private and commercial buildings. Plastic formworks can be reinforced or removed if there be a need. At the same time, the most critical use of plastic is that it is very light and more durable than steel and timber formwork.

Advantages of Plastic formwork

Using plastic formwork produces a very light structure than other formwork types
Plastic formwork is simple to cut and even nailed with the woodwork
It can also be constructive in creating complex structures, shapes and some unique features
It is also easy to remove any damage done to a plastic formwork, unlike other types of formwork

Disadvantages of Plastic formwork

Plastic formwork is relatively costlier than the rest
It cannot bear load as its strength may be small
Plastic formwork is often prone to fire attacks and heat damage

Sep

2021

General Construction of Formwork

A formwork is that impermanent structure that serves as the mould for a concrete mix in a system. The concrete mixture is poured into these formworks to take the desired shape. And when the concrete is set and dry, the formwork is removed. Formwork may be reusable or not. It all depends on several factors. However, this article will focus on the actual process of building formworks for different building projects.

Furthermore, in the construction of formworks, it is crucial to consider the actual purpose of the formwork. For instance, the foundational purpose may be to identify the kind of structure being built. Is it a private structure or a commercial structure that requires formwork? We will take a systematic approach that deals with the core properties of the formwork inside the whole system. The process may include formwork sheeting, bearers, ties, and elements.

The Formwork Sheeting (Formwork Shell)

The formwork sheeting is the mirror image of the components of the concrete that need to be produced. For instance, it comes in direct contact with the existing concrete. Also, it has a molding element in which the formwork begins to have one of the most decisive influences on the quality of concrete surface being used. However, it is crucial the formwork sheeting can resist heavy stress by taking up the surface pressure from the concrete. You can read about Formwork Full Guide: All You Need to Know About it by clicking here.

It carries it off to linear acting supports. And in a formwork pressure distribution, the involved elements include the following

Formwork sheeting
Main bearer
Formwork bearer
Columns
Formwork pressure for the surface pressure as earlier mentioned

A typical formwork sheeting is often part of the initial formwork to wear. The reason is that it often exerts heavy stress and plain concrete with the poured concrete. This construction may also require installing a sheeting material, including sheeting boards and prefabricated wooden panels. At the same time, the formwork sheeting of individual boards may comprise dimensions such as 25 mm thickness and about 140 mm width.

Formwork sheeting boards

Meanwhile, the heartwood side may also lie towards the concrete itself. At the same time, formwork sheeting boards have advantages such as easy workability if you have to plan, see, bore and nail them. On the flip side, they also have the following disadvantages.

The high expenditure of the working time that the boards require are matters of concern when making the formwork
It often has a short service lifespan
It often leads to some loss by the wood that gets wasted

Formwork sheeting panels

Furthermore, one can prefabricate sheeting panels from isolated boards from squared timbers as frames. However, this case is workable when you have to repeat the formwork for the same design, such as the construction of foundation strips. Meanwhile, the prefabrication is done in a workshop while it saves a lot of time on-site while installing the formwork. In other words, prefabricated sheeting panels can help to save that much time on site.

However, sheeting panels are not without some disadvantages in terms of services, similar to the weaknesses we observe in sheeting boards. Ideally, both the sheeting boards and the sheeting panels are used on the site in combination. Now, can we discuss some of the common types of formwork sheeting?

Formwork bearers

The formwork bearers directly support formwork sheeting by carrying off the exerted forces through the falsework structures of all the supporting members, formwork ties and the soil. Also, the formwork bearers consist of squared timbers, while the beam’s cross-section can depend on the loads it bears. In other words, the cross-sections of the formwork beam largely depend on the load it carries.

At the same time, if it achieves good workability, then the wooden beams have a wide field of application. In addition to the wooden beams, you can include prefabricated steel parts such as the clamps and the steel beams. Meanwhile, the clamps are used majorly for the column formwork in the entire structural buildup. A typical steel clamp for column formwork also includes a steel wedge, clamp, and holes for steel wedges.

Formwork ties

In terms of formwork ties, it depends on whether you have vertical or horizontal formwork. For the vertical formwork, the pressure of the formwork acts horizontally according to the stress that it takes up from the two adjacent faces of the formwork ties. The tying is done by slinging a steel wire of about 3.1 mm to 4.2 mm dimension around the formwork bearer’s frame.

You may also have to guide the wires through the boreholes in the formwork sheeting while tightening them through twisting. While doing that twisting, ensure that you maintain the actual width of the formwork for the structure. At the same time, ensure that there are no spaces or holes in the boards of sheets to hold the concrete mix in place before it is set to dry.

Also, you may have to remove the stull (if made of wood) while placing the concrete mix inside the structure for a practical bracing function under pressure. Alternatively, one can brace the formwork steel together by using steel screws into the boreholes.

Elements of Falsework structures

In a brief digression, a falsework structure is the formwork parts that take up the load off the formwork sheeting and bearers. Similarly, the primary functions of the formwork structures are the main bearers and columns. Besides, it has columns that take up the load away from the formwork bearer. When you employ round timber braces, you have an obtainable specially made metal tube adjustable in height. They are also employable as columns in the structure.

When using round timber columns, you may employ double wedges to the foot of the formwork—these structures help to prevent the lowering of the formwork when it is time for stripping to removal. A horizontal arrangement of the falsework elements includes the primary bearers responsible for taking away the load from the formwork away to the columns. The lattice type of metal tube structures can sometimes be employed for huge widths when lacing the columns at close intervals.