Column formwork is a mandatory procedure that is performed before installing a rectangular pillar. Without it, the installation may be inaccurate and result in the column not being level enough. Below we will tell you about what columns are and about the phased method of their formwork.
With the help of formworks, column parameters are formed. Structural differences in the final result are determined by the type of work carried out. In some cases, formwork is installed for columns of a certain size, and sometimes for universal ones. Depending on the size of the element, care should be taken to use a sufficient number of additional shields.
It is important to remember that for universal formwork, panels with clearances for the kingpin (5 cm per step) are required. In the case of a fixed installation, the column is fixed using corner elements (the number depends on the number of faces on the future structure).
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Regardless of whether the columns perform decorative functions or serve as supports, they are divided by shape and appearance into:
In the framework of one project, columns of any one form are most often used.
Column formwork is needed when you need to create a support around a building element. It is obvious that it is almost impossible to do this without backup. In addition, such molding helps to create the necessary geometry: square, oval, etc.
In order for the column formwork procedure to proceed correctly and give a good result, a number of requirements must be observed:
The slightest deviation from the dimension will lead to a lower strength of the final building.
If the product is installed crookedly at an angle or unevenly centered, then this will negatively affect the reliability of the construction and, from a technical point of view, will be considered incorrect.
In order for the casting to be successful, it is necessary that the concrete completely fills the formwork. If it is installed incorrectly, the mixture will begin to flow out, thus creating cavities and unevenly covering the area of product.
Since the formwork must eventually be dismantled, it is very important to pour it so that the concrete does not grab parts of the structure. If the mold is removed with excessive force, it can lead to cracks and chips.
Even violation of one of these points can lead to the fact that the column will undergo critical destruction and deformation.
Based on the possibilities and needs, three types of molds are used in construction: disposable, reusable and non-removable. Each of them has its own characteristics and advantages.
Single-use formworks most often used in the installation of small elements, as well as in private construction, when it is more economically justified. It is a special water-repellent thick cardboard. Due to its properties, it does not absorb the mixture and therefore can be easily removed after the concrete has hardened.
The diameter of this form can be from 15 to 120 cm, and their length reaches 10 or more meters. In accordance with its dimensions, the wall thickness will also change, the calculation of which depends on the volume of concrete inside the formwork. Installation of such molding is quite simple and does not require any special skills.
Reusable formwork is already being used more typically in large facilities and in commercial construction. These molds can be placed and dismantled many times. Installation of this design requires certain skills, since here it is necessary to carefully adjust the size and height. In addition, in different cases, it is necessary to choose the right type of reusable formwork. They are:
Shapes to create square or rectangular columns. These are metal sheets, mostly without seams, on the inner surface of which laminated lumber is placed and clamped until the desired dimensions of the future product are reached.
Multi-component constructions for creating both large and complex building elements, and for private use.
Used for molding, including round columns. In this case, the concrete is in contact with the surface of the sheets, so it is necessary that they be lubricated with a special solution and completely cleaned.
Perform the same functions as steel or panel formwork, but have less strength and reliability of the seams.
Fixed formwork is also quite popular under certain circumstances. This is a thin material construction that allows pouring columns. Due to the strength of the form itself, you can get a reliable, but not too bulky building element.
In order for the column to meet the technical characteristics required for its operation, you should carefully approach their installation step by step:
The solution should be poured based on the structure of the formwork. In small structures, this can be done from above, and in larger ones, the so-called windows are designed for this. They are a shield that is removed, concrete is poured into the hole, after which the opening is closed back.
Beam-transom formwork can be a rather complex structure, consisting of many elements. Since its dimensions can be very impressive, so as not to unnecessarily burden the process, this form is made mainly of wood. This simplifies its installation, thanks to which, with the help of beam-transom formwork, concreting of columns of various sizes is carried out, and within the same project. To create and strengthen it, you only need a couple of tools that any builder has.
With its help, it is easy to carry out the construction of various geometric elements, including round, cylindrical, oval, without buying special blanks for this.
To implement beam-transom formwork, you should:
It is necessary to create the formwork with high quality and the first time, since this is not a procedure that can be redone in the event of an unsuccessful outcome of pouring concrete. Therefore, we recommend that you enlist the support of specialized equipment, as well as carefully study all the accompanying documentation and follow it exactly.
On the right we have a shot of concrete formwork for a column. Just behind it we see a column that is completed, with it's cranked starter bars sticking out of the top, ready to connect to the next stage, the suspended floor slab.
The finished column would have been left in it's concrete formwork for a day or so, then stripped and the clear plastic immediately wrapped around it to stop it drying out too quickly. This is known as curing the concrete. More on concrete curing here.
The footings are poured in the ground, and starter bars will be coming out of the footing, and the column rebar steel will be fixed the them.
The carpenter makes up two pairs of formwork shutters or forms, and nails them in place around the rebar steel.
He has already shot pieces of timber onto the footing concrete to allow him to locate the concrete formwork in the correct place. You can see one at the bottom left of the close up photo.
He then bangs in 75mm nails to hold up the column clamps until he has them assembled and just nipped up. The photo shows the column clamps which come in different lengths. A clamp set consists of four lengths of 75 x 8 steel with a hook on one end and overlapping slots in the other end, to take the steel wedges that do the work.
Column Formwork - Acrow metal column clampsYou can see that the clamps are positioned alternately up the column, So that the wedging force changes direction with each clamp. If they were fixed all the same way, there would be a tendency to put a twist in the column.
The props used are the industry norm "Acrow" type props. Which come in varying lengths.
The props have large and small holes at the top and bottom for connecting to other fittings, and nailing the props to sole plates, at the bottom and bearers etc. at the top. Steel props like these were designed for concrete formwork, but have found there way into many other applications because of their versatility.
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There is a requirement in the standards for concrete formwork and concrete codes, that mixed concrete should not be allowed to fall freely over a certain distance. The reason for this is that the concrete ingredients tend to segregate when they fall.
The columns in this picture would have had to have a removable window in the forms, say half way up, that is used to fill the lower half of the form, then the window is put back in place and usually wedged, then the rest is filled.
It is not often done these days , because of the use of concrete pumps that allow the last section of the delivery pipe to be lowered into the column and brought slowly out, as the concrete rises. Also the mix of the concrete is designed differently for pump use.
The same thing applies to walls of course. I can remember putting windows half way up some walls that were tapered, thinner at the top. The pump delivery pipe did not have enough room, because of the reo steel, to get down the inside of the form without a risk of getting it stuck.
If you are doing small slow pours, say mixing on site, in high forms, use windows. Apart from the segregation issue, the concrete as it falls from the top sticks to the sides of the form and rebar, and can have already taken on it's initial set before you add the rest. This later gives a flaky surface to the finished concrete.
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Here is a method that was used before steel column clamps came on the scene. At least where I was. It is easy to make up a few sets of of these.
You may say why bother showing something that is obsolete? Well plenty parts of the world still work with home made stuff, and I say "good on em". More to the point though, this method can be used for one off column or larger boxes. It can even be used around a one off beam where no other formwork is needed on the job.
Left is a sketch of the wedges from the side. The wedges are put as close to the ends of the bolts as possible, otherwise the bolts could bend under pressure.
Note! Clamping the forms together can push the forms in too far if you do not lay out the ply and battens as detailed. There must always be a firm edge to push up to. (desirable with most formwork actually).
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Column formwork is a mandatory procedure that is performed before installing a rectangular pillar. Without it, the installation may be inaccurate and result in the column not being level enough. Below we will tell you about what columns are and about the phased method of their formwork.
With the help of formworks, column parameters are formed. Structural differences in the final result are determined by the type of work carried out. In some cases, formwork is installed for columns of a certain size, and sometimes for universal ones. Depending on the size of the element, care should be taken to use a sufficient number of additional shields.
It is important to remember that for universal formwork, panels with clearances for the kingpin (5 cm per step) are required. In the case of a fixed installation, the column is fixed using corner elements (the number depends on the number of faces on the future structure).
Regardless of whether the columns perform decorative functions or serve as supports, they are divided by shape and appearance into:
In the framework of one project, columns of any one form are most often used.
Column formwork is needed when you need to create a support around a building element. It is obvious that it is almost impossible to do this without backup. In addition, such molding helps to create the necessary geometry: square, oval, etc.
In order for the column formworkcolumn formwork procedure to proceed correctly and give a good result, a number of requirements must be observed:
The slightest deviation from the dimension will lead to a lower strength of the final building.
If the product is installed crookedly at an angle or unevenly centered, then this will negatively affect the reliability of the construction and, from a technical point of view, will be considered incorrect.
In order for the casting to be successful, it is necessary that the concrete completely fills the formwork. If it is installed incorrectly, the mixture will begin to flow out, thus creating cavities and unevenly covering the area of product.
Since the formwork must eventually be dismantled, it is very important to pour it so that the concrete does not grab parts of the structure. If the mold is removed with excessive force, it can lead to cracks and chips.
Even violation of one of these points can lead to the fact that the column will undergo critical destruction and deformation.
Based on the possibilities and needs, three types of molds are used in construction: disposable, reusable and non-removable. Each of them has its own characteristics and advantages.
Single-use formworks most often used in the installation of small elements, as well as in private construction, when it is more economically justified. It is a special water-repellent thick cardboard. Due to its properties, it does not absorb the mixture and therefore can be easily removed after the concrete has hardened.
The diameter of this form can be from 15 to 120 cm, and their length reaches 10 or more meters. In accordance with its dimensions, the wall thickness will also change, the calculation of which depends on the volume of concrete inside the formwork. Installation of such molding is quite simple and does not require any special skills.
Reusable formwork is already being used more typically in large facilities and in commercial construction. These molds can be placed and dismantled many times. Installation of this design requires certain skills, since here it is necessary to carefully adjust the size and height. In addition, in different cases, it is necessary to choose the right type of reusable formwork. They are:
Shapes to create square or rectangular columns. These are metal sheets, mostly without seams, on the inner surface of which laminated lumber is placed and clamped until the desired dimensions of the future product are reached.
Multi-component constructions for creating both large and complex building elements, and for private use.
Used for molding, including round columns. In this case, the concrete is in contact with the surface of the sheets, so it is necessary that they be lubricated with a special solution and completely cleaned.
Perform the same functions as steel or panel formwork, but have less strength and reliability of the seams.
Fixed formwork is also quite popular under certain circumstances. This is a thin material construction that allows pouring columns. Due to the strength of the form itself, you can get a reliable, but not too bulky building element.
In order for the column to meet the technical characteristics required for its operation, you should carefully approach their installation step by step:
The solution should be poured based on the structure of the formwork. In small structures, this can be done from above, and in larger ones, the so-called windows are designed for this. They are a shield that is removed, concrete is poured into the hole, after which the opening is closed back.
Beam-transom formwork can be a rather complex structure, consisting of many elements. Since its dimensions can be very impressive, so as not to unnecessarily burden the process, this form is made mainly of wood. This simplifies its installation, thanks to which, with the help of beam-transom formwork, concreting of columns of various sizes is carried out, and within the same project. To create and strengthen it, you only need a couple of tools that any builder has.
With its help, it is easy to carry out the construction of various geometric elements, including round, cylindrical, oval, without buying special blanks for this.
To implement beam-transom formwork, you should:
It is necessary to create the formwork with high quality and the first time, since this is not a procedure that can be redone in the event of an unsuccessful outcome of pouring concrete. Therefore, we recommend that you enlist the support of specialized equipment, as well as carefully study all the accompanying documentation and follow it exactly.