Concrete formwork is an easy way to make a concrete slab. This can then be used as a support for a construction, a swimming pool or a terrace, among other examples. To do this, you will need to lay out and assemble planks before pouring your concrete prepared by you or delivered ready to use. Here are our equipment tips and steps to complete your concrete formwork.
How to equip yourself to make a formwork for concrete?
Making formwork for concrete is a relatively simple operation that requires few materials. The formwork is generally made using simple wooden planks, or PVC or aluminum. These three materials are ideal for making a formwork insofar as they are strong enough to support the weight of the concrete and waterproof. Nevertheless, wood is the most common.
The formwork boards available on the market are 2 and 4 meters long, 10 to 30 cm wide and up to 4 cm thick. So choose the boards best suited to your needs knowing that you can cut them if necessary.
You will also need concrete, which you can have delivered ready to lay or which you can prepare yourself by mixing sand, cement and water in a concrete mixer.
To prepare your planks, you will need a jigsaw to cut them to the right length, a drill to join them or, if necessary, a hammer and nails. Also provide oil to apply to the boards to facilitate their removal during stripping. Do not hesitate to plant stakes to clearly delimit the area and keep the boards in place, especially if the surface to be covered is large.
You will also need a shovel and a spade to dig the area, or even, ideally, a mini digger. Finally, a spirit level will allow you to check the flatness of the formwork.
How to make a formwork for concrete?
To make your concrete formwork, you will need to follow the following 4 steps.
Step 1: prepare your surface
You will not be able to lay a concrete formwork without first digging the area. Lay out stakes to clearly delimit it and excavate to a depth of at least 20 cm using a shovel and a spade or, if the surface is large, a mini-shovel.
Step 2: laying the boards
Your boards will allow you to make the formwork easily. Buy them beforehand and choose them in the dimensions that correspond to your needs. Make sure they are strong enough to support the weight of the concrete.
Cut them according to your needs using the jigsaw and assemble them by screwing or nailing them to complete the entire perimeter. Guide yourself from the boundary stakes of the area and arrange your planks in the cleared space. Check their flatness with a spirit level, as the top of the boards will need to match the edge of the concrete slab. If the surface is large, add stakes along the boards to hold them in place and prevent the concrete from breaking, cracking or deforming them.
Finally, once your boards are in place, you can oil their interior surface. It will then be easier to remove them when the slab is dry.
Step 3: pour your concrete slab
The concrete mixer is practical for preparing your own concrete by mixing sand, gravel and cement. It is possible to rent one for several hours or several days if you do not have one. You can also opt for direct delivery of ready-to-lay concrete by means of a mixer truck. The latter solution is only advantageous for large areas, because delivery is expensive. It is therefore better that it is profitable.
Your formwork in place, you just need to pour your concrete into it. With a stick or a stake, prick it in places to ventilate it well.
With a trowel, smooth the surface of the slab and then let it dry without touching it. A small slab needs 2 to 4 days to be perfectly dry. For a thicker slab, count 7 to 10 days. Be careful not to walk on the slab until it is completely dry.
Step 4: remove your formwork
When the slab is completely dry, it is time to strip it. With a small hammer, tap the sides of the form boards to loosen them from the concrete. If they have been well oiled, their removal will be easier.
Be careful, however, to measure your movements carefully so as not to damage the slab. Concrete is indeed a friable material and its edges are fragile.
You can now affix a construction to your concrete slab (garden shed, swimming pool, garage, lean-to, carport, etc.) or cover it with a coating of your choice to make it a terrace, a pool deck, etc.