Commercial ready-made concrete strip edges are readily available, but they are a fairly large investment and often require a lot. You will make great savings by making them yourself. Wood is the best material for making these molds. Here we used fir, presented in the form of planks and cleats. The shape chosen depends directly on the thickness that one wants to give to the border. The small thickness that we retained here involves a reinforcement of the concrete.
- Fir planks
- CTBX plywood
- Formwork oil
- Concrete irons
- Mold making
- Pouring concrete
1. Each mold is composed of cleats limiting the base and sides of the border, and a piece of board cut to form the hoops.
Draw an integer number of semicircles between two parallel lines, then another line between these two lines, intended to "break" the acute angles formed by the meeting of semicircles.
2. When the tracing is complete, cut the rounds with the jigsaw following the outside of the tracing. Do not over force the blade in curves.
3. Lay the mussels flat on a regular, hard and clean surface. If you want to reuse these molds, you will want to put them on a plywood panel of "marine" quality (label C.T.B.X.) resistant to moisture. Otherwise, it is possible for you (as here) to paint the panel to protect it.
4. The molds must be perfectly fixed on their support. To do this, simply nail them securely to the panel, without completely driving the nails, so that they can easily be torn off during demolding. Pay special attention to the good connection of the elements between them, because the mold must be waterproof. For this, preferably use planed wood, including on the edges. On the same panel, you will be interested in placing several molds that will allow you to cast several borders in series.
5. Before pouring the concrete, it is essential to oil the molds to facilitate demolding. You can use ordinary mineral or vegetable oil, but you will find in the trade special oil called "formwork" that does not stain the concrete after demolding. Extend the oil with a brush, particularly insisting on the angles where the risk of snagging is greatest.
1. Given the lack of effort and load on the curbs, the concrete you will use may be very light and have a small proportion of gravel. At the limit, it is even possible to use only mortar (cement + sand). You will easily find ready-to-use mortar, sold in small quantities (1 to 5 kg packaging). It is not actually a real pouring, the concrete here has been spoiled quite thick. As the mold is shallow, concrete can be trowelled.
2. Given the small thickness of the edges, it is obvious that this results in a significant fragility; you have to do a reinforcement. Indeed, the edges could break during transport or placement. Drop straight irons crossing at right angles. We used here 5 mm diameter drawn iron, and 10 mm diameter smooth irons. It is not essential to tie the irons between them, the casting being done well flat.
3. You must cover the rebars. Lay a second layer of concrete still with a trowel. Make it penetrate well between the irons by giving parallel blows of the end of the trowel. Be careful not to move the irons if they have not been ligated!
4. It is very important that the embroidery is crisp. For this, you will have to smooth the concrete before demolding. Work on the trowel.
5. For a neat finish, you can smooth all the elements with a damp sponge.
6. When the concrete is dry, you can proceed with demolding. Work slowly so as not to damage the border.
(photos / visuals: © DIY-Prod, except special mention)
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