As an Architectural engineering student I learn a lot about building with concrete. The funny thing is that I never used concrete in my life. So I was going to change that and make something out of concrete. The first thing I came up with was a concrete garden bench. So here we go!
If you like this project please vote for me in the concrete contest.
Step 1: Materials and tools
- Melamine Board or shuttering plywood:
To make your mold you need a waterproof plywood with a smooth surface. Shuttering plywood is a material that's designed to make molds. It's got a very smooth surface and is water resistant. It's also very expensive. When you are planning on reusing the mold I will recommend shuttering plywood. Otherwise melamine board is a cheap alternative.
Melamine board got a smooth surface but it isn't water resistant at the sides. I found an old closet in the dumpster and used these boards to construct my mold.
I used 10 premixed concrete bags (25kg each). The premixed bags are easy to use. When you want to make your own concrete you have to put the cement, sand and gravel together. 1 part cement, 2 parts sand and 3 parts gravel. When you change the size of the bench you have to calculate the amount of concrete you need. A 25kg bag of concrete is good for 12 liters.
- Silicon sealant
- Release agent: silicone spray, petroleum jelly, WD40, etc.
- Masking tape
- Some pieces of scrap wood
- Concrete coloring (optional)
- Power drill
- Chaulking gun
- Old orbital sander
- Mixing bucket
Step 2: Making the mold
The cutting of the pieces was done by my local hardware store. When everything fits correctly it's really easy to screw together.
The cutout was made with a circular saw. Place the two sidepieces on top of each other and clamp them down before cutting. Doing this you will get two identical pieces.
You can now screw everything together. Be sure to use a lot of screws because it has to withstand the pressure of the concrete.