On this site there's been a lot of discussion over building materials, and how you might not have enough time to build your fort when Z-Day hits.

The solution? Concrete solutions.

Concrete itself is extremely cheap, and goes hard in 4 hours, setting completely in 24 hours. Reinforced concrete is simply concrete with steel (or any metal) grids sunk into it, allowing it to take pressure without snapping.

At 1 metre (3 feet) thick, concrete can stop most bullets (even .50 cal rounds, I think) and small explosions. And at 4m high, it's enough to keep the zombies out permanently.

However, to make your concrete paradise you need foundations. A wall would need a 0.5 metre foundation, which means you'd have to clear 0.5 meters of ground deep before you could pour the concrete. So, a 4 metre wall would actually be 4.5 metres high, with the foundations.

To make this wall, you need something to keep the wet concrete there until it sets. That's where FormPly comes into the equation. FormPly is a non-stick plywood, that is used to make 'moulds' for the concrete, and is removed once the concrete sets. In the Google Sketchup diagrams below I'm going to demonstrate how this works.


1. Mark out where the concrete will be placed. In this diagram, this section of wall will be 5 metres long, 1 metre thick, and 4 metres high. The man is 2 metres tall.





2. Your next step will be to clear 0.5 metres of ground where you wish to place the concrete.

All concrete structures require foundations. This is when the concrete structure is secured by the ground, and allows it to take weight. For a one-storey building, the foundations must be at least half a metre deep.




3. FormPly normally comes in 1.5x2 metre sheets, so you're going to have to cut and join the sheets of FormPly to whatever size is required. You will need to end up with four pieces of FormPly, according to the size of the concrete block you want. Once you have, use them to form a box, like in this example. The front has been made transparent in this diagram, so you can see the inside.

In this example, the FormPly only goes down to the ground, and not into the foundation. This way, when the concrete is poured, it will be shaped so that it fits the dirt perfectly, giving it more support as there will be no gaps between the concrete and the dirt. So, it would need two 5x4 metre sheets, and two 1x4 metre sheets.

Also, temporary reinforcing will be required to hold the box together, as the weight of the concrete will exert outward-pushing pressure. As it is unlikely that you will be able to acquire professional tools to do this, you will need to improvise - debris can be utilised for this purpose.




4. Once this is all done, the concrete is poured into the mould. While concrete takes 24 hours to fully set, it goes hard after 4 hours. If you wish to make reinforced concrete, you must sink the iron gridding into the concrete before the first 4 hours, and support the rebar until the concrete sets.

The concrete must be kept safe from the weather, so a simple tarp over the top will keep the weather out until it sets. After 24 hours, the FormPly can be taken away, and there you have it - a reinforced 1 metre thick concrete wall!





Using this technique, you can build multiple blocks like this, all up next to each other. You can fill the small gaps (5mm at the most) with silicone sealant. However, you might not want a wall that high, because it takes too much concrete. It's up to you - now go forth and build!