For some time now I’ve been looking for ways to make my modern war/Post Apocalypse scenery look more realistic. I’ve wanted to give reinforced concrete a go for some time and so recently decided it was time to make some. Unfortunately while this has turned out to be an easy technique it has taken my four failed attempts to get it right (I won’t say what they were as looking back they were obvious mistakes). Anyway if you want to spice up your scenery a little here’s one to try.
Lets Get Started
First thing you are going to meed is a plastic clam shell case (larger is better) and some paper clips (lots). The lid of the clam shell case is going to be my casting mould so I’ve cut this off, I’ll use the body of the case to mix my plaster later.
For my reinforcing bars I’ve straightened out some paper clips (lots of paper clips). Luckily for me they almost exactly the same length as the width of clam shell case I’m using (pure luck, honest). Once you have enough of these lay them out in a grid patters and superglue them together (first attempt I didn’t do this and the plaster set before I could get them all in place). You don’t need to glue every join, just enough to hold it loosely together if you handle it with care.
Next glue some matches into your mould tray. These need to be enough to lift your mesh away from the bottom of the tray to roughly the half height of the plaster. If you don’t do this the mesh simply sinks to the bottom of the plaster (as I found out the hard way).
Now it’s time for the casting. I’m using Herculite for mine, partly because it is a very strong plaster but mostly because I have a big tub of in the garage (always buy this sort of stuff in bulk, it’s cheaper and will stay usable as long as the container is properly sealed). I poured the plaster into the tray to the level of the supports (matches) and then dropped my reinforcing bars into place. A quick top up with the plaster and level off with a wooden drinks stirrer (you should have a supply of these by now if you try any of my techniques).
At this point it’s a good idea to have a cat handy to pass the time while the plaster dries or you could use some paper towel to clean up some of the mess. Herculite takes about 15 minutes to become firm and about half an hour to be strong enough to demould safely.
Once the plaster was dry enough to handle I removed it from the tray and put it in the airing cupboard for 2 days to fully dry. You can tell when it’s dry as it does white rather than the creamy colour it was just after it was made.
The Final Breakup
Now Herculite is great stuff, it’s has fine detail, it’s light, it dries fast and it is very strong, even before you add reinforcing bars to it. Adding reinforcement just makes it – Stronger! Snapping away the ends along the weak point where the matches were and there is no reinforcement wasn’t too bad, breaking the reinforced section was another matter.
First I tried a hammer but with little success. Eventually I found that a combination of hammers, chisels, screw drivers, gouges and swearing will break up the plaster in a very natural way. I was going to break this up further but have decided to use it as a 1st floor for a bombed out building instead. And of course don’t throw away the rubble that’s left over.