pumpkinstrokemarrow

Pending concrete activity down the bottom of the garden, a concrete dream last night. Now we have a garden shed which is rotting because I built it into the side of a slight hill without taking proper care of waterproofing arrangements, which means that part of the floor and associated parts is rotting. So, from time to time, I ponder about whether to replace it. So last night, I decide that a concrete shed was just the thing. Would take no time at all to knock such a thing up. Plenty of scrap timber in the garage to make the shuttering out of. No need to bother about windows, just make a concrete box. Might be a bit dark but never mind. I don't seem to be concerned about the roof or the door. But then, presumably close to waking and bits of the brain booting up, I start to wonder about how thick the concrete ought to be. Settle for four inches. You can make concrete thinner than this, but not if you are doing it by hand without any mechanical tamping aids. Then start to think. The shed needs to be at least six feet high. Point A, this is more thin concrete than can be cast in-situ in one go. And it has to be in-situ as it would be too heavy to lift single handed. Point B, this is rather a lot of shuttering. Point C, will need scaffolding from which to pour the concrete into the shutter. Point D, we are talking about maybe 12 square metres of wall which amounts to more than a cubic metre of concrete. This is rather a lot of concrete to be knocking up with a shovel in a wooden tray. Still more or less asleep at this point, but now starting to wake up and unravel the whole problem. Maybe a DIY concrete shed is not really the way forward.

But by way of compensation, I do have the buttress to make for the compost bin at the bottom of the garden. The compost bin is made of brick, two sides and a back, maybe 18 inches high. Wooden front and wooden top to keep the rats out and the mice warm. Unfortunately, while the left hand side is properly bonded to the back, the back right hand corner is occupied by a short concrete post and there is no bonding between the right hand side and the back. With the result that the right hand side is now slowly twisting and falling, outwards. Maybe 20 degrees from vertical at the front. So I decided that a concrete buttress is the answer. Would be best in the middle but that is rather awkward, so have settled for the front. Made a neat little shutter for the buttress, maybe a bit less than a cubic foot in volume. Bought three bags of aggregate which I thought was plenty. Started mixing and filling operations, when it rapidly became apparent that my guess of three bags was well out. I should have measured rather than guessed. I should have got more like six bags of aggregate, and a new bag of cement. So the buttress is now going to be in two layers. Hopefully the two layers will bond OK without the aid of any connecting reinforcing bars.

Made the first layer concrete in three mixes, one for each bag. The first dry, probably the right thing at the bottom of the hole. The second rather wetter, probably the result of chucking in half a bag of sand I happened to have lying around and wanted to tidy up, and the third, by accident, very wet. The right mix was probably somewhere between the first and the second mix. Bearing in mind that I was rather short of concrete, had run out of sand and shop aggregate, decided that the way forward was to add more aggregate to the third mix, in the form of gravel from around the bay window to the extension and broken ancient brick, irregular lumps ranging up to a maximum of two inches across. The concrete having aleady been mixed, it had some difficulty wetting the ancient brick, despite being very wet itself, but it probably got there, this difficulty being the reason that one is supposed to mix concrete in one go, without adding things later. I don't suppose this part of the buttress is going to be terribly strong, but hopefully still fit for purpose. And the second layer, if made in a more conventional way will reinforce it a bit.

And then I found that I had forgotten how strong shutters need to be. Wet concrete is heavy stuff and will push one inch screws out of chip board without any problem at all. Poor workmanship, but after the dust has settled I do not suppose anyone other than me will notice. Second layer to be continued when we get our shiny new car back from being made shiny new again after an altercation with a post.