how ´bout a drop to drink?
|Water can be a blessing and a curse. After a couple
years of draught, the skys opened (1995) in
Moshi,Tanzania and the roads were impassable.
The same rains can be a blessing as relatively clean water delivered straight to your home.
|Or, in the case below, a school, Iluhya Sec. School in Northwestern Tanzania. There were a number of discarded leaky galvanized watertanks hiding in the grass around the school. By simply making one lengthwise cut in the one that was in best shape, then resecuring with some self-tapping screws and metal strips, it could be used as a form for making ferrocement tanks thet were longer than itself. (Maybe it was stretched outward some, to make it easier to remove.) Ferrocement is sand-cement mortar reinforced with chicken wire and can make strong, though thin walled, structures (even boats).|
|The tank-form was placed on the old watertank foundation. It was lightly oiled with spill-oil then covered with one layer of chicken wire. The chicken wire extended a bit above the form to help form a joint with the extension upward to be made later. One strand of soft 3mm iron wire was tightened into every other corrugation.|
|Then it was ready to be covered with just enough (as DRY as workable) sand-cement mortar to fill the corrugations plus about 1cm. (The walls were about 5-6 cm thick when finished.) Very important, after applying the mortar, was to keep the mortar as WET as possible, at least to prevent it from drying as the cement hardens while binding water. In the picture below can be seen the tin and plastic used to protect the cement from drying. But it still had to be splashed several times a day.|
|After about 3-5 days (I think) the tank was firm enough (it felt hard) to remove the corrugated form. By removing the screws holding the one seam together, we were able to pull the one side in and "behind" the other. By overlapping we were able to decrease the diameter enough (about 8-10cm) to get the form to be able to go free from the corrugations and be lifted out. After scrubbing the "corrugated" inside of the ferrocement wall, we filled the corrugations with sand-cement mortar from the floor up to 2-3 corrugations from the top. The top corrugations were left so we could re-install the form in a higher position so we could continue up another meter.|
|Then the procedure was repeated. The form was removed
and could be used to make the next tank. We also made a
low conical ferrocement roof on the ground.
We weren't able to get it up without cracking it. But with some wooden props inside and more mortar, it became quite sturdy.
If a ferrocement tank like this one were to be give an upper section like another tank in this site, the walls might need to be reinforced perhaps with 3-4 half-brick columns along the (inner?) perimeter.
Index page © Jeff Forssell wat-afr.htm Last uppdate 2000-Aug-1