Slab Success!
Haha! It Works!! I made a new slab, this time with bigger stones, and 50% thicker. I went a bit over the top with the thickness, but I wanted to be sure that I wasn’t wasting my time and that it was actually possible to make a dome shaped slab that was (a) unreinforced, (b)less than 100mm thick, and (c) could still hold at least people without breaking.
Also, I put a post up on an online toilet forum (yes, I’m not the only sad g#t on the net trying to make loos!) and a South African guy, who’d made PLENTY of these dome-shaped slabs before (see what he had to say by clicking ‘comments’ below). Anyway, he’s not only provided me with some handy hints and tips and contacts, but has also offered an old fibreglass mould for the dome shaped slab – sweet! This means that me and Siyabonga won’t have to make a mould out of sand every time – and its recycling as well! (my sister and steve will be proud of me!)
Also, I put a post up on an online toilet forum (yes, I’m not the only sad g#t on the net trying to make loos!) and a South African guy, who’d made PLENTY of these dome-shaped slabs before (see what he had to say by clicking ‘comments’ below). Anyway, he’s not only provided me with some handy hints and tips and contacts, but has also offered an old fibreglass mould for the dome shaped slab – sweet! This means that me and Siyabonga won’t have to make a mould out of sand every time – and its recycling as well! (my sister and steve will be proud of me!)
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7 comments:
Dear Gareth
There is an extraordinary amount of material available in South Africa on the construction of VIPs, UD toilets etc. what to do and what not to do.
With regard domed slabs we tried to introduce them about 10 years ago but they never caught on, mainly because engineers did not believe that such slabs (being in compression) did not need reinforcing.
I had a number of glass fibre moulds made, which we used for casting the slab (quality control is easier than on the standard Sanplat) and we used a single piece of wire around the circumference as the tension beam (same as a domed reservoir roof).
I still have one mould on my front step.
Regards
Richard Holden
Hi Richard,
I tested my dome shaped slab today, its a 60mm thick slab and weighs
far too much, but it held the weight of 4 people when supported at 4
points, and I'm going to try with some more people tomorrow. I plan to
make the next one thinner (40mm) and I'll put some steel in it as you
suggested.
This is a bit of a long-shot, but is there any chance that you could
lend me your mould? It would make casting the slab a lot easier!
Thanks
Gareth
Gareth,
You are more than welcome to have the mould. It has been sitting on my front stoep for ages. If you put a line of bricks all around and make sure the slab is evenly supported it will take more than 10 people.
For transporting the slab about the best solution is to rest it on 3 tyres in a trailer or the back of a bakkie. I have transported slabs in this manner over 1,000 km.
You are more than welcome to put my reply on your blog
Regards
Richard Holden
Manager: Science & Technology for Social Impact
Department of Science & Technology
Hello Richard,
Wow, 10 people eh? Brilliant! It would be great to get the mould, I
think I'll be going to Jo'berg soon, so maybe I can make a side trip up to see you in Pretoria?
Thanks for the transportation info too, that’s useful. I just have a
quick question. What do you think about the idea we have of
prefabricating the latrine houses/sheds as flat pack units, and assembling them on site? We want to cut down on the time it takes to build the latrines, and we'd quite like to be able to sell them direct to contractors. Do you think they'll be interested in the idea? Do you foresee any problems? It'd be great to hear what you think.
Thanks
Gareth
Gareth
I live in Joburg so you can pick it up from there.
On the flat pack idea they are doing this in Eastern Cape already. There are also firms that do it on a commercial basis.
David Still has been doing this in Alfred Nzo Municipality and would be able to give you some idea of the challenges posed by this.
One point to take note of is that many of the toilets are filling up and cannot be emptied. Many of them have very small pits so this has occurred in 5 - 7 years. With a brick structure it is impossible (at present) to move them whereas with the old tin toilets they could easily be moved.
Prefab structure have the problem that if one bolt or panel breaks the structure is no longer useable.
Regards
Richard
Richard,
Great, I'll get in touch with you when I can organise some transport
to Jo'berg. What you said about flat pack toilets is interesting too,someone has already beaten us too it then! (not surprising I guess, its not exactly the innovation of the century) still, is there any chance you could put me in touch with David Still, r one of the companies
that are doing it on a commercial basis?
On the subject of emptying, maybe that could be a service to offer
individual customers (i.e. if you buy a new toilet, we'll empty the
old one and fit a new toilet hut/replace the slab if required etc.) Do people often empty their toilet pits, or do they prefer to cover them up and build a new one? Maybe its quite expensive to get a pit
emptied?
Thanks for your input!
Gareth
Gareth,
David Still's details are as follows (for Alfred Nzo)
###contact Gareth for contact details###
Commercial company
Riana Terrblanche
###contact Gareth for contact details###
What people have been doing is digging a new pit and either:
1) Moving the tin superstructure to the new pit; or
2) Building a new toilet.
It is very difficult to empty a pit. To get a vacuum tanker into the rural areas is prohibitively expensive (even if it can get access to the site). In Northern and Eastern Cape trials have taken place with sludge and diaphragm pumps which have proved reasonably successful (The sludge is disposed of on site). Durban have a programme of manually emptying their VIPs and are not building any more. Their choice now is the double pit urine diversion system.
However many pits have been used as rubbish pits making it very difficult to empty them either with a pump or manually.
Regards
Richard Holden
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