the loo factory

Signing off...

noreply@blogger.com (Gareth) — Tue, 15 May 2007 12:02:00 +0000

Although I should probably have mentioned it earlier, I’ve left South Africa now, and I’m back in the UK, designing buildings in London. I’m continuing my involvement in Engineers Without Borders-UK, and there is another volunteer who is due to arrive in South Africa to continue the ‘loo factory’ project (and hopefully this blog too!) Thanks for everyone who’s read the blog!

The Cemforce Slab

noreply@blogger.com (Gareth) — Thu, 08 Feb 2007 21:11:00 +0000

The Cemforce slab is made up of the same sandwich material used for the panels, but with some steel reinforcement cast in the bottom half of the mould, to increase the bending strength of the slab. Wicus, one of the owners of Cemforce, carried out a pretty impressive test on the slab, which is only 65mm thick, by supporting the slab on two supports and slowly adding bags of cement across the middle. With 900kg of cement on the slab, it only deflected by 5mm!

In rural areas, when a toilet pit fills up, they are rarely emptied, since this requires a tanker to come and suck the c##p up, which costs money. Instead people tend to dig a new pit and install a whole new toilet. Cemforce had designed a cool little buggy thing which is bolted together around the edge of the slab. The frame and the slab is then lifted up using a big lever, and wheels are fitted onto little brackets at the corner of the buggy. It can then be wheeled over the new pit and lowered into position, and the buggy frame removed. This way people don’t have to buy a new toilet every time the pit fills up… (as long as they can call up cemforce to get hold of one of those buggies)

Cemforce's Ingredients

noreply@blogger.com (Gareth) — Thu, 08 Feb 2007 20:59:00 +0000

Well, to my perhaps more-than-slight disappointment, the ingredients Cemforce used were different to what I was using. For a start, they are using a Cement:Sand ratio of 1:1, whilst I was using 3:1, which means they are using 3 times more cement in their mix than I was. Like me they add a plasticizer to the mix to reduce the water content, whilst at the same time making the concrete runny enough to spray it into the mould, but they also add an accelerator, which allows the concrete to cure faster.

For the reinforcement, they use alkali-resistant glass fibre rather than polypropylene, as they found that the polypropylene tended to stretch before reaching its full tensile capacity, during which time the concrete began to crack (I have some glass fibre mesh, but haven’t got round to testing it yet). The fibres are chopped, rather than woven, cos its cheaper that way, and they can be sprayed into the mould, rather than having to be placed by hand (see the the video below).

The Cemforce loo

noreply@blogger.com (Gareth) — Wed, 24 Jan 2007 13:42:00 +0000

Cemforce are using a panel made up of a mix of 28mm concrete and polystyrene mix sandwiched between two layers of Glass Fibres mixed with concrete, as you can see below.
These panels are then assembled into latrines. Their factory in Kimberley is semi-automated, and has about 120 production workers, producing, an average of 4000 loos per month. They sell complete units, including the pit lining, toilet slab, and toilet house, to Contractors who have won government contracts to build latrines for the poor.

Here's a little video of one of the early stages of the panel production line:

A layer of wet concrete is sprayed onto the mould, then a mix of wet concrete and glass fibres is sprayed on. This produces the first Glass reinforced Concrete layer. The next stage of the production process is that a layer of polystyrene and concrete mix is packed in by hand, and then another glass reinforced Concrete layer added.

It was pretty cool to see the factory in action. It wasn't a huge place, and it seemed like it was something that Esibayeni could handle. Wicus was happy to give us plenty of info, and I almost broke my pen trying to scrobble down all the stuff he was telling us!

Visiting an Actual Loo Factory!!

noreply@blogger.com (Gareth) — Wed, 24 Jan 2007 13:02:00 +0000

I contacted Wicus at Cemforce, and explained what I'd been up to since I arrived in South Africa. He very kindly invited me down to Kimberley to check out the factory and see what he’s been up to.
I was pretty excited at this point :-) If Esibayeni could partner with a company that were already producing loos, then it might be possible for them to get someone experienced to assist Esibayeni with setting up a factory, reducing the risk associated with setting up the factory.
This would be quite a nice way for me to end my placement, since I am returning to the UK in a few weeks, and after visiting the factory Esibayeni would be in a good position to decide either carry the project forward in a big way, or see the factory and decide that its too much to take on.
So... I asked Andre, who helps run Esibayeni, and he agreed to come down to see the factory! Hurrah!

The drive to Kimbeley, in the Northern Cape province of South Africa, took 11 hous each way (and Andre insisted on driving the whole way, he must be mad!) Anyway as well as the glamorous claim to being home to a prefab latrine factory, Kimberley is the birthplace of the De Beers Diamond mining company, which was started up by Cecil Rhodes and his cronies. There are lots of Diamond mines in Kimberley, including the Big Hole, which is completely hand-dug until it closed in 1914 and is absolutely massive...I'll save you the stats :-)

Cemforce. Our New Best Friend!

noreply@blogger.com (Gareth) — Wed, 24 Jan 2007 12:36:00 +0000

Dave Still, who works for Partners In Development, a South African Engineering firm who reached me through the sanitation online forum ecosan put me in touch with Wicus at a company in Kimberley known as Cemforce, as they were producing prefabricated loos doing something similar to what we were aiming for. Cemforce had started off with housing, moved into latrine production, and had recently gone back into housing, with 5 prototype houses using the same panels used for the toilets.

This all sounded pretty familiar! I was originally sent by EWB-UK to South Africa to work with an NGO called Esibayeni on a low-cost housing project. When I arrived I found that the project was still just on paper. Since we were starting from scratch, I thought that it would be a good idea to concentrate on trying to build latrines first, which would be much easier, and give us some experience of the manufacturing a construction material before moving onto housing. I was pretty encouraged by the fact that Cemforce had gone along the same lines.

In Other News...

noreply@blogger.com (Gareth) — Mon, 04 Dec 2006 16:51:00 +0000

One of the other projects we’re working on is a water supply project for our local Municipal Council. We advertised for Engineers to do the design work, and now me, Tim and Hattie, the other EWB-UK volunteers (with a bit of help outside) are helping to ajudicating the tenders. Here’s a little blarb that I wrote for a newsletter about the project.

Strengthening

noreply@blogger.com (Gareth) — Mon, 04 Dec 2006 16:38:00 +0000

I was in touch with the producer of my cement and was sent some lovely Cement performance curves!!
Buildcrete curve (general purpose cement)
Powercrete curve (a slightly quicker-setting cement)
Duracast curve (an even quicker setting cement)

These little beauties opened my eyes a little.

I knew that less water=stronger cement (see earlier post) but I didn’t realise the extent to which this mattered. For every 1 L of cement, I’m putting in 0.8L of water, so that its runny enough to work with. This is because I’m using fine sand, as well as coarse sand. This fine stuff is good because it fills voids between the coarser sand, but is bad because it is very thirsty; you need a lot of water when you use it..

So… I’m gonna reduce the fine sand content a bit. Although in one respect it will make the concrete panels weaker, I think this will be more than outweighed by the benefit of having to use less water.

Fingers Crossed!

SHOW ME THE MONEY!!!

noreply@blogger.com (Gareth) — Mon, 04 Dec 2006 16:29:00 +0000

Over the past couple of months, poor Gareth has been having to cough up some of his own money to buy bits and pieces to continue the development work :-( sniff...
So I said to Esibayeni (the organisation I’m working for). “I’ve got no money, you’ve got no money. We need money”.
And so they got on the phone and wrote a funding proposal to a South African Investment Fund and the World Bank for a seed grant so that we have enough money to get the project to the point where we can build a prototype. Anyway, the South African guys seem keen and are sending someone to interview us, so fingers crossed! This would mean we have enough money for supplies and equipment, and enough to pay for me to stay until the end of March. Great!

Time to Raid the Bottle Bank...

noreply@blogger.com (Gareth) — Mon, 04 Dec 2006 16:25:00 +0000

My panels are floppy. Its sad but true. They need to be stiffer!
I visited a Textile Concrete factory where they use Textile Concrete to make all sorts of pretty concrete products, including doors, wall panels, and even artwork and sculptures. The textile gives the concrete enough extra strength to be able to sculpt the cement mortar, do you ever remember making papier mache sculptures out of wire mesh? It’s a bit like that.
They were understandably reluctant to reveal their commercial secrets, but we did find that they’d used Glass Fibre mesh to strengthen their Textile Concrete panels.

Since then I’ve got hold of a roll of Glass Fibre mesh from Durban. Fingers crossed it’ll help with the stiffness.

Also I thought hey – woven glass fibre mesh might have some recycled glass in it right? Well apparently not. The mesh manufacturers put me onto the Glass Suppliers. A very helpful bloke told me that their fibreglass insulation is made up of glass fibre with up to 40% recycled content, but fibreglass used for reinforcing mesh must be of a higher quality (no organic material) and so is made using virgin glass. Bummer.

Slab Success!

noreply@blogger.com (Gareth) — Mon, 04 Dec 2006 16:21:00 +0000

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!)

Making Cement More Green and Fluffy

noreply@blogger.com (Gareth) — Mon, 04 Dec 2006 16:13:00 +0000

I like recycling, I think it’s a great idea. So I thought that I should look into how I could use recycled materials in my work.

I’ve heard lots of people mention Fly Ash as an additive to cement. Fly ash, (AKA Pulverised Fuel Ash or Blast Furnace Slag) is the stuff left over after burning coal. You can use it as a replacement for some of the Cement you use for concrete. Great eh? I spoke to a big cement producer in South Africa and they told me that the cement I was using already had 20% Fly Ash in it (apparently they caught onto this quite a long time ago) and soon they’d be producing cement with 40% Fly Ash in it. Hurrah! I was being recycling(ish) without even knowing it!

Pontus said...

noreply@blogger.com (Gareth) — Wed, 15 Nov 2006 07:19:00 +0000

Sometimes I wake up in the middle of the night and think to myself: 'thank god I'm not an engineer'.
Then I go back to sleep. =)

[Brilliant]

Engineers Without Borders Blogs

noreply@blogger.com (Gareth) — Mon, 13 Nov 2006 17:24:00 +0000

I've been sent to South Africa as a volunteer with Engineers Without Borders-UK (EWB-UK) and I've just stumbled on some more EWB volunteer blogs which you might be interested in...
Building Wind Turbines in the Philippines
You've gotta check this one out cos he's working with SIBAT, who I voluntered with as a VSO volunteer 2 years ago - There's even a photo of the first wind turbine that I helped to build and paint!
Havana Water Project
Eco-Sanitation in India
Working with Farmers in Zambia
This one is a bit old though.
Working with Farmers in Ghana
A token EWB-USA blog
From Womens Development to pasteurising tomatoes!
A couple of blogs from EWB-Canada
A US Peace Corps Volunteer setting up a computer centre in Togo

Technorati blog directory

noreply@blogger.com (Gareth) — Fri, 10 Nov 2006 10:40:00 +0000

Technorati Profile

The Case of The Missing Concrete

noreply@blogger.com (Gareth) — Fri, 10 Nov 2006 10:17:00 +0000

When I began making up my Concrete mix, I used a Cement:Aggregate ratio of 1:3 by VOLUME, then added enough water to make the mixture as runny as I wanted. For example, I used 4L cement and 12L of sand, and 4.2L of water. Which I assumed would give me 4+12+4.2=18.2L of concrete.

Big mistake!

The finished test panel seemed quite thin, so I measured the ACTUAL volume of mix that I had made up. To my surprise I found that I had only 12L of concrete!? I had lost 6.2L of Concrete! Then I had a think...(never a good thing)

Between the Cement and Aggregate (and to a tiny extent the Water) particles there are air gaps. When you mix them together, the particles fill these gaps.

And so that is why the concrete seemed to be disappearing.

So the ACTUAL volume of concrete produced was about 1/3 LESS than the CALCULATED volume of ingredients put into the mix.

So as long as this pattern is the same every time I mix the concrete (which is pretty likely as long as I use the same cement:aggregate:water ratio and the same type of aggregate). Then all I need to do is increase the volume of ingredients by 1/3.

Crisis over! Hurrah! :-)

Look Away Perfectionists...Testing the Panels

noreply@blogger.com (Gareth) — Tue, 31 Oct 2006 12:53:00 +0000

So now that I'd made a load of Textile Concrete test panels, I had to find a way of working out which ones were stronger (or more specifically, stiffer) than the rest. If I was at uni, I'd be able to take then down to the lab and use the machines to test them using lots of nice shiny equipment and computers and stuff.

But I'm not. I'm in Jozini... so I had to build a little testing rig using bits and pieces I could get from the hardware shop in town, and eventually, I managed to build... Gareth's test rig!!!

Using this rig I could apply an even load across the centre of the panel, by adding measured amounts of water to the bucket. I added 500ml (0.5kg) of water at a time and using the ruler measured how far the panel bent in the middle (or deflected to use the proper term). From this I could work out which panels were stiffer than others, and find the best combination of cement:sand:water:additive and the best curing times. Hurrah :-)

Pouring and Curing the Panels

noreply@blogger.com (Gareth) — Sat, 28 Oct 2006 16:24:00 +0000

Its amazing (for me at least!) to think that despite having spent 3 years at university studying Civil Engineering, and spending about 1/3 of that time learning about the wonders of Concrete, I’d only actually made the stuff once before. And so with a little trepidation I began casting the Textile Concrete Panels…

Just to warn you, if you’re not that interested in Concrete (ha ha, as if!) then read no further!

Concrete has 3 ingredients which you mix together: Cement, Aggregate and Water. I always used to get the words Concrete (the end product) and Cement (an ingredient) mixed up, but I digress… The Cement and Water react with each other over time and become hard. Aggregate is basically stone or sand, (both of which are a lot cheaper than Cement) and provide bulk to the Concrete. The ratio of Cement, Aggregate and Water you mix has a HUGE effect on the strength of the finished Concrete. Briefly…

Cement

The more there is, the stronger the Concrete, but remember, it’s the most expensive ingredient!

Water

It’s a bit like Goldilocks and The Three Bears. You gotta get the porridge just right!

Too much water: Makes the mix runny and easy to work with BUT as the mix dries, lots of air gaps are left AND the reaction between the Cement and Water is too quick so you get a WEAK CONCRETE. :o(

Just enough water: The mix is easy to pour AND there is enough Water for all the Cement to react fully so you get STRONG CONCRETE. :o)

Not enough water: The mix is stiff and so can be hard to work with AND there is not enough Water to react with all the Cement, so you get a WEAK CONCRETE. :o(

Aggregate

For the Textile Concrete Panels I need a runny mix that it will seep between the fibres of the textile, so I've been using use a fine Aggregate (sand). At the moment I've had to use a combination of fine sand from a nearby riverbank, and coarse sand from a big pile that happens to be lying around near to where I've been working.

I've been experimenting with different mixes to find the right Cement:Aggregate:Water mix, which takes time, but once I know these mixture ratio’s, the rest is easy! (I hope) :o)

Curing the Concrete

Once mixed and poured into a mould, you need to ‘Cure’ the Concrete. This is a way of slowing down the reaction between the Water and Cement in order to make the finished Concrete as strong as possible (anyone remember growing crystals at school, cos its got something to do with that). It was a surprise to me just how important the Curing process was, but after writing almost a page on how and why I cured the panels I realised was a bit too much to include in this blog, so if you really want to know, please leave a comment!

PHEW!

Textile Concrete Panels

noreply@blogger.com (Gareth) — Tue, 24 Oct 2006 19:16:00 +0000

For the wall panels, roof, door and pit lining I'm going to be using thin panels of Textile Concrete. I'd never come across it before but its basically plastic-fibre reinforced concrete. You make it by pouring alternating layers of a runny cement slurry and plastic textile, as you can see below:

If you want concrete panels, you used to be able to get asbestos fibre-reinforced panels, but since asbestos rips your lungs to shreds if you inhale the fibres accidentally, its been banned in most countries, including South Africa. As a replacement you can get cellulose fibre reinforced concrete panels, which I would say is a bit more eco-friendly as the cellulose is from plant pulp. Unfortunately these materials are fairly brittle, and so crack easily.

Textile Concrete, on the other hand can flex quite a lot without cracking (it is ductile rather than brittle). This (I think!) is because the cement slurry has a latex-based chemical added to it, which I guess slows down the rate at which cracks propagating through the panel.
Which makes me think, maybe if you got cellulose panels and added the additive, then you would get eco-friendly, flexible concrete panels? (maybe?) Anyway

Over the past couple of weeks I've been playing around with different types and proportions of sand (some from the hardware store, and some from a riverbank down the road) which is mixed with cement, water and a latex-based additive. I've been leaving them for a day and then putting them in a tank of water for a few days to cure, and I've been experimenting with different curing times.

Introducing... The VIP latrine!

noreply@blogger.com (Gareth) — Mon, 23 Oct 2006 20:50:00 +0000

Regular Pit Latrines, aka Long Drops are pretty much the most basic form of toilets, and are what is used by the vast majority of the world's population. (I can't prove that, but I reckon its probably true!) They are just holes in the ground with a few planks of wood or a slab of concrete over the top which you sit on when you are doing your thing. There is usually a lid over the hole, to stop flies getting in and the smell getting out.

Flies are a big problem because they mess around in the faeces, come back out of the pit and then go and sit on some food, or a person, spreading any bacteria which they might have picked up from the faeces.

In order to reduce the smell, and stop a flood of flies leaving the pit every time you take the lid off the Regular Pit Latrine, some bright spark came up with the Ventilated Improved Pit (VIP) Latrine in the 70's . The difference is the addition of a vent pipe.

Flies which are drawn by smell into the pit are attracted up the vent pipe by the brightness of daylight at the top it, but cannot escape because of the screen (unless they are clever enough to fly back down the pipe and reconsider their choice of escape holes). Wind passing over the vent pipe causes an updraught, removing any smell and helping to draw flies up to the top of the pipe. So now you don't get facaes-covered flies coming out of the toilet. Hurrah!

Here's a pic of a lady called Rosemary, sporting her brand new, and rather pretty, VIP Latrine!

For budding toilet-geeks, check out the myriad toilet options in WaterAid's technology notes.

Testing the Slab

noreply@blogger.com (Gareth) — Sun, 22 Oct 2006 21:09:00 +0000

Today I uncovered both of my dome shaped slabs. Slab#1 (which i made too thin) broke as me and Siyabonga were trying to lift it off the ground :-(
But.. Slab#2 survived!! :-)
So we tested it, first with just my weight, which was ok!:-) Then with 3 people. It managed to hold for about 2 seconds...and then broke into bits!:-(

I reckon it broke partly because we didn't have enough big stones in the concrete mix (so its easy for cracks to propogate).

The Slab

noreply@blogger.com (Gareth) — Tue, 17 Oct 2006 20:28:00 +0000

The Slab sits over the Pit. Around Jozini they tend to be made out of a 10cm thick slab of reinforced concrete with some steel rods inside them to provide additional strength. To cast them, wet concrete is poured into a wooden mould which sits over the pit, and when the concrete sets, the mould is removed.

But... I want to avoid the trouble of pouring concrete in someones back garden out in the rural areas. I want to be able to turn up at the customers with the whole loo, dig a pit, put it all in place and then go home!

So, I was looking for a way to cast the Slab in a factory, and make it light enough so that it can be stuck in the back of a buckie/ute/4x4/what Jo Mangel was always driving in Neighbours, then carried it into place over the pit.

Then I stumbled upon the SanPlat website. This had instructions for building a Dome-shaped slab which allows you to have a much thinner slab (4cm) and no steel reinforcement! And here's why...

Concrete is strong when squashed (compression) but pretty useless when stretched (tension), If the Slab was flat, then the top half of the Slab would be in compression, but the bottom half of the Slab would be in tension :-( so you would need to cast steel rods into the bottom half of the flat slab for additional strength (steel is good in both tension AND compression).

With our Dome Slab, by virtue of its shape, both the top half and the bottom half the Slab is in compression so you don't need the steel. (Trust me on this one) Hurrah for domes, and the same goes for arches too!

So, the Dome shape reduces the weight of the slab to about 200kg. Which is still pretty heavy eh? But, if one person lift 50kg then we're talking four people carrying the slab, which seems ok.

A Word From My Sponsors

noreply@blogger.com (Gareth) — Mon, 16 Oct 2006 17:24:00 +0000

For those of you wondering, "how come Gareth gets to go to South Africa and make toilets when I have to do a proper job.." I thought a few words about how I came to be out here would be handy.

I was sent here by the NGO Engineers Without Borders-UK (EWB-UK), who, in collaboration with Marie Zanders of the Engineering Firm Buro Happold, arranged for 2 volunteers to come to South Africa for 6 months to work with an NGO/development consultancy known as Esibayeni. With the assistance of the Bath branch of EWB-UK (this ones a shout out for you Mr Whitworth!) I had to raise money for my living expenses, whilst the local council here in Jozini offered to provide accomodation and a car if we helped them with some of their Engineering-type stuff.

So, these are the guys that coughed up the money to keep me fed here in Jozini!

The Happold Trust (a charitable trust closely linked to Buro Happold)
The University of Bath Department of Architecture and Civil Engineering
Richard Paice at the ISA charity
The Royal Commonwealth Society

So thank you to all of them!!!

The Pit

noreply@blogger.com (Gareth) — Tue, 10 Oct 2006 14:46:00 +0000

Ok, so lets start aat the bottom..(hahaha the first of many lame jokes) the pit is where the faeces goes, and the size of this pit can be whatever you want it to be. A sensible figure for how much faeces people produce in a year is about 65L. If we take an average 6-person family in Kwa-zulu Natal, and we want the pit to last, say 6 years, then you need a pit that is...65x6x6 = 2340L=2.34m3.

Now you don't really want to dig too dep a hole, as there is a danger that it might collapse when you are digging it, so I'll specify a depth of 1.6m. This means that the pit has dimensions of 1.2m x1.2m and 1.6m deep.

The sides of the pit can be lined with bricks to stop all the earth filling the pit in. How strong this lining is depends on the soil in which the hole is dug. For unstable, sandy soil the walls of the pit you are digging will tend to collapse easily, so you want a stronger lining whilst for more stable, rocky soil you want a weaker lining, or perhaps even no lining at all.

Irrespective of this, the bottom of the pit is unlined, as you want the liqiuds to soak away into the soil.

For the loo factory loo, we will use Textile Concrete panels for the lining. Since they do not need to be watertight, I'll try to make the panels interlocking, so that the pit lining is easy to put together. Of course it might be a good idea to offer customers the choice of not having a pit lining, if it turns out that the soil in the place where they dig the pit is sufficiently stable. In really rocky soil, on the other hand, it might be easier to to drill a narrow, deep hole using a hand-auger, if one is available.

Once upon a time in a galaxy far, far away..

noreply@blogger.com (Gareth) — Mon, 09 Oct 2006 16:31:00 +0000

Ok, so my mate Steve has got a cool blog about his 'soil-based fun' so I thought that I might give it a shot too! For those who don't know me, I'm a Civil Engineering gradute from Bath, UK and I'm volunteering with Engineers Without Borders-UK in the wonderful town of Jozini, in Kwa Zulu Natal, in South Africa.

I'm working on a loo-building project at the moment; in the area in which I live the South African government has a backlog of 85,000 outdoor toilets which it wants to build for people who currently don't have one.

The problem (as I see it) is that they can't be build the things fast enough. The government hires builders to build the loos out of concrete blocks and they are of a pretty bad standard, and take too long to put up make. The builders don't make much money out of them, which may explain why a lot of them are of a pretty shabby quality.

So... For the past 6 weeks or so I've been working on a design which uses a plastic fibre mesh-reinforced concrete panels (Textile Concrete) for the walls, roof and pit-lining and a dome-shaped slab (which I found on a website about low cost sanitation) to go over the pit.

Anyway, I just thought I'd write this as a record of how it all goes!