Signing off...

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

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

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

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!!

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!

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...

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

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!!!

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...

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.