Mmm, WC fresh

Monday morning. There they are, drying away, hot n’ stinkin’. Emptied half full dehumidifier, turned 120 bricks…

Group meeting, paperwork was discussed, along with colour palettes, landscape or square, bagging up bricks for crush testing,  recycled paper, and who was doing what…

Honesty is the best policy

This definitely goes in the ‘Urine’ category.

The making of

120 crumbly lumps

Maths, window, out of… 8 rows of 15 is not 130 bricks, anyway:

Finished! Thanks to all for their surreptitious donations, we have completed the production stages of the project, and swept up most of the dust and sand…

Our blocks are now in their own hot drying room up on top of the Tower, where they will stay until they are crush tested later next week. Now, time for paperwork.

Neatly arranged. 30mm apart. Exactly 30mm.

Road trip no. 2

“The responses of the two common clay minerals in soils, namely kaolinite and montmorillonite, to varying physicochemical factors are quite drastic and opposite.”

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That article, from Canadian Geotechnical Journal, Issue 5, Vol. 35, 1999, would be darned useful, but technical gremlins have struck at the e-journal databases…and the paper copy in the library has been snaffled away by someone intent on foiling our plans! Those pesky kids…

So anyway, we need to run some tests on kaolinite clay for fairness and scientific rigour, so off to Bury go Toby & Stuart to pick up a few bags of kaolin. The air-miles on our project are quickly adding up…

More clay arrives, with more sand, though this was wet, and this blog entry would be better before the ‘It’s a no-go’ post…oh well. The super fine kaolin causes a bit of a stir, everyone has spent a few minutes handling the almost-liquid solid. And its physical properties are significantly different from montmorillonite…

The instantly recognised difference is that the optimum water content for montmorillonite is waaaay* to much for kaolin, hence the box of soup on the window ledge. So after a bit of experimenting it appears that kaolin only takes half the liquid volume to make a workable consistency ‘mud’, but still seems less stable than montmorillonite mud – the bricks are like soggy sandcastles when wet…

…but they are a lot quicker to make

Lovingly laid out

Then taken to a secret drying facility in the sky.

More stop-frame fun headed this way, keep your eyes peeled!

The mental fallout

Each of us have our own way of dealing with trauma. Tom alleviated his post-mixing-blues thusly:

Scratch n’ Sniff

Go on, I dare ya

‘It’s a no-go!’

 

Or so say some. They happen to be the ones who made the large batches of urine bricks today, so it might be worth listening to them, unless they’re sensitive Westerners accustomed to their hygiene bubble? Would anyone want to do this on a much larger scale? Perhaps we don’t realise how desperate the need for solid housing in refugee camps, perhaps people would do anything for a solid home. Perhaps they have stronger stomachs, I hope so…

Anyway…

Our 150mm cube moulds were abandoned on the premise that no bricks so far have shrunk so much they will not be suitable for the 100mm cube crush test machine… Tom donned his check shirt to construct new 110mm cube moulds with his promising protégé.

Whilst our moulds were made we assembled our equipment, including our shiny new mixer, that would solve all mixing problems with the push of a waterproof button.

First things first, have we got everything? Oh yeah, sand. Hmm, it’s really quite wet, maybe if we spread 100kg of sand out on the floor in the sunshine and wait it will dry? Erm…

Might as well enjoy it! Toby claims first sandcastle made in Arts Tower

So we need dried sand. Kiln dried sand.

Mix a bit of this with a bit of that, put in the mixer, improvise dust mask for mixer…

1 minute 59, stop! Add in the water and hey presto…or so we thought.

“Doesn’t mix very well does it?” “No, I think it’s designed for wetter mixes” “like concrete?” “yeah, I think the name gives it away”

So our saviour, the mechanical mixer, doesn’t mix dry mixes fantastically, which isn’t fantastic. Back to hands-on, which is OK with water, but the smiles rapidly disappear…

“…so I said”

 

A perfect cube…then the smiles fade

“This is a high stress situation”

“Don’t touch my sleeve!”

Aren’t they something? Wasn’t it worth it? Wasn’t it?

What soil? What consistency?

To find out, we ran a few tests, see video below…

We were aiming to decide upon a suitable clay content and a suitable liquid content for the main experiment, in order to remove as many variables as possible.  Batches of dry ’soil’ were made up with 5%, 10%, 15%, 20%, 25% and 30% clay mixed with dry sand.

An equal (300ml volume) sample of each batch was mixed then with between 25ml, 50ml, 75ml, 100ml, 150ml or 175ml water, and sent for various tests…

The much mentioned drop test was carried out as per detailed instructions, a 40mm diameter ball of each mix was dropped 1.5m onto a board, inspected, photographed and added to our drop test matrix (video below)…notice the diameter gauge on the table.

Cohesion and consistency tests were carried out by a dedicated team of specialists, whereby a 30mm diameter ball is rolled between palms into a thin sausage to determine whether or not it holds together in small quantities.  Another sample of soil if made into a ribbon and slowly lowered over the edge of the palm to test the plasticity and cohesion.  The jury is out on the accuracy of the latter ‘field’ tests, with varying degrees of error documented, though we found it a useful exercise, the results correlated more or less with the drop tests.

The proceedings were meticulously documented, sparing no thought for Health and Safety

After all that we discussed our findings and decided on the clay content, and an ‘optimum’ liquid content for the following days brick making.

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