[ayiti] Simple rubble math

Let's do some simple math related to rubble and (wo)man power.

The question is, how long would it take to process all the rubble necessary to build a single family home?

This wasn't the question I set out to answer today.  Instead, I just need to crush up some concrete debris some new friends of ours of Maple Hurst Builders gave me as part of thesis research.  The equation was actually

me + sledgehammer + large rubble + a good pair of safety glasses = crushed rubble

And certainly, the assumptions in this equation to answer the above question are that:

1. This is done by purely human power, not mechanical means (potentially applicable to areas where machinery can't be reached)
2. You have a woman doing the work (and a small one at that, given my own size)
3. The measurement is for a rubble gabion house because this building method requires hand-sized pieces.  (A rubble crusher would be necessary to make the debris size any smaller.)

Anyways, when picking up the concrete debris with my trusted strongarm Marcus, we estimated that we hauled back about half a ton of rubble.  (As in, he carried most of it.  Thanks :)  )  I broke almost all of it into hand-sized pieces or smaller in about 1.25 hours.

If concrete weighs, on average, 150 pounds per cubic foot, then I crushed about 6 cubic feet, or 0.17 cubic meters (because we like meters in Haiti - and in all other parts of the world except for the US).  A rubble gabion house contains 46.3 cubic meters of rubble (calculations based on the Haven/Oxfam gabion pilot house in Clercine).

Therefore, it would take 341 hours or 6 weeks working 9 to 5 to crush enough rubble to make the house, let alone actually build it.

This number isn't particularly significant except to say that although I'm glad I can do this work, that is a LONG time.  At least I am not making a whole house for my thesis, nor am I doing this work alone because there are such people as men and more women, and such things as machines that can help get stuff done faster.  Oh, progress.

But indeed, women aren't afraid to sweat!

On another front, my mini material tests worked and didn't fall apart!  A preview for now:

[Note: no, the one on the right is NOT a big gray cake ... although it does look like frosting.  It's hiding a secret instead!]

[ayiti] The smallest construction site

 Last night, the smallest construction site was in operation from 11:15-11:35pm. Some of my thesis studiomates had a good laugh at this process.  It just seemed so ... real yet fake.  I was working with "real" materials, yet in such miniscule quantities that it was more akin to doling out medication doses than cubic meters of construction matter.

Welcome to my studio-turn-production center.  Maybe it seems silly, but I wanted to do a (literally) little test of a recycled concrete mix design, what material is best used for formwork, and what release agent is ideal for the process.  Scaling a building panel down to 1/10th its size meant that each piece was roughly the size of a credit card.  How much will I learn from it?  Well, it's something.  The concrete is still curing.  In the meantime, I made this stilted animation courtesy of Phil's smart phone and a little bit of Photoshop* :

* while I figure out how to upload animated GIF files to this blog - 

a subject that many a blogger has struggled over but have not come up with a simple solution - 

click on the photo for now to see the animation.

It involved mixing concrete using the following essential ingredients:

• cement = Quikrete (because I don't have time for the real 7 day cure)
• large aggregate = gravel from Killian Court as "scaled rubble"
• fine aggregate = playground sand
• water = taken from the women's bathroom
• work area tarp = trash bag
• work gloves = latex-free gloves from the fab lab
• release agent = WD-40 (a real release agent, but perhaps too powerful for corrugated cardboard)

My mix design was essentially 1 part cement, 4-parts gravel (inaccurate due to using plastic cups for measurement), 6 parts sand.  I might need to use more sand and less gravel next time, or let these things cure longer since the first one broke after I separated it from the bottom formwork to reveal a mini piece of concrete reminiscent of a gray Blondie with chocolate chips.

In any rate, more experimentation to come as our thesis midreview looms!