Comment by jauntywundrkind | Hacker News Reader

Comment by jauntywundrkind | Hacker News Reader

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jauntywundrkind

I cannot say enough how much as I've aged I've come to appreciate how lots of big dumb matters around me feels essential to have peace & quiet.

You can find a peaceful out of the way place where there isn't sound or people, or you want stone and concrete aplenty around you. That's weight & mass. But that mass usually has so much cost. (And it has so many inconveinences. Where do the pipes and wires go when you are working with stone? It's not accommodating like framing & drywall.)

This is so cool. This is so so so cool. It's cheating, getting one of the best & nicest things you can get, and doing it not by just cladding your world in thick concrete, but by creative use of negative spaces. By resonance. It's a vast unmaterial triumph. Using much less matter but getting so many of the same upsides.

This is the arch of victory that embodies what I hope can carry us through the stars for a long time: getting so much from so little. Making stuff that is blisteringly effective. These are the triumphs that can sustain us as we voyage on.

(It also looks like something that would be pretty easy to mass produce! A bit bulky to transport though, but maybe there are some creative solutions.)

listen, if you want a bunch of concrete cheap, i gotta tell you people will literally pay you to haul away their construction waste, which is mostly concrete. it's almost 2 tonnes per person per year: https://www.epa.gov/smm/sustainable-management-construction-...

what's expensive isn't the stone and concrete. those are cheap as shit. even graded broken stone aggregate for mixing concrete is cheap. like a penny a kilogram cheap. sand, same story. random dirt is even cheaper and works fine to block sound

what's expensive is shaping the concrete and dirt (for example, as you point out, to run pipes and wires through them, but also for things like making thin walls stand up stably)

to a lesser extent, getting it delivered is also expensive, because it's heavy, but mostly it's the shaping. that's why concrete is so popular; concrete is mud, and mud is pretty easy to shape, but it's mud that turns into stone overnight. it turns out that it takes a lot of work to shape big things

The low-tech "old farmer" Goldilocks solution I've seen is to mostly fill in the large gaps with free concrete rubble or stones, so a lot less (expensive) concrete is needed to infill the rest.

But that ain't sexy, so most people ignore it. :)

Obviously it's somewhat impractical on large jobs, and inadvisable in very strength-critical roles, but for small household / farmstead projects it's a great way to save money and get rid of ugly rubble you have lying around.

Yep. Don't use expensive, new, pristine, energy-intensive materials wherever possible. Reserve those for finishes and exterior coatings. Appropriate filler materials should be suitable for the strength, longevity, and safety profile and function desired.

This also reminds me of some DIY and volunteer experiences installing residential fence posts. On a volunteer gig, I saw people using 200 lbs. of concrete and keep adding water until it's soup triumphally proclaim it's "the right way" while dismissing supervisors and others who knew what they're doing. Meanwhile, I was looking at depth, slope, wind risk, and soil (hydrology), and gathering site debris like rocks and chunks of metal to stick under each post so it wouldn't rot in 5 years or become the Big Dig in time, materials, or quality.

Thanks, you said it better than I could. Nicely encapsulated the whole picture.

yeah, despite my extremely limited construction experience, i've done this, recycling concrete as aggregate

also though 'fill in the large gaps with aggregate' is what makes concrete concrete instead of cement

however, if you want to make soaring thin shapes out of concrete, you aren't going to do that with chunks of demolition debris as aggregate. even gravel won't do. for ferrocement you need an all-sand aggregate, and mining construction sand is a lot cheaper than crushing demolition debris into sand

Used bricks is very sexy solution. However it’s getting harder and harder to find old buildings to be demolished. And I wouldn’t use these bricks for critical infrastructure.

Yeah for something you're gonna see, bricks are fantastic. If you're just making an anchor for a post or similar, rubble-infill concrete is a great cost saver.

Figuring out the volume of your rubble so you can mix/order the right amount of concrete can be a bit tricky.

> getting so much from so little

I feel the same way about directly using or mimicking systems of the natural world. Stuff like using birds as combined pest control and fertilizer or waste water treatment.

I think we haven't even scratched the surface of what is possible, particularly with microbes. I envision things like producing glue, converting plant scraps into fibres/wood, converting toxins into inert compounds, extracting trace chemicals from a massive volume of useless medium.

Right now I think the biggest obstacle to these kinds of techniques is the lack of control and the danger of escape and mutation. Just imagine if a plastic-eating bacterium escaped a waste facility and started eating our world. I hope that with better tools and better simulation we can make it work and make it safe. It would go a long way towards lowering our energy and resource use.

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