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Comment by pjc50 | Hacker News Reader

I wonder what the practical limit is on how thin and light you can make concrete for non-structural items? I can see someone selling concrete mugs on Etsy, for example. Maybe with clever use of fillers and thin walls you could have a version of this you could actually lift. It looks great, especially in contrast to a white IKEA-style office.

Re: decay, I regret not taking more photos of the final days of the RBS "Ziggurat": https://www.edinburghlive.co.uk/news/edinburgh-news/stark-ph... ; at the end it had plants growing from much of the upper levels, making it look extremely Horizon Zero Dawn.

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People who make concrete counter tops use a lot of fibreglass fillers to get them fairly thin but if you wanted it truly light weight you’d probably need to make it out of a dense foam and coat it with something that looks like concrete.

Concrete counter top mixes usually use either much smaller, or no aggregate and use more sand. The mixes resemble mortar more than concrete and they are typically a little harder and less forgiving to work with.

My bathroom is a couple mm of microcement over Schluter Kerdi-Board foam, it's fairly strong. I think it can hold a laptop no problem.

There are a range of rendering mixes that look pretty much like concrete, or at least mortar, that would do the job. In fact just rendering it entirely (base coat, plastic reinforcing mesh, top coat(s)) should give a concrete-ish look while keeping things fairly light.

> if you wanted it truly light weight

Aircrete with a good sealant because obviously it would be even more porous than regular concrete https://www.youtube.com/watch?v=z4_GxPHwqkA

Even structural items can be made quite thin! There is a college design competition to make concrete canoes which can be 3/8" to 7/16" thick: https://www.concretecanoe.org/2008Triva/Florida2008DesignPap...

oh wow that takes me back. I remember touring, i think it was Texas A&M, in HS and they showed off their "concrete canoe" to the group. This would have been in the late 1900s.. 1995 or around there.

There have been ships made of concrete.

https://en.wikipedia.org/wiki/Concrete_ship

I've read that adding a little bit of graphene can make concrete much stronger, lighter and easy to shape, so would allow for thinner objects.

There are a lot of additives to concrete - the industry is large and has put a lot of money into research over the decades. You can read many many books on the pros and cons of different options.

Translucent concrete: https://www.allplan.com/blog/translucent-concrete/

You could mix concrete with other materiais too. I worked as a lab assistant in a engineering lab for some time. Putting styrofoam into the mix would result in lighter concrete within acceptable levels of resistance (for low level buildings). You might be onto something

> Maybe with clever use of fillers and thin walls you could have a version of this you could actually lift

You could likely also pour something like this out of aircrete, which would make it a lot lighter even at the same thickness

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