Spheres can make concrete leaner, greener | Hacker News Reader

Spheres can make concrete leaner, greener

phys.org

43 pointsdnetesn28 comments

I would feel a lot more comfortable with these spheres being used in construction if they were 1000 larger in diameter. The size cited is 50nm to 100nm, roughly the same size as another non-reactive compound that is believed to have real risks associated with it, titanium-dioxide. See https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3873219/

I hope they dont cause any weird diseases.. I'm just thinking of asbestos-concrete.. It was amazing at the time, far greater tensile strength and fire safety.

And also completely not dangerous, yet it received the banhammer

I wonder what the impact of the collapse of the twin towers would have been if the concrete used had contained a significant fraction of aesbestos?

In what manner is the risk eliminated?

Because of the cement the asbestos is not friable and thus doesn't pose a mesothelioma risk. Sure, it'd not be great to do lines of ground up asbestos fiber cement, but that has a lot more to do with it not being a good idea to do lines of cement in general and nothing about the asbestos side.

cement degrades, though, and drilling into cement is a common thing. afaik any asbestos in products is toxic if it can enter the air. What about the cement mix before water itself?

This comment is so naive and ignorant, it hurts. I'm sorry to be so harsh, really, but I hear this bullshit depressingly often, and ignorance like this has really contributed to an epidemic of asbestos contamination that is still very much with us.

Cement is a temporary matrix. Concrete and other cementitious structures are constantly weathering, degrading, and being demolished all around us. Right in my own back yard a 30-year old concrete patio is spalling, the flakes slowly turning to fine dust with every foot fall. Dust which is then blown about my yard and tracked into my house. Do you imagine that dust would remain "completely not dangerous" if it contained asbestos?

And apparently you've never worked with concrete or grout, because otherwise you'd have witnessed the unavoidable clouds of cement dust that erupt any time you open a bag, pour, shovel, or even breathe on dry mix.

> it'd not be great to do lines of ground up asbestos fiber cement, but that has a lot more to do with it not being a good idea to do lines of cement in general and nothing about the asbestos side.

Any asbestos in ground-up fiber-bearing cement would be, by definition, friable. That's what the word means.

Long time ago I'd hear people say the same thing about asbestos cement siding -- as though the cement will encase the asbestos for all eternity. As though no one ever re-sides their house, or as if re-siding never involves breaking or disturbing the old siding. The abject stupidity of such assumptions is immediately apparent the moment you break a piece of siding, either during installaion or removal, and you see a puff of asbestos and cement dust spring into the air.

Again, I'm sorry for speaking harshly, but asbestos kills, and people like you who spread the "asbestos is safe when properly applied" bullshit have made it that much harder for us to get rid of the stuff.

Ate you saying asbestos bound in cement is not dangerous? That's simply not true. Things like wind erosion, wear and tear, accidental breakage, can cause the fibres to escape the cement. This seemingly simple problem makes it very difficult to safely demolish buildings that were built in the golden age of asbestos.

Asbestos battles are still being fought in Belgian courts, because workers who produced/installed/removed it got sick.

It's already used in food: https://en.wikipedia.org/wiki/Calcium_silicate#Use

even though you can eat it without risk, nanoparticles can be aerosolized, and cause injury to the lung that is unique to that route of administration.

think of how different it is if you ingest vs. topically apply alcohol. This is the same issue: you can't necessarily extrapolate toxicity with one route to toxicity with another.

Aircrete is similar and very interesting: mix fine dishsoap bubbles into concrete and you can actually reduce density so much that it will float on water!

Concrete boats.

The US military actually used concrete 'blockships' to create an artificial harbor for use in D-day. Doesn't need to be aircrete to float if correct shape!

https://warfarehistorynetwork.com/daily/d-days-concrete-flee...

>micron-sized calcium silicate spheres

Wonder what these will do when the concrete eventually degrades. How do these spheres act in the environment? what happens when they end up in the water system and are ingested by animals (including humans)?

"Calcium silicate is used as an anticaking agent in food preparation, including table salt and as an antacid. It is approved by the United Nations' FAO and WHO bodies as a safe food additive in a large variety of products." [1]

This does not invalidate your questions, however. No idea what happens when "anticaking agent" ends up in everything.

1 - https://en.wikipedia.org/wiki/Calcium_silicate#Use

Micron sized should be fine, and they’re going to form a. God phase when hydrated so you don’t have to worry about long-term friability. Nanoscale would be a concern because of the ability to directly enter cells, but micron would be fine unless you’re breathing a cloud of the stuff when it’s fresh ad dry. Under normal wear and tear that won’t happen.

"a. God"?

My fat fingers and iPad’s autocorrect is a bad combo. Should read: Gel phase.

God phase would be... nifty?

After a bit of research it looks like it would be replacing Portland cement which is made with limestone, clay, and gypsum. Which makes me wonder how cost competitive this will be, since those materials are very cheap.

You forgot about energy in your list of ingredients. Portland cement needs a lot of energy to make. The materials you list are the cheap ones, energy is the expensive one.

Perhaps this could end beach and river bed theft?

Can you elaborate? Is concrete regularly stolen from beaches?

Sand is stolen in large quantities in many countries to be used in concrete production.

Example: https://en.m.wikipedia.org/wiki/Sand_mining_in_Tamil_Nadu

Since these are round and they're going for jagged sand, probably not?

How quickly can this be replicated? Huge business potential.

Based on my previous experiences with disillusionment, here's my rule of thumb:

Late stage research announcement to viable product/start-up announcement: 1-2 years

Start-up to commercially useful: 2-3 years

Commercial viability to industry impact: 3-5 years

Can go quicker and if research is preliminary can go much longer. But this is what I tell myself when I see something I'm excited about

Good reminder! Also to mention: When researchers research about some new Magical thing, they need to also come up with potential applications to continue receiving funding, prospective interests, get publicity, etc.

It is very possible that this article could be nothing more than: Researchers unveil new nano-material with high strength properties, cite concrete as a possible application supplement.

Reply on news.ycombinator.com