
Riddle of cement’s structure is finally solved - augb
http://news.mit.edu/2016/cement-structure-solved-0208
======
devindotcom
I love these base-level, practical advances where even a slight improvement in
a formula (provided it is not closely guarded) can, say, improve the strength
of a material by 5-10%, meaning that much less of it must be used, which at a
scale like concrete's can make for huge changes in usage, markets, processes
etc.

~~~
samcheng
Concrete is a HUGE greenhouse gas source, so this is also a great boon for the
environment. It's estimated that concrete is responsible for 5% of all
anthropogenic CO2.

[https://en.wikipedia.org/wiki/Environmental_impact_of_concre...](https://en.wikipedia.org/wiki/Environmental_impact_of_concrete#Carbon_dioxide_emissions_and_climate_change)

~~~
justinpombrio
I hate to break it, but it could actually have the opposite effect by
disproportionately increasing our consumption of concrete.

[https://en.wikipedia.org/wiki/Jevons_paradox](https://en.wikipedia.org/wiki/Jevons_paradox)

~~~
eru
At least we get more concrete out of it..

------
givan
There are more riddles to be discovered

[https://en.wikipedia.org/wiki/Egyptian_pyramid_construction_...](https://en.wikipedia.org/wiki/Egyptian_pyramid_construction_techniques#Limestone_concrete_hypothesis)

Utilizing scanning electron microscopy, they discovered mineral compounds and
air bubbles in samples of the limestone pyramid blocks that do not occur in
natural limestone.

------
kagamine
This may be a stupid question, but given the apparent interest and knowledge
of concrete in the comments here, it seems like an appropriate time and place
to ask:

Why can't they make coloured concrete?

Painting it doesn't seem to last/work. It is grey, always grey. Is there no
way to apply colour to the mixture and retain its strength?

~~~
mitchtbaum
> It is grey, always grey.

Check out Decorative Concrete:

[https://en.wikipedia.org/wiki/Decorative_concrete](https://en.wikipedia.org/wiki/Decorative_concrete)

[https://www.pinterest.com/explore/decorative-
concrete/](https://www.pinterest.com/explore/decorative-concrete/)

Bonus 1) Translucent Concrete:

[https://en.wikipedia.org/wiki/Translucent_concrete](https://en.wikipedia.org/wiki/Translucent_concrete)

[http://google.com/search?tbm=isch&gws_rd=cr&q=translucent+co...](http://google.com/search?tbm=isch&gws_rd=cr&q=translucent+concrete)

Bonus 2) White Concrete, using Titanium Dioxide admixture, also cleans itself
and its environment:

[http://google.com/search?tbm=isch&gws_rd=cr&q=concrete+tio2](http://google.com/search?tbm=isch&gws_rd=cr&q=concrete+tio2)

Bonus 3) Nanomaterials add a lot of new potential for strength, possibly
color, as well as completely new applications. For instance, carbon nanotubes
make concrete slightly electrically conductive, which makes it possible to do
easy integrity testing, visible from low voltage current fluctuations near
stresses, strains, cracks, etc. I wish I had more info on a prospective range
of applications here.

Aside A) Clays (of possibly many colors) can also provide an even cheaper,
more readily available, and similarly strong building material. Sindhi
researchers pre-stressed and baked some test beams, and they were just about
as strong as comparable concrete. See Emergence of New Era for Reinforced
Baked Clay Construction (Memon, Bhatti, & Ansari):
[http://www.quest.edu.pk/rjournals/julydec2013/julydec2013_1....](http://www.quest.edu.pk/rjournals/julydec2013/julydec2013_1.pdf)
I sincerely wonder how this ongoing wealth of research on concrete plus many
generations old, likely undocumented, skill we have with clay construction
could come together.

------
ihartley
Here's the PNAS article that they don't link to in the article for some
reason:
[http://www.pnas.org/content/early/2016/02/04/1520487113.abst...](http://www.pnas.org/content/early/2016/02/04/1520487113.abstract)

~~~
jcr
Thanks for the link, but it is in the article. On news.mit.edu articles, when
they do include links to papers, the links are presented in the "RELATED" list
on the right side. They don't always remember to give links to papers, but
they are better about it than the press/news sites of most universities.

------
sharp11
This is great! Basically cement is a fractal substance. Are there other known
fractal substances?

~~~
dalke
[http://www.ncbi.nlm.nih.gov/pubmed/2577851](http://www.ncbi.nlm.nih.gov/pubmed/2577851)
from 1988 starts:

> In recent years it has been shown that the structures of a wide variety of
> colloidal aggregates can be described in terms of the concepts of fractal
> geometry. The purpose of this review is to discuss some of the evidence for
> fractal geometry in experimental systems and indicate how fractal geometry
> can be used to develop a better understanding of their aggregation kinetics
> and physical properties.

so I think the answer is "many". Try
[https://scholar.google.com/scholar?q=fractal+material](https://scholar.google.com/scholar?q=fractal+material)
for some pointers.

~~~
sharp11
Thank you so much for the pointers. So fascinating!

~~~
dalke
Google Scholar is a great resource for these sorts of research-oriented
questions. I hope you continue to find it useful.

------
mbroshi
In case you are not already excited by discoveries in concrete, this should
help:
[https://gimletmedia.com/episode/3-concrete/](https://gimletmedia.com/episode/3-concrete/)

