Engineering360: "Watch how cement-free concrete bends"

So the polymer slab bends but it remains deformed after the pressure is relieved. Can this be a good thing to have a polymer acting like a metal? What effect would the deformation have on a wall or bridge, not a good result I think.

<...deformation...polymer slab...on a wall or bridge...>

One wouldn't design such a structure using this material in the domain where it would do this, in the same way as one wouldn't craft the proverbial tea pot out of chocolate.

is it

Very cool - it should have a large number of very useful applications with this ability to withstand catastrophic failure.

When sustainability is being assessed, it is great that it uses a previous waste material and requires considerably less additional carbon emission than manufacturing virgin concrete; however, I wonder about the ability to recover/reuse/recycle this material at end of life.

Often, we engineers fail to design for complete life cycle environmental impact because generally end of life costs are not born by original manufacturers.

Business interests don't impose this constraint on design and too often are in opposition, particularly in the absence of strong social policy constraint.

Would a bowed bridge deck not fall from it's piers?

Perhaps the applications for this are specific, such as building slabs or in the case of a bridge; would be more akin to a suspension or truss design.

It is very interesting to find the trifecta.... cheaper, stronger and greener.

But for longer spans, how could this work ?

Seems like it would work fine considering that a structure made of cement would be fractured (instead of bent). That's generally a more deisreable failure mode.

Concrete:

Tensile strength - σ : 2 - 5 MPa (300 - 700 psi)

https://www.engineeringtoolbox.com/concrete-properties-d_1223.html

Strain-hardening geopolymer composite (SHGC):

Tens. Str.: 4 MPa

https://www.sciencedirect.com/science/article/abs/pii/S0950061816318876?via%3Dihub

**Bending being more desireable than fracture.

At any point where the SHGC would bend, concrete would be fractured...