stitching concrete

Considreing the cement industry is the second largest CO2 emitting industry behind power generation, I am not sure whether I should be championing something else made of concrete...but....Concrete canvas is just incredible.
It's a fabric impregnated with cement which can be stretched and manipulated to make the required form. Once sprayed with water, it activates the cement which sets hard in 12 hours. The possibilites are massive, from emergency shelters and landscape control to (the probable reason it was developed) war zone environments.
Anyway, enough of the bad side, Florian Schmids' stitching concrete stools are wonderful things.
That colourful naive stitching seemingly holding the loose fabric together. It could almost be felt, something by Joseph Bueys, (I think he would have loved using this stuff). But its rock hard, how does it feel to sit on one of these? what colour does it go in rain? (it's concrete, it's fine outside), how heavy are they? Very interesting and thought provoking objects.