Comments on: The comparatively short lifespan of modern concrete is overwhelmingly the result of corrosion-induced failure

By: Geopolycule

Geopolycule — Thu, 26 Jan 2023 23:48:33 +0000

No, that’s not true. Joseph Davidovits rediscovered Roman Concrete; he calls it Geopolymer, and it doesn’t have the same behavior as modern concrete because it’s made completely differently.

Type “geopolymer” on YouTube and rejoice.

By: Isegoria

Isegoria — Thu, 26 Jan 2023 17:35:06 +0000

I would think that a collapsing concrete structure would have a negative salvage value.

By: David Foster

David Foster — Thu, 26 Jan 2023 17:14:20 +0000

Both depreciation calculations and discounted-cash-flow calculations should use realistic estimates of likely building life, but rarely if ever actually do.

By: Bert

Bert — Thu, 26 Jan 2023 16:41:43 +0000

Concerning earthquakes: unreinforced Roman buildings must have been struck by quakes now and then over 20 or so centuries.

By: AJ Alpha

AJ Alpha — Thu, 26 Jan 2023 14:54:53 +0000

Concrete and steel have very similar expansion and contraction rates relative to temperature changes. Important for a reinforcement.

Not certain about basalt rebar.

Reducing the production cost of carbon fiber sufficiently might solve the problem.

I knew a concrete expert at NY|NJ Port Authority 30 years ago who had produced an example of concrete with added carbon fiber. The sample one or two millimeters thick x 2 inches x 24”. He’d sit in his office and demonstrate how he could tie it in a bow.

Carbon fiber as reinforcement could create vast new applications of concrete. It might also approach or exceed the structural capabilities of Roman concrete.