That's one possibility, but it depends a lot on where the money gets injected and where the inflation happens. If it balloons real estate prices before wages catch up, you don't necessarily get that growth of investment into productive areas. Instead it gets more expensive and riskier to start a business, with higher rent payments, and meanwhile a lot of asset-owners retire on their newfound wealth. It gets harder to convince lenders and investers to put money into real production when speculating on land and collecting rents starts getting such good consistent returns.
Interest rates will fall but beyond that it's very non-obvious what will happen. Money becomes a hot potato? Cashflow-generating assets get bid up to extreme valuations? Speculative assets like crypto gets carried along for the ride? An increase in private borrowing, the money supply, the velocity of money, and inflation?
On the other hand, the government debt interest burden goes down, which means a slowdown in the growth of the base money supply (even while borrowed money increases). Perhaps this slows long-term inflation, but that in turn might mean inflation driven by growing private debt and speculative malinvestment swings well past equilibrium and turns into a bubble that pops into eventual deflation.
Interesting. It's not just the absence of rebar, and it's not survivorship bias. It's a hot-mixing method that results in both rapid curing times, and self-healing of cracks. A lost technology, rediscovered.
Is it reasonable to build concrete structures today without using rebar? And is it true that rebar actually makes concrete structures less durable over longer time scales?
I've long been attracted to the idea of building a building with Roman concrete and no rebar that would last centuries... Guess it's a sort of vanity project. :)
You can't build sky-scrapers without rebar (i.e. with un-reinforced concrete), but you can build some pretty large structures if you use curves, arches, widening bases, buttresses, etc. The Pantheon is pretty big, built from un-reinforced concrete, and nearly 2000 years old.
You have to adapt your building style to the material you're working with and tall, thin structures depend on the tensile strength of steel; concrete doesn't have much tensile strength, but does have tremendous compressive strength, so your structure will have to be wider at the bottom, although not necessarily wider than it's tall. It's all about directing the vectors of forces in a way that they stay inside the material of the structure, so no flying slabs, upper floors have to have arches or domes supporting them from below (or lots of pillars that widen into a small arch at the ends).
Here is an idea for a technique may be useful for building with un-reinforced concrete: instead of pouring whole walls into a mold, pour "lego"-style interlocking (large) blocks, layer by layer. Between layers you paint the surface with a thin layer of weak but flexible mortar or glue before pouring the next layer. This way you keep enough room for the structure to shift and settle without cracking and you can use the angle of contact between blocks to deflect the vectors of force back into the material. The article mentions that the Roman-style concrete hardens much faster, so that'll work well with this idea (you don't have to wait too long between pours).
As for rebar making concrete structures less durable; yes, that's certainly true for steel rebar. The reason being that it will rust, very slowly at first, but once it starts the expansion of the rusted part causes cracks in the concrete which allow more humidity and oxygen to reach the steel, thus rusting faster. This is often called "concrete cancer", and limits the useful lifetime of most modern reinforced concrete structures to between 50 and 250 years (depending on the environment they are in, the forces they are exposed to, and the quality of the concrete they were constructed with).
Concrete cancer can be reduced or even eliminated by using rebar material that rusts more slowly (stainless steel) or not at all (carbon fiber), but these are much more expensive of course. There is room for research on other reinforcing materials, but basically nothing with good tensile strength is going to be cheaper than steel and considering the quantities of rebar we use, cost is definitely a major issue.
The self-healing nature of Roman concrete might also help here, but the chemistry of concrete and rust formation on embedded steel is complex, and without extensive experimentation right now we don't know if steel embedded in Roman concrete rusts faster or more slowly than in modern concrete (before considering cracks).
I think the problem is the kinds of structures we want to build. The Romans built everything supported by arches, where the loads are all distributed in compression. But to make a glass-walled multistory apartment building with overhanging balconies you definitely need rebar to handle those tensile loads.
Modern concrete is also self-healing to a degree, while being vastly stronger. It's just subjected to incomparably higher stress. We also never really "lost" the method of making concrete self-healing, t's just never been a priority.
The self-healing capacity of ordinary Portland cement is very limited, but it's there, and you can easily find literature backing this fact up, e.g.[1]
You can also trivially look up strength figures of OPC concrete vs Roman concrete. Modern concrete is overwhelmingly stronger, and can be made even stronger where it needs to be.
As for being subjected to incomparably higher stress... are you really claiming that Roman architecture was ever subject to anything comparable to thousands of multi-ton vehicles driving at dozens of kilometers per hour? Or to anything comparable to the weight of a high-rise building?
And don't forget that it made heavy use of arches, which isn't necessary anymore thanks precisely to the strength of modern concrete.
We also know what the composition of Roman concrete was, and there's literally thousands of publications on self-healing variants of concrete. You can buy most of them. They're just not a priority for most applications.
People really need to stop romanticising Roman concrete. It was incredible, sure. But it's got nothing on modern cementituous material science.
It's a subtle but very impactful difference. Japanese faregates also typically have two sets of doors, allowing them to close in front of you whichever direction you are moving. So people can go through at a fast pace and very tightly spaced, and the door still closes in front of the correct person.
They also have the display screens located farther ahead so you don't have to stop walking to see how much fare you were charged.
Wasn't the Moskva caught sitting there with its defence radars switched off? I think that was a big fumble by the Russian navy but not necessarily reflective of any fundamental shift in the broader landscape of ships vs missiles.
In my (admittedly not ship-building) experience, big problems happen when design and manufacturing are done by different organizations. The designer has to make guesses about the tools and processes at the manufacturer, and the manufacturer has little flexibility to make small changes to the design to improve manufacturability.
Of course there are ways to bridge this gap, including close collaboration and frequent back-and-forth between groups, but then when the spec has been fine-tuned for one manufacturer it can end up nearly impossible for third parties to competitively bid for a contract.
I think the navy can probably do design as well as anybody, but then they'd probably have to run the shipyards too.
The alt case isn't the shipyard doing the design; it is gov't working with consultants on specs, working with designers who work with engineers who work with manufacturers who work with subcontractors
Indeed, usually if I'm using C these days it's because I only have access to a c compiler for my target platform, or because I'm modifying an existing C codebase.
Kind of like how an O(n^2) sorting algorithm sorts n^2 elements in time n. Right?
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