Self-healing of lime based mortars:
microscopy observations on case studies https://repository.tudelft.nl/islandora/object/uuid:ff226ad0...
Although it is true that sand from different geologic deposits can show vastly different results when used in the same building product. Superior binder plus superior aggregate could make superior concrete.
> sand from different geologic deposits can show vastly different results
That's the other bugaboo about portland cement, Aggregate expansion/alkali-silica reaction/concrete cancer. They used the wrong type of aggregate and dune sand in the old foundation of my house (rental not my problem unless I'm in it during the next earthquake). So now it's crumbling.
Granted if you keep reinforced portland cement dry, it's fine. Otherwise eventually it'll fail.
And I don't see why we couldn't add fungi to this mix. Along with Titanium Dioxide:
https://www.sciencedirect.com/science/article/pii/S095006181... [check the citing papers: https://scholar.google.com/scholar?cites=1362107164675591553...]
And also, we have polymer based cement nowadays:
The "Journal of Materials in Civil Engineering" back in 2013 had a special issue on "Materials Innovations for Sustainable Infrastructure":
And here's a 2017 "Review on Characterization and Mechanical Performance of Self-cleaning Concrete":
In addition to this, here's a 2008 article from MIT Technology Review on concrete specifically designed to capture somewhat absurd amounts of CO2:
And then there's this whole glow in the dark concrete business:
The highly inovative thing about this glow in the dark cement isn't that it glows in the dark - it's the fact that it's UV condusive, similar to translucent concrete:
And this distinguishes it from the much older glow stone concrete tech, marketed by companies like Ambient Glow Tech:
And many other companies. Although that kind of stuff also seems really really nice.
There's also LiTraCon, which adds optical fibers to the mix:
Like many fields of science, material science seems to have become absolutely crazy in the last two decades with a huge swath of research, so much of it that nobody actually manages/bothers to combine all the disparat and different discoveries into one huge gigantic leap. Instead you get special materials A to Z, each with their own special flavor. It seems highly likely that ~7±2 years from now, someone will come along and do so, synthesizing the majority of these discoveries into one bigass leap in material science. If it hasn't happened already in someone's head and we'll find their paper on arxiv later this year. I'd speculate this will likely come out of either India or China, as western patent laws would make any such leaps-and-bounds innovations absurdly expensive with gigantic patent wars happening. Whereas if China or India suddendly start using concrete of this kind inside their own countries only, what you gonna do about it to stop them? Sue them? Watch either of them give negative shits. (I could see this becoming problematic with China and their massive road construction in Africa tho.)
To provide some additional future speculation:
It seems likely to me that this will then lead a pseudo-revival of Brutalist architecture, but modified by knowledge we have today, with structures appearing, paradoxically, as both more organically rounded (hence the pseudo-, since that won't match the Brutalist style) AND more synthetically jagged.
I say this because:
1. It seems almost certain to me that any such 'new concrete' would end up a lot less grey than Portland cement, if you look at Roman concrete as an example, both normal Roman concrete and Roman marine concrete have a color significantly less grey than normal Portland concrete. Adding Titanium dioxide and other materials innovations to that would likely shift this further into a more white-ish hue.
2. It seems highly likely to me that they'll modify the Trichoderma reesei from the parent article to include bioluminescence. Likely for the purpose of making it easily tracable in the concrete as part of research. And then someone in the lab will go "wow that looks pretty". Combine this with what I've already pointed out and you'll get very crazy looking buildings.
3. We know a lot more about the geometry of architecture than we did in the last century. For examples, see here:
* Everything ever done by Christopher Alexander (https://en.wikipedia.org/wiki/Christopher_Alexander)
And many more reason I don't have the capacity to go into right now, consider this only the tip of a very large iceberg.
The point is that the vast majority of modern concrete, especially using rebar, will last decades compared to some Roman concrete, which has lasted millenia.
>The seawater instantly triggered an exothermic chemical reaction. The lime was hydrated – incorporating water molecules into its structure – and reacted with the ash to cement the whole mixture together.
CACO3 -> CAO + CO2
Plus the CO2 released by fuel used in the burning process.
A developer recently built a 20 story apartment building next to my office window using entirely a reinforced concrete frame. I was incensed to find out that because of "concrete cancer" , the lifespan of that building may be less than 70 years. But the more I thought about it, the more I began to believe that maybe the additional lifespan is not an asset. The building is attractive today, but might not (probably won't) appeal to people 40 years from now. Furthermore, buyers are going to want different things from their homes (look at the popularity of open kitchens 40 years ago vs now). And I began to realize that it would be
quite difficult to design and build a building that would be useful beyond 70 years from now.
Another way to look at it is that the marginal value of 10 years of longevity is not that large out 80-90 years. I think you'd have a difficult time finding a developer who would pay 10% extra to get a building that lasts 100 years instead of 90.
This line of reasoning leads to an icky "planned obsolescence" approach, but I think these are the economic realities.
LEED certification includes a credit called "good bones" which recognizes that although exterior trends change, the concrete bulk of a building can be reused if kept in good condition. A new facade can completely rejuvinate an otherwise dated structure. Most concrete building construction focuses on creating large open floors with columns to provide the largest flexibility in floor plan.
An additional interesting trend I've been seeing in Chinese construction is the construction of structures with double the standard height between floors. These buildings can be finished with units with features such as high ceilings and loft spaces that most high-rise units cannot accommodate.
If it was just the rebar, we could replace the iron rebar with drawn basalt fiber rebar.
Perhaps in the future, structural concrete will be covered in an outer layer of ceramic that is subsequently vitrified at a certain stage in curing. You keep your building from collapsing by burning it in a towering inferno first.
Another thing you can do relatively cheaply (I think) is powered cathodic protection. I don't know if they bothered to do that on this building.
It was a while back but I recall that the characteristic map cracking and eventual failure need salty water as well as the correct chemical composition of the cement used. I think there are something like three conditions needed. Stop one and you fix the problem. I seem to also recall that PP's Civ Eng dept did a lot of work on this in the '80s. Plymouth is a sea side city and has a lot of concrete structures that suffered eg Charles Cross multistory car park.
To be honest I would find it hard to believe that a structure that size would be designed to that short time scale. I'm not familiar with Aussie building regs (I'm not familiar with anyone's outside the UK and saw a.com.au link!) but it would be very hard to design for so short a lifespan. There will be a minimum conc. depth to the reinforcing bars, just for fire regs, let alone spalling. If the weather is a bit fierce then the other design criteria like being able to withstand a 1 in 100 or 200 or whatever year event will also play a part in the lifespan. Obviously there will also be a factor of safety applied which could be as high as 1.4. Take a close look at the final finish, it may have been sealed in some way. Keep the water and freeze/thaw and the like away and conc. can last a bloody long time.
You're right in that certain buyers are going to be looking for certain elements that might not make much sense from a long-standing building point of view. Architectural shapes and trends change over time.
On the other hand, its also true that a lot of these trends are just bad architectural design. Period.
Sunken lounges of the 70's. Media-rooms and conspicuous consumpition-esque cavernous entrances and questionable elements in macmansions. These are designs that are incredibly difficult to repurpose into anything but their original purpose.
In my country (Aus), there is a now a common suburban design that almost entirely ignores long term elements and lessons of the environment that have been known for at least 100 years: see https://en.wikipedia.org/wiki/Queenslander_(architecture). Now we have a poor relation of the generic american style: dark roofs and colours, no overhangs/shelter/verandahs, directly western facing living areas and frontages, all designed to maximize internal sq meters/price.
Now, i appreciate that my queenslander example is a style built of wood traditionally. But there is another style example of highly valued real-estate with long term potential in the urban centres: victorian terraces and townhouses. Aside from the regrettable wealth signaling effect of owning one, its an architectural form that has lasted the test of time and is arguably constructible via concrete. And one of the reasons it has done so is because that form is the complete opposite of the media room/sunken lounge/mcmansion: almost universally flexible and readjustable. A proper Victorian townhouse in its context can be reclaimed and used as a bar, as a restaurant, as a residence, as an office or a place of business. Though like all succesful architecture, this is only because it works in the context of its environment.
Brass is unlikely, copper is the material. The oldest pipe work I found was steel in our place - it was hard and weighed a fair bit. Copper is maleable, easy to bend and braze joints on to. It does corrode eventually but I think the thin layer of copper oxide that forms then seals in the pure copper, protecting it. The longevity of copper can be seen in the green roofs of some churches which must have looked absolutely stunning before oxidizing.
Similar process with bacteria rather than fungus from 3 years ago
Pure calcium carbonate is not as strong as concrete. It sounds like this will just fill in cracks with weaker material, hiding them from inspection, which would be even worse --- the strength of the material is degrading but not visibly.