So RE my critique of the 3D printed houses using a lot of concrete and, therefore, being carbon intensive:
QuoteMontreal company Carbicrete has developed a method for sequestering carbon in concrete, claiming its product captures more carbon than it emits.
https://www.dezeen.com/2021/06/15/carbon-capturing-concrete-carbicrete
Another:
"uses an enzyme that automatically reacts with atmospheric carbon dioxide (CO2) to create calcium carbonate crystals, which mimic concrete in structure, strength, and other properties, and can fill cracks before they cause structural problem"
Self-healing concrete could multiply lifespans of structures
https://phys.org/news/2021-06-self-healing-concrete-lifespans.html
>>fill cracks
I wonder if it's related to research a few years ago that figured out how the Romans made better concrete that we can (or could prior to 2017 anyway).
Time, 2017:
QuoteModern cement mixtures tend to erode, particularly in the presence of seawater, but the Roman recipe of volcanic ash, lime, seawater and a mineral called aluminium tobermorite actually reinforces the concrete and prevents cracks from expanding, researchers found... While the Romans benefited from more access to natural volcanic ash, the concept could one day be used as a more environmentally-friendly alternative to modern cement mixing, which emits a significant amount of carbon dioxide into the atmosphere.
https://time.com/4846153/ancient-rome-concrete-cement-seawater/
Science, 2017
QuoteModern concrete—used in everything from roads to buildings to bridges—can break down in as few as 50 years. But more than a thousand years after the western Roman Empire crumbled to dust, its concrete structures are still standing. Now, scientists have finally figured out why: a special ingredient that makes the cement grow stronger—not weaker—over time.
https://www.sciencemag.org/news/2017/07/why-modern-mortar-crumbles-roman-concrete-lasts-millennia