local sustainable bldg materials and methods?

[Ccat]

I contend it’s aircrete, and more specifically, the lack of tensile reinforcement that leads to cracking. It all comes down to the concepts of compression and tension. Domes, all domes, have areas that are under compression (mostly), and tension (usually halfway up). Concrete has lots of compressive strength, aircrete less so, but still enough not to pulverize under it's own weight, but neither of them have much in the way of tensile strength. If you don't have any tensile reinforcement, it's going to crack in the areas under tension. So, yeah, it's part of domes in general, but easily solved by incorporating reinforcement. But aircrete constrution using blocks makes that nearly impossible to incorporate in the aircrete itself. Reinforce the blocks, and the cracks will just move to the joints between the blocks.

I saw Domegaia recently made a arched structure, like a quonset, out of aircrete, and coincidentally made the shape that of a inverted cantenary, like the St Louis Arch. Very good reason for this. That shape has almost zero tensile forces, it exists in perfect compression along the entire shell.

Were I to build anything with aircrete, I’d cover it with some basalt or fiberglass mesh and apply some mortar. By then it would have just been easier IMO to build a dome with rebar in it to begin with.

I think on this often, and it's really hard to beat the utility and especially the speed and ease of construction of a concrete dome built using conventional redi-mix delivered concrete, concrete pump, and shotcrete application. Yes, you need a lot of equipment to do it this way, but you can get the whole job of concrete application done in an hour.

What do you think about adding fiber to the mix?  Does that really solve the cracking problem?

Ccat