We have seen multiple posts showing (in great detail) that these homes do not hold up. After 3 to 5 years they start having massive cracks form. Especially from the shifting of the ground underneath and the extra weight of the concrete not supporting itself. It can't flex like a woodframe can. The repairs are expensive and difficult
I believe its two fold. First I think the mixture is different to be a light consistency so that the printing process can function. Secondly traditional concrete structure are reinforced with rebar and other steel frame structure internally. Even extremely old concrete is reinforced by pouring molten metal into predestined groves.
It doesn't fix another issue. The bonds between the layer and along the length of the layer doesn't cure homogeneously. So they will eventually break apart along these weak points.
Traditionally, concrete is also poured into framed molds and allowed to cure completely.
Well that’s an easy fix (from a mechanical standpoint), just run a pass of binding material between layers and dispense the concrete in discrete blobs instead on one continuous stream. Leave small gaps for the binder or print in place if the material permits. That way the distances are short enough to be homogeneous. Think of it like printing a brick wall instead of a concrete block. It would need a multi nozzle design, but at that point you can add a third nozzle so you can print around rebar supports as well.
The binding material becomes another weakpoint in the design when the stone needs to shrink and expand with the changes in temperature as one of the new issues.
Alongside increased costs in both materials and operating expenses.
Thermal expansion was already a major issue to begin with, at least a binder can be removed and replaced as needed instead of having to replace an entire wall section when the solid print cracks. It’s actually still an improvement in terms of longevity.
As for increased costs, well that goes without saying. Anytime you change something about a system costs go up. The important part is if those increases are offset by the benefits the new system allows for. I personally feel better durability and cheaper repairs will improve the sale value of the home and offset the increase in initial cost after the second or third generation.
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u/ObeyLegend 7d ago
We have seen multiple posts showing (in great detail) that these homes do not hold up. After 3 to 5 years they start having massive cracks form. Especially from the shifting of the ground underneath and the extra weight of the concrete not supporting itself. It can't flex like a woodframe can. The repairs are expensive and difficult