Here’s a natural substitute for steel rebar. It seems like this material would work perfectly with earthbag building, especially in seismic areas where additional reinforcing is typically required. Image and content below is from the Smarter Building Systems website.
“Zeebars Basalt Rebar is an alternative to steel and fiberglass for reinforcing concrete. Made from volcanic rock it is tough, stronger than steel and has a higher tensile strength. Much lighter than steel, 89% percent in fact! One man can easily lift a 500 foot coil of 10 mm rebar.
Zeebars are naturally resistant to alkali, rust and acids. Moisture penetration from concrete does not spall. Zeebars need no special coating like fiberglass rods. The same thermal coefficient expansion as concrete!
Allowing thinner, lighter panels and decks, Zeebars reduce the thickness and spacing between the rods and the concrete and surface. Much more flexible design! Smaller rods allow for more critical spacing and designs. Zeebars are easily cut to length with regular tools.
Basalt rebar does not conduct electricity or induce fields when exposed to RF energy, great for MRI or data buildings. Zeebars are perfect for marine environments and chemical plants where corrosion is a continuous concern.”