CoRncrete: A corn starch based building material (2017)

Material properties and limitations

• Mix is mostly sand with cornstarch as binder; analogy drawn to how concrete is named by binder (cement) despite being majority aggregate.
• Reported compressive strength ~26 MPa: comparable to basic “driveway” concrete but far below high‑strength structural concretes (40–200 MPa).
• Major flaw: degrades partially or completely in water within about a day. Likely needs sealing; some doubt it could ever be a general building material.
• Not fire‑resistant due to organic binder; contrasted with Portland cement’s suitability for structural, fire‑rated applications.
• Biodegradability and susceptibility to ants/rodents are raised as further concerns for long‑term use.

Environmental impact and scalability

• Several comments note that, as currently produced, cornstarch has a life‑cycle carbon footprint similar to Portland cement, so there is no clear emissions win.
• Debate over how heating energy for curing was treated in the LCA; unclear assumptions about grid cleanliness.
• Global production constraints: even diverting all corn (and its starch fraction) might not cover a quarter of current cement demand, which is expected to grow.

Potential niches (space and temporary structures)

• Water‑solubility seen as a bug on Earth but potentially acceptable on the Moon/Mars, where there’s little liquid water and starch might piggyback on food production.
• Counterpoint: importing starch to the Moon is costly; space construction research tends to prefer in‑situ materials (regolith, ice).
• Historical parallels with “staff” and other temporary materials raise the idea of deliberately short‑lived or biodegradable architecture, though safety and replacement energy costs are concerns.

Comparisons with other low‑carbon approaches

• Other pathways to decarbonize concrete:
  • Electrifying cement kilns and capturing kiln CO₂.
  • Structural design that uses less concrete (optimized beams/floor systems).
  • Alternative bio‑materials like mycelium, hempcrete, strawbale, bagasse boards, and advanced wood products, each with their own trade‑offs.

Food, land use, and biofuel parallels

• Strong concern about diverting food crops to materials, echoing earlier corn‑ethanol debates and food‑price impacts.
• Some argue there is global food surplus if waste and distribution were fixed or if ethanol corn were redirected; others stress topsoil and arable‑land limits.

Policy, economics, and greenwashing

• Many view cornstarch‑based materials as another potential outlet for overproduced, subsidized corn rather than a climate solution.
• Long digression into biofuels: multiple comments frame corn ethanol as farmer/agribusiness subsidy and “green” pretext, with government reports and propaganda cited on both sides.
• Broader skepticism toward “environmentally friendly” branding and subsidy‑driven boondoggles (e.g., solar roadways, offshore wind in some critiques).

Meta and research value

• Commenters appreciate that a peer‑reviewed paper with largely negative practical results exists; it sets expectations and makes future hype or crowdfunding schemes easier to scrutinize.
• The thread is generally glad to see experimental binders explored but treats corncrete as an instructive dead end or niche material rather than a general cement replacement.