“You could never get seashells and bones in the massive amounts necessary to produce enough clink to meet the demand for concrete.”
In FL the limestone is composed of crushed sea shells. The upper level of the rock is a mass of compacted shells. So you’re saying if that was heated and reduced to clink it could be used to form a new type of cement? Would be nice. Local concrete using sand and shell aggregate isn’t particularly durable, uniform or appealing.
Even so, I’m not sure that is the goal. I think they are referring to them by analogy. Seashells are much stronger and more durable than the same materials are used by humans to build. It is the microstructures and controls that need to be learned. If we can figure out ways to improve control and create these ultra strong microstructures within the materials, the product can be much stronger, durable, and lighter.