Geomimetics

Mimicking the Stored Elastic Strain Energy of Rocks 

During an earthquake, rocks release stored-up elastic strain energy. How rocks store this energy depends, among other properties, on microstructure. We are mimicking the cement microstructure of fault gouges and certain seals to exploit their ability to store elastic strain energy and transform a challenge into an opportunity. The goal is to create naturally fiber-reinforced geomaterials where fibers bridge and deflect cracks, thus enhancing toughness and resistance to crack propagation before failure.

In-Situ Growth of C-A-S-H Fibers within Geopolymers

Stanford patented technology, Phlego Cement, takes inspiration from rock cementation and certain concrete-like rocks. Through a hybrid volcanic blend composition, allowing both calcium-aluminum-silicates hydrates (C-A-S-H, the glue of OPC) and potassium/sodium-aluminum-silicate hydrates (K/N-A-S-H, the glue of geopolymers) to form, we are engineering the growth of a meshwork of intertwined fibers within a geopolymer-rich matrix to prevent debonding at the matrix-fiber interface, thus avoiding a common failure mechanism in fiber-reinforced materials. (left, fibers of ettringite and tobermorite created in the laboratory, literally sprouting from a gel-like matrix).

A Geo-Inspired Cement

Just as biomimetics has yielded numerous groundbreaking materials inspired by biological structures (e.g., Velcro and gecko-inspired adhesives), we are harnessing the concept of geomimetics to engineer cement with a reduced carbon footprint, drawing inspiration from natural rock cementation and its underlying physico-chemistry. (left, our new volcanic rock blend undergoing calcination).

Reinforcing cement at the nanoscale

Active regions of Earth's crust operate akin to expansive kiln factories. Here, aluminosilicate rocks are pulverized into micron or finer particles, while internal heat channels facilitate the preparation of these fine materials for fluid-mediated reactions. Leveraging nanoscale engineering and natural conditions, we replicate these processes in the laboratory, cultivating nanofibers (seen on the right) that emulate the microstructures of rock cement. (left, cementitious nanofibers in fault gauges, courtesy of S. Siman-Tov).