Mineral technology, machinery developer taps clays’ geopolymer binder potential

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One of Watershed Materials’ first high-performance masonry blocks utilizing the geopolymerization of natural clay minerals. Test samples have exhibited compressive strengths of 7,000 psi and drying shrinkage performance.

A National Science Foundation-backed building materials technology startup, Watershed Materials in Napa, Calif., reports a high-strength masonry unit production process using natural mineral-based geopolymers. Recently identified reactive compounds allow for molding universally available clays into what the company contends is a sustainable alternative to conventional concrete masonry.

“Using geopolymer technology to produce dependable building materials from natural minerals found throughout the developed and developing world is a local solution with global impact,” says Watershed Materials President David Easton.

The technology utilizes geopolymerization of clay minerals, which can be sourced from quarry and mine waste, plus construction site excavation. Geopolymers represent an alternative to portland cement; until now, such compounds have mostly relied on coal fly ash or blast furnace slag. Masonry units molded from Watershed Materials’ methods will have lower embodied energy than conventional alternatives, as they are processed without high temperature kiln cycles, and use no portland or slag cement, or fly ash binder.

When it began studying mineral-based geopolymers in 2011, Watershed Materials identified certain natural clay minerals as having properties that could be activated in a geopolymer reaction, but the process was difficult. “These minerals were overlooked by others because they are not immediately reactive as a geopolymer,” explains Director of Technology Dr. Jose Muñoz. “We’ve solved the puzzle to allow natural clays to form geopolymer bonds for the production of high strength building materials.” — http://watershedmaterials.com