New Rock-Based Blocks Stronger, Less Polluting than Concrete
Napa-Valley startup Watershed Materials has created a natural masonry that's twice as strong as concrete (7,000 psi).
Partially funded with a National Science Foundation (NSF) grant, Watershed Materials announced this August that they have developed a form of concrete that is far less CO2 intensive than Portland cement-based product. They're using half the normal Portland Cement to make a masonryl product called the Watershed Block. The new material also contains no fly ash or blast-furnace slag. The company describes the process as “geopolymerizing naturally-occurring clay minerals,” which are found abundantly worldwide.
Watershed Materials' is being purposely vague about the exact process of creating the mix, concerned that they may lose their market edge
"Our technology unlocks the strength in the minerals all around us—limestone, granite, rhyolite," they assert. "Rock forms in nature over the course of millions of years as pressure fuses loose grains into solid stone. Watershed Materials has developed technology to activate this process in seconds rather than millennia."
“The implications for this technology are enormous,” says David Easton, Watershed Materials’ president and co-founder. “Using geopolymer technology to produce dependable building materials from natural clay minerals found throughout the developed and developing world is a local solution with global impact.”
Geology and Geopolymer Merge
Watershed Materials first began to study mineral-based geopolymers as an alternative to Portland cement in 2011. The company identified certain natural clay minerals as having properties that could be activated in a geopolymer reaction, but the process was difficult. The NSF has given the company two grants that according to its grant Website total $742,872.00.
“These minerals were overlooked by others because they are not immediately reactive as a geopolymer,” says Dr. Jose Muñoz, Watershed Materials’ director of technology. “We’ve solved the puzzle, to allow natural clays to form geopolymer bonds for the production of high strength building materials.”
Dr. Muñoz and Taj Easton, Watershed Materials’ research lab manager, spent four years refining their geopolymerization process. “The masonry produced with this technology,” they write, “uses less energy to produce, requires no-high temperature kilning, incorporates no dyes or colorants, and will open up previously overlooked, widely available natural and recycled materials."
Watershed uses "a precise combination of rock fragments, quartz grains, feldspars, clays, and accessory minerals." Key to resulting block strength is the next step—the application of "intense hydraulic force to mimic the weight of twenty thousand feet of sediment." The hydraulic press is pictured.
David Easton's Back Story
Easton is no stranger to natural building with earth. Many call him a pioneer. He founded Rammed Earth Works in 1976 and is the author of The Rammed Earth Experience (1982) and The Rammed Earth House Second Edition (Chelsea Green 2007).
Easton has been an innovator in rammed earth, one of the most ancient building materials on the planet. His company developed pise (pneumatically impacted stabilized earth). The method shoots the material, (much as you would gunite) against a single wall, rather than a boxed form. Other rammed earth builders, typically use smaller forms, and may or may not pump the earth into the form. Easton’s technique results in faster walls, though he sometimes combines techniques. His Website says, “Plan on one six-inch lift every twenty minutes, a foot and a half per hour, twelve feet in an eight hour shift.” Watch the video below to understand the similarities and differences in the variety of methods Easton uses to build earthen walls.
Indigenous, local, strong
There is ancient history in building with earthen material whether as mud or dried and/or fired into brick. The clay-based geopolymer will help people not only in developed but also in developing countries produce “durable building products from locally sourced clay materials.”
Masonry is heavy, thus local production in addition to non-polluting materials will increase the materials’ green effect. Another benefit is that natural variations in regional clays and aggregates create uniquely indigenous masonry and buildings.
Raw materials can be from recycled mine and quarry dust and aggregates. Cutting slabs and blocks of stone creates a lot of waste. In ages past, the material dug out for basements became adobe building blocks as was true in a mud adobe home I once owned in Tucson; geopolymer technology can resurrect these practices. Demolition material can also be a prime candidate to create the durable masonry giving another meaning to the old cliche, “waste not, want not.”
Watershed Materials expects their technology to be useful in places where there is a lot of debris and a need for new buildings following a natural disaster.
Here are details about the National Science Foundation Grant.
Find out more at Rammed Earth Works.
This presentation of a lecture by David Easton on rammed earth and the new Watershed Blocks. "Earth or soil—dirt is what is under the refrigerator," Easton says.
Enjoy this YouTube video of artist Andy Goldworthy's Earth Wall—it explains from an artistic perspective the appeal of natural materials.: