‘Rammed Earth’ Yields a Greener Block


A California R&D company has developed a high-strength, greener masonry block using one of construction's oldest processes.

Watershed Materials says its Watershed Blocks use half the cement of traditional concrete blocks, while maintaining their strength and offering an aesthetic improvement.

Watershed Blocks fuse together locally sourced materials using the ancient building method known as rammed earth.

In fact, Watershed Materials is a successor to founder David Easton's Rammed Earth Works company, which was founded in the 1970s shortly after Easton bought a 130-acre tract in the Sierra foothills and began experimenting with alternative earth construction methods.

High-Pressure Process

The Watershed Blocks manufacturing technology is patterned after the natural process that produces rock as pressure accumulates and loose soil grains are fused together into solid stone. Similarly, the company says, its factory process applies intense pressure to special soil blends of natural clays and other minerals.

Mimicking the natural process called lithification, or rock growing, the company says it uses “a precise combination of rock fragments, quartz grains, feldspars, clays, and accessory minerals and then apply intense hydraulic force to mimic the weight of 20,000 feet of sediment.”

RammedEarth Watershed Blocks

In the first generation of code-approved rammed earth (left), freestanding panels were built with site soil in reusable forms. With the third generation of rammed earth (right), high-pressure hydraulics consolidate select mineral compositions into small masonry units, dubbed Watershed Blocks.

The result, the company says, is a structural, hollow-celled “industrial stone” that is as strong and durable as concrete but consumes 65 percent less energy and is far more attractive.

The company, founded in 2011, says the process can be reproduced anywhere in the world with local soil, crushed rock and even demolished buildings.

Early development was funded in part by a grant from the National Science Foundation.

Hundreds of Projects


The company's website calls Easton "the inventor of the California forming system for rammed earth, now in use on five continents, and of the PISE [Pneumatically Impacted Stabilized Earth] method of high-pressure air installation for monolithic earth walls." The Watershed Blocks technology is the successor to the earlier processes.

Watershed Materials Watershed Block  

Watershed Blocks are made using a process called "lithification" to mimic how rock forms in nature.

Watershed Blocks have been used in commercial and residential applications, and Easton has been involved in more than 300 stabilized earth construction projects, the company says.

The company says the first home built entirely of Watershed Block in Napa, CA, sustained no structural damage during the recent magnitude 6.0 earthquake centered just miles away.

“Watershed Blocks have the visual complexity of sedimentary rock with a shape and design criteria that fit seamlessly into current masonry building typologies...,” the company says.

More information: www.watershedmaterials.com


Tagged categories: Bio-based materials; Building materials; Building science; Carbon footprint; Design; Energy efficiency; Engineers; Green building; North America; Program/Project Management

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