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April 19, 2014  |  Login
Pneumatically Impacted Stabilized Earth
By Eric Corey Freed
A refinement of rammed earth, pneumatically impacted stabilized earth (PISÉ) creates a beautiful wall made of only natural and healthy materials. PISÉ shares the beauty of rammed earth but is much less labor intensive.

What Pneumatically Impacted Stabilized Earth Is

Technically, PISÉ is a type of rammed earth. A mixture of mud and cement is packed into a form. Rammed earth requires you to build formwork into which you pack earth, and PISÉ improves on this process. With PISÉ, you only build one side of the formwork and spray the earth into the form. PISÉ offers all the environmental benefits of rammed earth, but with a much shorter construction process.

The History of PISÉ

In the late 1700s, Paris builder Francois Cointeraux created a school dedicated to the study of rammed earth construction. Called pisé de terre, it translated to “puddled clay of earth.”

Nearly 200 years later, author and rammed earth pioneer David Easton developed a new version of rammed earth construction, which he called PISÉ in honor of the old French school. Instead of tamping the earth into a form, Easton realized he could use a high-pressure spray gun to shoot the soil into the mold.

This spray technique is four times faster than traditional rammed earth. By reducing the labor, you also reduce the cost.
A one-sided form is placed over the building foundation. Think of it as an open-faced sandwich. A watery mixture of earth and Portland cement (3%) is sprayed through a pneumatic (pressurized) spray hose into this form. This method is the same one used to form swimming pools.

The mix is light and sticky enough to adhere to the side of the form without slumping. The PISÉ mix is sprayed in 2- to 3-foot-high layers and left to dry. In 30 minutes to an hour, another layer is added. Unlike rammed earth, the form must be left in place for a few hours until the PISÉ dries.

The single-sided forms are easy to set up and take down, and can be reused over and over again. The open face makes installing plumbing and electrical conduits, as well as adding steel reinforcing for earthquake resistance, much easier.

In case you’re wondering why anyone would still use rammed earth if PISÉ is so superior: PISÉ requires specialized spray equipment and can’t be installed by the typical homeowner. Also, although PISÉ is attractive, it lacks the wavy colors of a rammed earth wall.

You can apply plaster directly to the face of a PISÉ wall to finish it, although the exposed surface has a beautiful look. Finish the walls with a natural linseed oil instead.

The strong PISÉ walls are superior to traditional wood framing. They are resistant to fire, rot, and insects.

Taking Advantage of Pneumatically Impacted Stabilized Earth

PISÉ buildings work in most climates, including damp areas with cold winters. more



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