An installation of pre-cast rammed earth panels at the new Stadium Techcenter in Santa Clara, California. Four panels of rammed earth are stacked on top of one another, each panel 5' high by 22' long and only inches wide. The rammed earth panels were made in our factory in Napa, California and transported to the job site where they were installed on site.
Image © Michael David Rose
This particular installation could not have been accomplished with traditional methods of monolithic rammed earth in which 18" thick walls are rammed on site - lots of material is needed and large formwork is constructed. In this case, the job site couldn't accommodate the construction of traditional monolithic rammed earth.
The team at Rammed Earth Works has continued to innovate rammed earth technology for 30 years, and the development of pre-cast rammed earth panels is one of the most exciting developments yet. It allows for installation of rammed earth in more applications, and can lead to a lowered cost.
Here are nine pre-cast rammed earth panels in our factory in Napa, California, waiting to be sawn to final dimensions and transported to the job site for final installation. A steel frame is installed on the back of each panel to use for attachment to the structural wall.
The rammed earth pre-cast panel system is opening up an exciting new opportunity for us at the studio - the art of rammed earth. We take advantage of all the things we’ve learned over the years, and squeeze them into a wall with a three-inch thick profile - the beauty without the bulk. This means rammed earth can be used in locations previously considered too difficult or too expensive. The image above is a detail from the new Big Sur collection to be installed in the spring of 2017. The wall colors drift from taupe to wheat with two thin strata bands, one rice ash and the other lime and Olympic sand.
These pre-cast rammed earth panels are 3-4 inches thick and are ideal for non-structural applications for projects that don't have the available footprint for traditional on-site rammed earth walls that can often range from 18-24 inches thick. Rammed Earth Works is able to produce these panels at our factory at much higher volume than on-site installations with custom one-off formwork. Rammed Earth Works is able to take advantage of re-using formwork as well as the factory environment to speed production time.
Measuring five feet high by twenty-four feet long, each of the 3” thick panels weighs 4,200 pounds when fresh out of the mold - 3,850 pounds once the hydration water is converted. What keeps them together? Ultra high compression.
An overhead view of a panels being rammed in the form.
Each five-inch loose lift takes one minute twenty seconds to deposit into the formwork. Target density is 136 pounds per cubic foot. A Jet 2-T rammer has a tool weight of twenty-one pounds, works on 90 psi of air pressure, and has a strike rate of 700 blows per minute. To reach 97% compaction rate, the rammer travels along the twenty-four foot long wall at the same rate as the delivery conveyor - three linear feet every fifteen seconds.
The precast rammed earth panels are taken directly off of the delivery truck and lowered into place either against an exterior wall, or as in the case of our Menlo Park project, through the roof framework and into place along the stairwell, fireplace, and dining room. Menlo Park was challenging, especially for our first big residential panel project. In crane setting terminology, each lift is called a “pick”. The crew managed anywhere from five to twelve picks per day.
For the installation of the four big Stadium Techcenter panels, we used a long reach forklift to set the panels rather than a crane because the roof was already on the building. The forklift picked each of the twenty-two foot long by five foot high panels off the truck, backed directly into the lobby with only eight inches of space between the door frames and the panels, executed a ninety-degree turn and placed the panels one on top of another against four steel wide flange posts where they were welded in place.
Another way to deliver precast rammed earth panels uses manpower to go right through the front door, especially useful when there’s no room for a crane or a forklift. We built a portable jib crane to move each 2,000 pound panel from the trailer to the sidewalk and we built a six-wheeled trolley to roll the panels into the store. As you can see, it took three people pushing and one pulling to get the panel up and over the door threshold. The rammed earth arrived safe and ready for installation in a retail store that could have never used the material with traditional on-site form setting methods.