Construction of an EcoShell begins with a small group of workers pouring a circular floor, to which the Airform is attached 2 inches in from the edge. The Airform is inflated with a small, high-pressure fan, such as fans used for heavy duty vacuum cleaners. After the Airform is inflated, rebar and then concrete are applied over its exterior.
The concrete can be mixed in a bucket or a fabric mixer and hand applied, or it can be mixed with commercial mixers and sprayed in place with Shotcrete equipment. This latter method obviously takes less manpower and at times produces better results. But the former method is also satisfactory and can be completed by inexperienced laborers.
Once the concrete sets, the Airform is removed.
When the EcoShell is to be used for bulk storage, the engineer must calculate the amount of side wall pressure and a corresponding increase in rebar must be added. In addition, there are several products available to add to the concrete mix that reduce cracking and increase concrete quality.
Since the EcoShell is generally not insulated, it won’t be climate controlled, but its concrete does have some thermal value. And it can be covered with thatching, straw or dirt for insulation. Its roof can be coated with aluminized asphalt or a high grade exterior paint, preferably white to reflect heat. Recently we have added a layer of concrete that has polystyrene pellets, or vermiculite, or perlite added to it for insulation. Click here to see video explaining this process.
While the EcoShell has its advantages, it also has its limitations. For example, Monolithic does not recommend building an EcoShell with a diameter of more than 40 feet (13m). Since men work atop an Airform there is always a risk to them of sudden collapse.
All things considered, the EcoShell is one of construction’s strongest buildings. It is virtually impervious to fire, tornadoes and earthquakes. It is especially practical in countries lacking wood and steel. Most countries have concrete and rebar on hand. In general, using the same amount of cement, aggregate and rebar, three EcoShells can be built in place of one conventional, concrete structure.
Monolithic has developed a booklet titled EcoShell I that illustrates and details the construction process, with sixty, captioned drawings. DFTW already knows that most workers — even those who cannot read or speak English — can catch on to how something must be done by studying this booklet’s cartoon-like illustrations. The booklet is available as a download.