EcoShell I – Defined
An EcoShell I is a concrete, thin shell dome whose construction process includes a relatively new technique called Airforming. This technique uses an Airform that’s made of a high-strength, high-tech fabric. When inflated, the Airform, looking like a semi-rigid balloon, creates the EcoShell’s dome shape.
The Airform used in the construction of an EcoShell I is removable and reusable. With proper care, it can be used 100 or more times, and that feature significantly lessens construction costs for projects involving more than one structure.
For an EcoShell I, concrete is layered onto the exterior of the inflated Airform. Usually, the shell is not insulated, but can be by including polystrene beads, vermiculite or perlite into some of the concrete as it’s applied. This insulation and the thermal mass of the concrete does provide some serious thermal protection.
The EcoShell I is a super-strong structure that can withstand hurricanes, tornadoes, earthquakes, fire, termites and rot.
EcoShell I – How it’s used
EcoShells have different uses. In industrialized nations, particularly those with temperate or cold climates, such as the United States, Canada and Great Britain, uninsulated EcoShells make an ideal garage, small warehouse, grain storage, shed or workshop. In other words, possibly with the exception of those living in Hawaii, an EcoShell is not suitable housing for most Americans.
But in the developing world, most of which has a tropical or equatorial climate, EcoShells can provide permanent, secure, easily maintained and – most importantly – affordable housing.
In addition to homes, people living in those areas greatly need food storage facilities, particularly for grains. David B. South, president of Monolithic and Chairman of the recently formed, nonprofit Domes For The World Foundation (DFTW), said, “Almost 50 percent of all stored food grown in developing countries is wasted because they don’t have proper storage. So rice, wheat and other foods get infested by rats and vermin. A concrete, virtually impenetrable structure could prevent much of that.”
Then too, EcoShell I construction can boost the economy of a developing nation by creating jobs. Much of the construction can be done by hand, and locals can be trained to build them.
“The building process of an EcoShell I is a relatively simple and safe one,” David said. “If a mistake is made, the EcoShell I is more forgiving than are more complex structures.”
EcoShell I – How it’s built
Monolithic has developed a booklet titled EcoShell I that illustrates and details the construction process, with sixty, captioned drawings. David said, “We already know 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 cartoonlike illustrations.” Some of those illustrations are reproduced in this article, at the end of this section. The booklet is available either as a download or purchase through the Monolithic Marketplace.
Construction of an EcoShell I 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 I has its advantages, it also has its limitations. For example, Monolithic does not recommend building an EcoShell I with a diameter of more than 40 feet (13m). Since men are working on top of 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.
See captioned illustrations Step 1A-6A showing an EcoShell I’s construction using the “flipping” method to apply Shotcrete.
Also see captioned illustrations Step 1B-5B showing an EcoShell I’s construction using a spray gun to apply Shotcrete.