The following information has been graciously provided by Dr. Johnny Anderton of Eternally Solar / EarthBagBuild. Their building system is described below. It’s obviously another huge step forward in earthbag construction, right up there with Hyperadobe, Reinforced Earthbag and Superadobe.
“The way the bag is stitched divides it into 3 tubes – only the outer 2 are filled, creating 2 sausages joined by the central flat web (the third central ‘virtual’ tube). In building a wall, earth is poured into the central channel created by these 2 tubes and with the next layer, another bag is draped over this ‘mountain range’ and the central web compacted down to flatten the earth below it.
[Note by Owen: The center area creates a spline that strengthens the wall more than just bags on top of each other.]
• The bags are all equally filled, no chance of great variation in filled volume as with a large bag.
• Each ‘lift’ is approximately the same height
• Very easy to lay with no previous experience, as the bag essentially takes its shape while it is being filled.
• The bags are not heavy to move and can be prefilled before construction commences
• Plastic on plastic between rows is limited to the area along the length of the tubes, but the compacted ‘fillet’ of earth in the channel, locks the upper bag to the one below it. So no slippage and no barbed wire needed. Yet the actual amount of polyprop bag material is more or less the same.
• The length of the bag in its filled state in the wall @ 750mm is long enough to create a strong overlapping running bond between rows.
• The channel can be filled with cement and rebar, to create very strong lintels, ring beams or other horizontal stiffening members (we’ve tested lintel spans to 3 metres, by using the cement and rebar in 4 successive layers, way surpasses the strength required by local building codes).
“What is special about our EarthBags, what are they made of and how long will they last?
The bags are a unique patented design that allow for interlocking of horizontal layers greatly adding to the stability of the wall. This design also allows for accurate and equal filling, relatively low mass at approximately 13kg, uniform horizontal layering in the wall, easy construction of integrated lintels and ring beams and laying of conduits both vertically and horizontally.
All of these advantages are reasons the EarthBag is made the way it is. Using a standard polypropylene fertiliser bag, it is possible to construct a wall, but the ease of build, the end result and the ultimate strength are all very adversely affected. For example, the bag will be very heavy and therefore needs to be filled in place on the wall, it is difficult to fill every bag to the same degree, and to get the bags to lie symmetrically takes experience.
Furthermore, with a standard bag, one bag lies directly on the one below, plastic on plastic, with minimal lateral stability, and increased chance of slippage. Barbed wire then has to be used to ‘velcro’ the layers together. Using sand alone with these bags is not a good option, so stabilising with cement or using a clay-earth mixture is required.
As an example of how the system will slash the cost of transport in a major construction project, sufficient EarthBags to build the walls for two hundred and fifty 40m2 houses, can be transported in a standard 12 metre shipping container!”