Open Weave Fabric: Ideal Working Properties

I was able to find some fruit and vegetable bags that seem to match what is being used in Brazil by Fernando Pacheco, the developer of the Hiperadobe earthbag system. What I’ve located is an open weave synthetic fabric, 5 x 10mm weave with 2 x 8mm openings. It has vertical threads and horizontal strips of fabric. They’re called raschel mesh bags or raschel bags in the industry. (Google those terms for lots of photos and details.)

My initial impressions are very favorable: extremely tough, no ‘give’ or stretch when pulled by hand and no sign of tearing during tamping. It has ideal working properties for earthbag walls in virtually every regard. In addition, the material looks almost identical to shade cloth that’s used to shade plants in nurseries and plant stores except it lacks the glossy coating. More testing is needed to determine its ultraviolet (UV) resistance.

Amazingly the 16” x 32” open weave bags expanded slightly to about the same width as standard earthbag walls once filled and tamped: 14-1/2” for open weave in comparison to 15” for poly earthbags. And the openings are just the right size so there’s virtually no spillage with our clay/aggregate road base mix. (The clay clumps the aggregates together like glue.)

So now we have another standard, commercially available product that works perfectly either by itself or in conjunction with poly bags. This to me is a game-changer, folks. Anyone sitting on the sidelines can now use this improved system to reduce costs and labor, and speed construction. I encourage everyone to buy a few bags and test this out. Your results may vary. We’ve already had one report of very weak vegetable bags.

Summary of benefits:
– Final wall thickness nearly identical to poly bags (about ½” narrower)
– Negligible spillage (maybe 1-2 tablespoons of dry crumbs fell through the bag)
– Excellent strength – perfect for earthbag building
– The rough texture creates more friction between courses, thereby eliminating the need for barbed wire on vertical wall designs (non-seismic areas only)
– Improved bonding with barbed wire if it is used (they’re drawn together almost like magnets and are difficult to separate)
– Enhanced bonding with plaster (it’s as if the bags are wrapped in plaster mesh)
– The open weave fabric is made with less material (about half as much), which lowers its environmental impact
– The bags are probably less expensive, because the merchant at the farmer’s market sold me the bags at less cost than poly bags, even though they were in perfect condition. I’ll report on the cost once I find the supplier.
– Much faster drying (noticeable drying in just one hour in the sun)
– More monolithic structure due to direct bonding between courses
– Standard, readily available product that’s sold locally as bags
– No doubt the same size tubes are available (bags are cut from tubes), which would speed wall construction
– Possibly greater UV resistance (yet to be verified)
– Ease of filling and handling: the fabric readily slid onto the end of a bucket chute and bunched up nicely (less stiff than poly bags)
– They handled almost exactly the same as poly earthbags (same skills can be used for both types of bags)
– No protruding corners

Both Kelly Hart and I see this as a major development for earthbag building. The only drawback we can think of is some loose fill material like sand, rice hulls or crusher fines will fall out of the openings.