[Cob] re Next Step (Janet Standeford)

[Kathy Dunster]

He was looking at low-cost housing alternatives for survivors of the 2006
tsunami in Sri Lanka, obviously seismic stability is important in that
region.

Direct link to the full 182 page Daigle thesis is

http://www.earthbagbuilding.com/pdf/Daigle_Bryce_C_200809_MScEng.pdf


"It was determined that the compressive strength of *unplastered* earthbag
housing specimens meets or exceeds the vertical compressive strength of
conventional stud-frame housing technology using a variety of fill
materials, with the greatest strength being observed for soilfilled bags."

Note "unplastered" as he concludes more work needs to be done on plastered
earth bag buildings as in a good shake the plaster would probably fall off,
but would not compromise the integrity of the building's structure.

He also concluded that

1. "Stack height affects the strength and stiffness of earthbag specimens,
with taller stacks (i.e. 6 or 9 bags) exhibiting lower strength and
stiffness values, as well as different load-deformation behaviour than
shorter stacks (i.e. 3 bags)."

2. The testing procedures outlined in ASTM E 447 are inadequate for testing
earthbag specimens due to their reliance on 3-unit stacks which may
overestimate compressive strength.

3. Soil-filled bags measuring 457 x 762 mm require loads in excess of 840
kN to reach bag failure (defined as a loss of fill leading to reduced
compressive load-bearing capacity). This is also true for soil-filled bags
measuring 508 mm x 914 mm.


-------------------------------------------------------
Kathy Dunster
Denman Island, B.C. Canada