MORTAR EXPERIMENT
Mixed: Saturday, April 2nd, 2005
In search of a strong mortar to make a thin shelled (½")
wall and roof material for the planned Faerie Hill Ecoark I made 8 test samples of various mortar mixes using powdered ingredients mixed with enough water to make a thick paste in a plastic yogurt cup. While mixing it was clear that the samples
containing a higher percentage of clay were much creamier in consistency (a good thing when spreading over large areas).
I used an orange-red clay from the Faerie Hill excavation and a white fine mortar sand. The lime is dry hydrated and the Portland cement is a standard mortar grade. Water is tap.
Each mortar sample will be allowed to cure for 1 week at
which time I'll provide basic test results:
#1: 1 part clay, 1 part sand, 1 part lime, 1 part portland
#2: 2 parts clay, 2 parts sand, 1 part lime, 1 part portland
#3: 2 parts clay, 2 parts sand, 2 parts lime, 1 part portland
#4: 1 part clay, 2 parts sand, 1 part lime, 1 part portland
#5: 1 part clay, 2 parts sand, 2 parts lime, 1 part portland
#6: 1 part clay, 3 parts sand, 2 parts lime
#7: 1 part clay, 2 parts sand, 2 parts lime
#8: 4 parts sand, 2 parts lime, 1 part Portland
note: None of these samples contain any reinforcing fibers
which, when used in thin shelled walls and roofs, are highly
desirable and provide much greater strength and prevent
cracking., I left the fibers out of the samples in order to
test the mortars in a non-reinforced "worst case situation".
LONGER TERM RESULTS
Friday, February 2nd, 2006
The test samples above have now laid outside in their open
topped recycled yogurt cup containers for 5 months, fully
exposed to the weather - including many freeze-thaw cycles.
Each sample had a wooden popsicle stick inserted in the top
of the sample while the mix was wet. Here are the results:
#1: minimal fine-grained top/exposed surface fragmentation, hard uncracked cylinder mass, stick firmly implanted - excellent strength and durability rating - I would dare to use it in an outdoor stucco or casting application
#2: considerable exposed surface fragmentation/flaking up to ½" into the sample, uncracked cylinder mass below the fragmentation, stick firmly implanted - I would not recommend building anything exposed to the weather with this but it might make a nice reddish internal plaster
#3: same as #2 but surface only fragmented to ¼" and that was along the edges rather than the whole surface as in #2
#4: medium level of exposed surface fragmentation to a maximum depth of 1/8", hard uncracked cylinder mass, stick firmly implanted - I still wouldn't recommend it for outdoor exposure
#5: minimal exposed edge chipping to a depth of 1/16", very strong uncracked cylinder mass, stick firmly implanted - I'd use it outdoors with reservations
#6: complete soggy sandy mush, dissolution of all primary bounding - worthless as a building material
#7: same as #6 - worthless
#8: not much better than #6 and #7 although there is some adhesion in the mass and the particles are in flakes rather than like sand as in #6 and #7 - worthless
Conclusions: High clay and sand based mixes are unstable without the addition of Portland cement to the mixture.
Clay/sand mixes require at least 50% of the mix to be a lime/Portland combination. The strongest test sample was #1: 1 part clay, 1 part sand, 1 part lime, 1 part Portland.
The next strongest was #5: 1 part clay, 2 parts sand, 2 parts lime,
1 part Portland.
note:
Besides the above mentioned samples I also weathered a series of chopped recycled Styrofoam/Portland/sand/lime mixtures, all of which show no visual adverse effects to the exposure, seemingly retaining complete structural integrity and actually
appearing to have become stronger in time. This includes the ones with the highest concentration (50%) of Styrofoam.
Suggestion:
I would love to see a series of test samples cast with the addition
of wet sawdust and/or other waste materials. Anyone game?
Terry Ryan Kok
biostar_a@yahoo.com
http://www.magickmonkey.com
http://groups.yahoo.com/group/andorprojex
posted by noobs @ 11:45 AM
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