- 1 research
- 2 Geopolymer formulas (alumina-silcate cement)
- 2.1 Tungsten mine study
- 2.2 Notes
- 2.3 Davidotas video formula
- 2.4 comparative building material compressive strengths
- 2.5 FROM LIMESTONE TO LIME, AND BACK...
- 2.6 Indian Fly ash bricks
- 2.7 geopolymers
- 2.8 Elliot Hallmark's GP goop
I've spent probably more than 40 hours this past year researching geopolymers. I've put together an unedited jumble of formulas. I'll post them below. Eventually I'll make this all article-worthy, but for now, data-dump. (I bought a lot of raw ingredients in November but have been lazy and haven't made any test bricks yet.)
Geopolymer formulas (alumina-silcate cement)
Tungsten mine study
Here's what I could make out from this study which uses "waste mud" from a mining operation as the active alumina-silicate pozzolan (fly ash, volcanic ash, powdered slag, silica fume, and metakaolin are other examples of pozzolans).
parts by mass: 15 parts aggregate (powder from schist, limestone, or granite) 9 parts waste mud (dried pozzolan) 1 part hydrated lime 10 parts activator:
- 2.85 parts NaOH (24 Molar lye flakes) - 7.15 parts Na2SiO3 (probably neutral grade, "Na2O=8.6%, SiO2=27.8%, Al2O3=.4%, H2O=63.2%")
Distilled water, unknown quantity:
- Enough water supposedly added to dissolve lye flakes - Then enough water to make concrete paste workable - Perhaps between 3% and 10% weight of waste mud component (would mean from 1/3 to 1 "part" above)
0. Calcine (heat) the waste mud pozzolan to 800*C for at least 30 minutes.
1. In one vessel, mix 15 parts aggregate with 9 parts waste mud pozzolan
2. Mix in 1 part hydrated lime. This is the "active binder and inactive aggregate".
3. Mix in enough water to a consistency of "barely moist sand".
4. In second vessel, mix some water with 2.85 parts lye flakes.
5. Mix in 7.15 parts sodium silicate with dissolved lye. This is now the "alkali activator".
6. Pour alkali activator into binder+aggregate, mix thoroughly.
7. Add up to 1 part water to make the mix reasonably workable/castable. You now have a geopolymer mortar.
8. Pour and tamp geopolymer mortar into a mould.
9. Remove from mold after 24 hours.
Despite some high-school level chemistry documentation errors made in this study, it is one of the best geopolymer studies I've read. A rewrite of this same study by the same authors, "Geopolymeric binder using tungsten mine waste", (cited in google book id=wIFo7L_zO8AC, isbn=9782951482005) is even better.
The pozzolan used is "calcined" to begin with -- heated, to drive off chemically-bound water. It's not clear whether this is actually necessary or just speeds up the mortar set time. NO CONTROL with un-calcined "waste mud" was prepared for this study! It's probably possible to substitute in recently-harvested fly ash or silica fume for this waste mud and you'll still get a geopolymer. The authors note that the molar ratios between lye and water glass (sodium silicate) and water are not optimized, and that you can stray a little bit from this recipe without anything going wrong. Stray too far and you'll get a fluid that won't set or a mortar that will flash set in less than five minutes.
This mortar has an open time (that is, window of opportunity for casting) of perhaps less than an hour, and will harden to beyond the strength of a brick in 24 hours or less. It will reach near-maximum compressive strength in less than 10 days. At 20MPa, the strength of the weakest mix in this study is equal to that of normal portland cement mortar.
It appears that this mortar was allowed to set and cure at room temperature. Good! So many of these ridiculous geopolymer studies specify curing temperatures of 40*C, 60*C, or higher (totally useless for normal building applications).
The lye and sodium silicate cost too much money for this geopolymer mortar to compete with portland cement (1.5 to 2.5 times portland cement mortar cost). However, the authors did not attempt to optimize cost in any way.
This is perhaps the first clear geopolymer recipe available for free on the web! Hooray!!
Davidotas video formula
Dry ingredients: - large pile of crumbly fossil-rich kaolin-poor limestone (from France) - lime (hydrated lime) - natron (from France) - kaolin clay
Quantities: - Roughly 1 cubic yard (1 ton) limestone aggregate - Roughly 1 cubic foot kaolin - Roughly .5 cubic foot natron and hydrated lime - 130 gallons of water
Rough ratio: 27 : 1 : 0.5 : 17 ... limestone:kaolin:natron+lime:water
- Measure out water
- Pour in natron and hydrated lime
- Pour in kaolin
- Mix to yield white milky fluid
- Pour in limestone aggregate
- Mix thoroughly
- Let sit several days in full sun, French Mediterranean summer
- Excess water evaporates
- Yields friable "disagglomerated" material like moist lumpy sand
- Note: looks nothing like a "slurry" at this point
This is said to be: - 95% limestone aggregates - 5% rock-making binder - 12-17% water content, consistency of wet sand
- Set up wooden form with volume roughly one-half cubic yard
- Pack crumbly moist cement into form with rammer
- Remove mold 4 hours later
Quotes: "in-situ geologic glue" "In this ideal weather, the whole process runs smoothely and is very simple." "When the climate is warm and beautiful, our crew rapidly produces a reagglomerated limestone that proved strong, dense, and true to the planned size and shape."
Notes: Video is unclear on natron versus sodium carbonate. They are not the same thing. Exact quantities of kaolin, natron, and lime are not given. Exact time of lime (hydrated? putty? quick?) is not given. No other ingredients are mentioned (magnesium compounds? carnallite?). Initial mixing-in of limestone aggregates is not shown... is it covered in water that evaporates, or does it completely absorb the water and then sit? Limestone used appears distinctly pebbly and crumbly, lightly tan-colored, not "shale"- or "stone"-like. Video appears to show this concrete being used to form a rough-surfaced, dry-looking block that reagglomerated like moist bread flour being smashed into a clod. This is build atop a stone where it is suggested that more water was used to produce a higher-resolution, perhaps runnier casting slurry.
comparative building material compressive strengths
adobe, cob 150 to 200 psi Rammed blocks 350 to 400 psi concrete block 2000 psi baked brick 4000 psi concrete 6000 psi granite stone 15,000 psi steel 25,000 psi Wood 10,000 psi. Soils 50 to 70psi. earth wall 1.5 feet wide 43,000 lbs per linear foot concrete block 8 inches thick 191,000 lbs per linear foot earthship tire wall (3 foot thick) 100,000 lbs per linear foot
FROM LIMESTONE TO LIME, AND BACK...
CaCO3, MgCO3 LIMESTONE + HEAT = CaO, MgO
QUICKLIME (ASTM C5)
CaO, MgO QUICKLIME + H2O
WATER = Ca(OH)2, Mg(OH)2
HYDRATED LIME (Stoichiometric Water) ASTM C207 or LIME PUTTY (Excess Water)
HYDRATED LIME or LIME PUTTY + GRADED SAND
(ASTM C144) PORTLAND CEMENT (ASTM C150) = MASONARY MORTAR (ASTM C270)
Ca(OH)2, Mg(OH)2 LIME IN MASONRY MORTAR + CO2
CARBON DIOXIDE = CaCO3, MgCO3 LIMESTONE
Indian Fly ash bricks
Fly ash, Hydrated lime, Quarry dust and gypsum are manually fed into a pan mixer where water is added in the required proportion. 62% fly ash 8% lime 5% Gypsum 25% sand or Quarry Dust
mixture is pressed in hydraulic Brick Making machines. bricks are carried on wooden pallets open area dried and water cured for 14 days.
20% fly ash 15% lime 5% Gypsum 60% sand or Quarry Dust
? parts Kaolin Clay (from China) 1 part natron 4 parts lime 12 parts sand
"works good very and becomes really solid"
preprocessing is not necessary, 8-10% clay, can be rich in silt diameter of gravel up to 5-7cm
Ingredient/% by Weight Soil/100 Gypsum/10 (15% according to Wiki, but Turkish site says 10% is most efficient) Lime/2 Water/18-20 (According to the dryness of the soil) (Practical measures in the same order as above: 2 full wheelbarrows, 4 shovelfuls, 1 shovelful, one bucketful.)
Traditional earth construction 15-21 days strengthening curing area water sprinkling rain protection
Alker construction 20 min. strengthening no curing area no water sprinkling no rain protection (work can continue in the rain)
The production of alker starts by mixing lime in the water firstly and gypsum secondly. This heavy water has to be poured onto soil and mixed mechanically about 3 minutes (by hand a little longer). Mechanical mixing or hand mixing both work.
Start with pool of water and then add: Quicklime (limestone calcined at 900 degrees C.) Diatomaceous earth Powdered/crushed limestone Mix and wait a few days to allow water to evaporate
At this point the limestone ‘mud’ is placed in earthbags or wood forms. Dr. Barsoum says sand was not used because it does not dissolve and so it’s not part of the chemical ‘glue’ that binds the other materials together.
Prasad and Shahoma McAlister
Geopolymer cement notes. The making of alkaline solution:
- 12 hr before mixing, slowly! dissolve 320gm sodium hydroxide (pure lye, as in a drain cleaner) into a liter of water. This should be stirred in slowly, with care, wearing gloves and goggles as it is very caustic. This mix will generate some heat while dissolving.
- After the lye solution is fully dissolved (12hr) mix one part lye solution with 2 1/2 parts sodium silicate. (available at pottery supplies)
- Basic recipe #8
4 1/2 parts metakaolin [Ed.: heat treated kaolin] 1/2 part lime (type-S) 8 parts aggregate (sand mix) alkaline solution as needed (about 1/3 the amount of metakaolin and ash, by weight)
- Mix all the dry ingredients together then stir in just enough alkaline solution to make a stiff mix. Keep the liquid content as low as possible. Cure like concrete, warm and moist.
- Class C fly ash can replace the metakaolin and lime, if its type F fly ash replace only the metakaolin.
Geopolymer concrete negates the need for Portland cement as a binder. Instead, materials such as fly ash are activated by alkaline liquids (most often at temperatures below 150 degrees Celsius) to create the cement.
Elliot Hallmark's GP goop
1) silicate solution "A"
Need: - 500g soldium silicate (Na2SiO3) [water glass, sodium metasilicate, SS40] - 136g sodium hydroxide (NaOH) [lye, caustic soda, drain cleaner] - tough pyrex + stirstick - sealable glass jar - water bath
In pyrex, add SS40, then pour in NaOH pellets. Gets very hot. Stir to yeild homogenous cloudy white solution. Relax a few minutes. Transfer to glass jar with a lid. Immerse in water bath several hours until solution is clear. Check that water bath doesn't evaporate. That's it!
Note: Reheating and stirring will redissolve precipitate that may form if solution sits around for days.
2) GP binder "B"
Need: - 600g silicate solution "A" - 505g metakaolin (calcined kaolin) - 128g water you hosers - nonreactive mixing vessel
Mix really well, with mixer, 5-10 minutes. Let sit for 1-2 hours.
3) Mix in aggregate "C"
Need: - 320g silica flour ("Micronized a-Quartz") - 640g fine sand - 640g mason's sand
Mix these aggregates together. Aggregates not very key -- use whatever sandy/limestoney stuff you got. Mix in GP binder. Ta-daa! Cures 60*F - 100*F. Keep moist / cover with plastic. Set indoors without any further action. Takes a few weeks to be sure it's gonna last.
overal ratios 1:2:2 -- powder aggregate : fine aggregate : coarse aggregate 4:5 -- gp binder : aggregate 2:1.5:.5:1:2:2 -- sil-sol:metakaolin:water:si-flour:fine-sand:mason-sand
Note: Metakaolin is a pozzalon. Any aluminosilicate pozzalon could potentially work. Slag powder ~= volcanic ash ~= 750C calcined kaolin ~= PowerPozz ~= grog from failed bisqueware.
Advice: Aluminosilicate species dictates ratio of silicate solution to pozzolan. Kaolin != metakaolin != mullite != clay from my yard. Wikipedia those terms.
Head's Up: We know this is an incomplete recipe... like, what are the "open" and "set" times? Responds to kneading? Use gloves? Why all the sitting? Is there a secret magnesium crystal ingredient? Blood and bone ash from sacrificial animal? You tell us.