any geopolymer -flyash-concrete in USA yet?
any geopolymer -flyash-concrete in USA yet?
(OP)
I have recently read several reports from India and Australia regarding their use of geopolymer-flyash concrete . Results indicate that 28 day compressive strength is over 50 MPa( over 7250 psi), and zero portland cement is utilized. Basically , class F flyash + sodium hydroxide plus sodium silcate are used as replacement binders in lieu of portland cement. CO2 credits associated with this is 1 ton of carbon credited per ton of this concrete.
We have 50 yrs accumulation of flyash from our coal fired plants, and viewing this flyash as of equivalent value as portland cement might lead one to think we are now sitting on a gold mine.
Are there any USA applications of this technology ?
We have 50 yrs accumulation of flyash from our coal fired plants, and viewing this flyash as of equivalent value as portland cement might lead one to think we are now sitting on a gold mine.
Are there any USA applications of this technology ?





RE: any geopolymer -flyash-concrete in USA yet?
Any old fly ash in the U.S., even if possibly acceptable to make it usable for any high volume since it obviously is not stored in bins, but on the ground or used to fill large holes or swamp lands. In the U.S., properties are determined by the fuel used and the type of collection methods. Both type C and type F have been available, but the good fly ash is already under long term contract to the cement companies as a raw material or the international admixture companies for use as an admix.
What many people around power plants see is "bottom ash", which is course, contains some heavy metals and needs to be processed.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: any geopolymer -flyash-concrete in USA yet?
I was working on a less ambitious application, still am, as time permits.
I used Class F fly ash from a plant in the four corners area. It worked well. The fly ash does not even need to be particularly clean, although an old deposit would be a lot of work to use. I have read that Class C might not work as well due to interference with the polymerization process from the additional CaO present. I have not tried to use Class C fly ash personally.
RE: any geopolymer -flyash-concrete in USA yet?
a) 2-4 times the compressive strength and up to 10 times the tensile stength of OPC
b) directly bonds to reinforcement filament wires, leading to a true composite material, suitable for many deense related purposes
c) fireproof, strong to 1000 C, stable to 1600 C
d) very short initial curing period, to >10 MPa in 4 hrs ( used as emergency runway cement repair patch )
e) non-leaching of heavy metals for a large family of metals, may be considered as an alternative to vitrification for some metals
f) very low CO2 footprint, may qualify for 1 ton of carbon for each tonof concrete used.
My own limited application is to convert flyah deposits to beneficial use while consuming FGD purge wastewater. Maybe paving bricks or highway barriers as final product.
It has potential to be a "disruptive" technology.
RE: any geopolymer -flyash-concrete in USA yet?
RE: any geopolymer -flyash-concrete in USA yet?
we have class F flyash- 50 yrs accumulation from several plants. More important we have a wastewater stream of 1500 gpm from the fFGD purge. At issue is whether this wastewater can be used with the dry NaOH , as it contains 10,000 ppm chlorides and also boron and selenium, 2 metals tha may leach from geopolymer concrete. Also,the purge has high levels calcium sulphate- perhaps we will need to soften the wastewater and remove the Se with a bioreactor prior to mixing with NaOH , etc.
RE: any geopolymer -flyash-concrete in USA yet?
RE: any geopolymer -flyash-concrete in USA yet?
I forgot to mention- we would be reducing the wastewater flowrate by a factor of 9:1 by first using a falling film evaporator. The resulting wastewater flow would be in the range of 150-200 gpm, with a chloride content up to 90,000 ppm. The concentration of heavy metals to be similarly increased.
Some published papers suggest the Se and B will leach out, so the Se to be first reduced via a bioreactor and the B maybe reduced via electro coagulation.
The slow increase in US adoption of GPC geopolymer concrete ( compared to india, china, Mideast) appears to be due to the massive investment the existing concreet industy has in the status quo. Developing countries have a cleaner sheet to start with, and may have less difficulty lobbying their standards organizations to accept the new technology.
RE: any geopolymer -flyash-concrete in USA yet?
http://www.grancrete.net/