Geopolymer FAQ

I keep getting the same questions about geopolymers. So, here are some frequently asked questions:

What is it again?

Clay and other natural earthen materials that are chemically activated to condense into a hard, ceramic material. It is different from conventional cement because it forms a three dimensional covalently bonded lattice work that incorporates the aggregate, where Portland cement is an ionic crystal structure that grows around the aggregate. It is different from conventional ceramics because it requires much lower firing temperatures, but can still withstand metal melting environments.

What do you use it for?

Geopolymers are currently used in a wide variety of applications. Quick setting, high compressive strength concretes, for example. Or as a modifier for adobe/rammed earth/cob to make earthen walls or bricks. Because it does not need to be fired, it has been used as a mineral resin for bonding fibers, such as carbon or glass fiber, to make pressure vessels, sturdy components for F1 race cars and space exploration.

Did you come up with this?

oh, gosh no. Dr. Joseph Davidovits in France has claimed over thirty patents on the process begining 30 years ago. The fundamental patents are now public domain. Davidovits and others are now concerned with spreading the knowledge of this transformative technology. Geopolymer is the public domain name he gave to the process so that it could be discussed without relying upon proprietary information.

How are you involved with this? What is your background?

Early in my college days I realized that the technology available to and used by a society greatly influences the structure of society. If I want to see society change, I had better figure out how technically to make this possible. So, I left school and started somewhere else towards a physics degree. After getting that degree a couple years ago, I began to focus more on researching and analyzing “new” technologies and the historical/sociological origins and impacts that they have.

Many technologies hyped on the news quickly reveal themselves as more of the same. But I have found several ideas that continue to be promising. Geopolymers have grown and grown more interesting to me, seeming always more promising, more possible in a localized permaculture, more useful to communities governing and directing themselves.

Following research with more research, following experiences with experimentation, taking each new step with more interest as the path reveals itself, I have come to this point where definite and achievable goals are apparent. In a short time, much of my years of wondering could condense into a set of real tools for constructing convivial communities.

What is working with GP like?

A thin liquid or very wet clay like material is shaped (poured into moulds, or over fibers, or shaped by hand), wrapped in plastic and allowed to cure. Some recipies require an hour in the oven at 80C (200 F, the lowest setting my oven has), and some cure over more hours outside at ambient temperature.

The change from being moist to rigid is quick, and the polymerization reaction continues for several days (or longer) afterwards as the object becomes increasingly stronger.

The results are not soluble in water and do not decay in acids (vinegar), verifying that a chemical change has taken place. The components of GP are water soluble and react with acids.

What exotic/carcinogenic chemicals do you have to use?

There are no exotic chemicals needed. The most simple mixture consists of powdered kaolin clay, calcinated to achieve chemical activity, which is reacted with lye. Many varieties of silicates and aluminates can also be incorporated, all of which are either naturally occuring or are produced from naturally occuring minerals and simple chemical processes. Fire pit ashes and slags from metal working are examples of these.

But it is expensive, isn’t it?

Depending on the natural geochemistry surrounding an area, it is likely that GP is much cheaper than trying to produce conventional cements, bricks and ceramics. The pure resin is made from ceramics supplies for less than one dollar per pound, which is then mixed with dirt cheap local materials at the rate of 5% to 50%. So, $1 could make over 20 lbs of bricks if you don’t count labor or energy costs (which are less with GP than with other alternatives).

Why haven’t I heard of this?

The fundamental patents have only recently entered the public domain, and many groups using this technology have paid licensing fees on top of R&D. There are academics studying GP, but their papers are very esoteric and incomprehensible to artists and lay folk. There is also some difficulty in crossing a paradigm, as educated people have been taught that only organic molecules are truly polymerised, and that minerals form ionic crystals.

Mainly, the news loves to hype “energy” related technologies. Technology that enables smaller groups of people to live in their own community, with decreased need to import goods or over harvest the land, is just less exciting. Technology has come from meaning “the study of making things” to now refer to only the most complicated products of mechanized production (cell phones and nuclear reactors).