A report by Eric Hunting:
(for more direct info, see the Geopolymer House Blog)
“Geopolymer is the general name of a growing family of materials offering a low-carbon alternative to traditional cements and concretes. Based on inorganic aluminosilicate chemistry rather than the calcium carbonate chemistry of traditional portland cement, geopolymers get their name from their cross-linked molecular chain structures which parallel those of plastics. In some cases geopolymers are referred to as a class of ceramics. Geopolymers are superior to cements in many ways and have become popular for military applications where their great strength and rapid curing affords very quick repair of critical installations like airstrips. Their second-largest application to date has been in the arts, as the basis of cast stone used for mass-reproduced sculpture and lawn ornaments. Much more recently they have become the focus of alternative architecture with a steadily increasing amount of experimentation and application in large scale 3D printing of resilient structures hinting at the possibilities of future large scale automated construction. Their ‘green’ qualities come chiefly through a much reduced need of energy in their production and the ability to incorporate and repurpose a vast assortment of industrial wastes such as fly-ash, rice hull ash, and hemp chard.
Though modern forms of the material were developed in the late 1970s, the root technology is apparently quite ancient and derives from the chemistry of ‘roman concrete’ and even earlier materials. Some forms, such as the French-developed Isochanvre based on siliconized hemp chard, are said to be directly reverse-engineered from these ancient materials. Much controversy has been caused by theories that geopolymer was used in the construction of ancient Egyptian pyramids and other ancient architecture, ‘stones’ being cast-in-place rather than cut and moved whole. This idea has sometimes become a distraction to geopolymer development–as associations to the ‘mysteries of the pyramids’ that so obsess the New Age culture tend to inspire a negative image in engineering and science circles. Despite this ‘pharaoh’s curse’ of sorts, geopolymer has clearly demonstrated countless practical uses and tremendous commercial potential and so its development continues. It’s chief limitation today has been a simple lack of supply at affordable prices, (a logical consequence of having an initial market in the spendthrift defense industry…) which many ‘grass roots’ alternative architecture researchers seek to overcome by more natural and recycled sources of material.
Authored by Owen Geiger, the Geopolymer House Blog seeks to document the development of open source housing and construction based on this remarkable material. So far the site does not detail any specific building projects but the author has clearly been deeply researching this technology and has so far collected an outstanding base of material on this subject. This site is an excellent resource for those interested in geopolymers, their huge array of applications, and the many kinds of architecture they can potentially be applied to. The author has also participated in the recent $300 house design challenge, which gives us a good impression of where this project is likely to head with its designs.
I’ve long been very interested in geopolymers, both for their green virtues and their potential in applications like marine architecture and foamed fiber-reinforced geopolymer composites. This is very likely to become an increasingly important class of materials in the near future as we search for ways to reduce the environmental impact of the built habitat. A common dichotomy exists in the ‘problem’ of cost-efficient housing. In industrialized nations labor costs and the ‘cost of money’ dominate the costs of quality housing while in the developing world materials, tools, and technology dominate that cost. Quite often solutions to the ‘housing problem’ in one regional context do not apply in others. With geopolymers we see a technology that seems to bridge this dichotomy with the diversity of its application. In the industrial world context we see the potential in geopolymers as the basis of very light and strong precast elements and whole home construction automation based on the use of this material with robotic extrusion. In the developing world, we see its very low energy overhead and ability to repurpose waste materials–particularly those produced by food staples such as rice–as a powerful way to reduce the costs of a high performance building material. There are very few technologies that have such broad potential impact.”