Geopolymer

Geopolymer Wikipedia article.

Geopolymer Composites: A Ceramics Alternative to Polymer Matrices About.com article

"...Geopolymer composites have been investigated and developed for a variety of applications. A five-year program funded by the Federal Aviation Association at Rutgers University, in conjunction with France's Geopolymer Institute, looked at developing low-cost, environmentally-friendly, fire resistant matrix materials for use in aircraft composites and cabin interior applications. The goal of the program was to eliminate cabin fire as cause of death in aircraft accidents. Unlike conventional polymer composites, carbon-fiber reinforced geopolymer composites did not ignite, burn, or release any smoke even after extended heat flux. Therefore, they are suitable as aircraft cabin materials for cargo liners, ceiling, floor panels, partitions and sidewalls, stowage bins, and wire insulation.

In France, a fire-resistant geopolymer-encased electronic flight recorder has been patented by S.F.I.M. and jets are also being equipped with a highly advanced fireproof air filter from Sofiltra-Camfil. For Northtrop Aviation, a geopolymer composite tooling prototype (self-heated carbon/SiC/geopolymer composite) was used in the fabrication of a carbon composite designed for a new US Airforce bomber. Formula 1 racing cars have also been built with carbon/geopolymer composites as thermal shields in the exhaust system, replacing titanium...."

Alkaline Cements and Concretes, Properties of Geopolymer cements Technical abstract by Joseph Davidovits

"...The behaviour of geopolymeric cements is similar to that of zeolites and feldspathoids; they immobilize hazardous materials within the geopolymeric matrix, and act as a binder to convert semi-solid wastes into adhesive solids. Their unique properties which include high early strength, low shrinkage, freeze-thaw resistance, sulphate resistance and corrosion resistance, make them ideal for long term containment in surface disposal facilities...."

Hopes build for eco-concrete, 26 January 2008, New Scientist, Rachel Nowak. Melbourne

"...The cluster of beige corrugated-iron sheds and silos don't look like much, but this unassuming factory in a suburb of Melbourne, Australia, represents a potential revolution in greenhouse gas emissions. It's the first commercial enterprise in the world dedicated to transforming waste from power stations and blast furnaces into geopolymer concrete, a particularly promising green concrete.

The factory, owned by the company Zeobond, is due to start operations in February. Unlike with regular concrete the chemical reactions that form this polymer-based alternative don't give off carbon dioxide or require high temperatures, which also lead to CO2 emissions. So it releases just 10 to 20 per cent of the greenhouse gases associated with making the standard stuff.

The first customers for Zeobond's E-Crete will be individuals and local councils, who will use it in small, non-safety-critical projects, such as building patios and walls on motorways that block sound, says company founder Jannie van Deventer, a chemical engineer at the University of Melbourne. If geopolymers like E-Crete prove to be durable, there is no reason why they shouldn't replace regular concrete in a variety of applications, from high-rise buildings to bridges. So says Mark Drechsler of engineering consultancy Parsons Brinckerhoff, who are hoping to use E-Crete to build low-cost housing. "If you replaced just half the new concrete that will be needed over the next 10 years with geopolymers, it would be a reduction of almost a billion tonnes of extra CO2 each year at a time of global demand for reducing emissions," he says.

How bad can concrete be for the environment? The main culprit is the ingredient Portland cement, a fine powder containing calcium, oxygen and silicon, which forms concrete when mixed with water, sand and rocks. To make Portland cement, calcium carbonate, in the form of limestone, and other raw materials such as clay, must be roasted at over 1400 °C. The resulting chemical reaction produces half a tonne of CO2 per tonne of cement. Over a third of a tonne of additional emissions come from burning the fuel to heat the cement kilns and transporting raw materials. Between 5 and 8 per cent of global CO2 emissions are the result of cement production. With demand for concrete set to double in the next decade, the figures will only get more dismal. ..."