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      Wheat: Bake it or Build with it?

Prairie farmers might just have a new market for their stockpile of wheat. American researches have found an inventive new use for a staple food that has been a part of our diet and culture for millennia. Wheat starch is being tested as an inexpensive and lightweight aggregate in concrete. Potential uses for this concrete include roofing tile, insulation, flooring, soundproofing and water-resistant backing for shower stalls.

Scientists at the Agricultural Research branch of the USDA-ARS in California led the experiments and eventually perfected the technique. First, a mixture of wheat starch and water is heated, then poured into a mold and allowed to cool into gel form. Next the gel is air-dried until it is transparent and brittle. It is then ground into particles similar to the texture of sand. These particles are soaked in water for several hours then rinsed and drained. The result is a tough rubbery aquagel aggregate that can be mixed with cement and can withstand the force of a cement mixer.

Testing has revealed numerous other benefits to wheat-starch aggregate. Compared with other lightweight aggregates, this one requires little energy or labour to produce. It also produces a superior concrete with a density that tends to remain uniform to considerable depths. Other aggregates made from foams or foaming agents do not perform as well-if they are poured too deep the weight of the mixes can compress the bubbles yielding concrete that is denser at the bottom than the top. Wheat-starch aggregate helps produce predictable, consistent concrete.

Modern improvements have resulted in more durable, waterproof and aesthetic products though it may be more fair to say we're tinkering with an amazing and ancient discovery. The Romans used a lime, water and volcanic ash version to build their aqueducts 500 years before the birth of Christ. The same concrete is in the walls and dome of the Pantheon in Rome (it was rebuilt in 200 AD). This technology survived in Spain and Africa and was likely brought to North America by the Spanish explorers in the early 16th century.

Concrete made its next great leap forward in 1824 in Britain with the invention of Portland cement. This cement made a stronger more durable binder than lime. Portland cement mixed with local stone, gravel and sand became the basis for many "leading edge" technology homes in New York in the late 1800's. Concrete's greatest selling point was it's fireproof nature so important at a time when fire-fighting equipment was minimally effective and homes would often burn to the ground.

Thomas Edison even became an advocate of concrete. He was reportedly appalled by the overcrowded tenements of working class families in the early 20th century. Edison wanted to create larger less expensive housing with the added safety of being fireproof. With the application of his ingenuity a six-room concrete house could be built for $1,200 (not current dollar value!) Few people realize he also set to work on perfecting cement and in 1902 he opened his own highly efficient concrete factory in New Jersey. More importantly he designed interlocking cast-iron molds for casting concrete wall panels. This made transportation and construction relatively simple.

As the needs of architects and homebuilders evolve concrete is sure to keep pace. As for wheat, would you like that in a bagel or in your concrete floor?

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