Lego Blocks from Straw
Ethanol Producer magazine, California produces 1.35 million tons of rice straw annually from the 600,000 acres (240,000 ha) in rice production, and only 3%–4% of that straw is used commercially.
Stak Blocks are 12" x 12" x 24" (305 x 305 x 610 mm) and weigh 30 pounds (14 kg), with a density of 15 lbs/ft3 (240 kg/m3)—about twice that of typical straw bales. The straw fibers are held together with a polyurethane binder (MDI), used at a concentration of about 2% by weight, according to company president Jay Ruskey. The blocks have a high enough density to create load-bearing walls with simple stacking. (With strawbale construction, load-bearing applications require special measures to prevent cracking of plaster as bales compress over time.) Stak Blocks interlock with molded bumps and dimples (think Lego), leaving a channel that is used for a threaded rod to secure the top plate to the foundation. The cavities could also be filled with re-bar and concrete to create a sort of insulated concrete form, though the diameter of the concrete columns would be fairly small.
Published December 1, 2009
Wilson, A. (2009, December 1). Lego Blocks from Straw. Retrieved from https://www.buildinggreen.com/product-review/lego-blocks-straw