A self-healing system for concrete developed in Europe was inspired by a Dutch researcher’s trip to Yellowstone National Park in Wyoming. As concrete ages, water seeps into cracks, which widen as the water freezes and thaws. In the new approach, specific organic mineral precursor compounds plus spore-forming alkaliphilic bacteria are incorporated into concrete during the manufacturing process. They produce calcite particles up to 100-μm in size that are shown to seal micro- to even larger-sized cracks. Erik Schlangen, a professor at Delft Technical University in The Netherlands said he got the idea after seeing deposits of calcite near geysers at Yellowstone. The improvement in crack resistance is said to more than compensate for a 10 percent loss in compressive strength due to incorporation of the bacteria, says Schlangen. The approach will also reduce the amount of raw materials used in concrete.
At IMTS last week, Stratasys introduced two new multi-materials PolyJet 3D printers, plus a new UV-resistant material for its FDM production 3D printers. They can be used in making jigs and fixtures, as well as prototypes and small runs of production parts.
Plastic bags can become useful as either raw materials for plastics or feedstock for fuel. It's when they're not recycled that they become a major problem. That's what California's bag ban will prevent.
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