natural materials

Modern civilization is pretty much made of concrete. People use more concrete than any other substance apart from water. But concrete is made from cement, and cement is the source of 10% of all carbon dioxide emissions worldwide.

Researchers at the University of Washington and Microsoft have developed a new kind of concrete made by mixing dried, powdered seaweed with cement. By fortifying cement with seaweed, the global warming potential of the concrete is reduced by 21% without weakening it.

This novel recipe for concrete was developed using machine learning models, arriving upon it in a fraction of the time it would have taken by traditional experimentation.

Producing cement leads to carbon emissions from the fossil fuels used to heat raw materials and from a chemical reaction called calcination that occurs during the production process. Seaweed is a carbon sink that pulls carbon dioxide out of the air and stores it while it grows. By replacing some of cement in concrete, the resultant product has a much smaller carbon footprint.

Machine learning was used to predict the ideal mixture of cement and seaweed to yield concrete with a reduced carbon footprint that still passed mechanical strength tests. Finding the right mixture would have taken 5 years ordinarily, but the machine learning process took only 28 days.

The researchers plan to generalize their work to different kinds of algae and even to food waste or other natural materials in order to create local, sustainable cement alternatives around the world.

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Seaweed-infused cement could cut concrete’s carbon footprint

Photo, posted June 29, 2009, courtesy of Peter Castleton via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wild bees in Argentina have recently been found to be constructing nests entirely made of flimsy plastic material left on farms and scientists don’t know why.

In 2017 and 2018, researchers at Argentina’s National Agricultural Technology Institute built wooden, artificial nests for wild bees. These bee species burrow into nests to individually lay larvae rather than having a large hive with queens and workers. The artificial nests provide hollow openings that bees generally fill with cut leaves, twigs, and mud.

Sixty-three wooden nests were constructed and three were found lined entirely with plastic. The bees carefully cut bits of plastic in the shape and size of fingernails and arranged them in an overlapping pattern in their nests. The plastic seems to have come from plastic bags or films, which have a similar texture to the leaves bees ordinarily use to line their nests. And, in fact, leaves were readily available to the bees making use of plastic.

This is the first time that bees have been seen making nests entirely out of plastic, but for years scientists have known bees were incorporating plastic into their building materials. Research is needed to determine the potential impact plastic might have on bees, but the nest building shows that bees are highly adaptive to changing environments.

Plastic often forms a threat to wildlife in the form of microplastics that can be consumed. But there is no evidence that bees are consuming plastic. Some researchers have speculated that the plastic in bees’ nests may form a barrier against common nest issues like mold and parasites.

At this point, it is not clear whether it is a good thing or a bad thing that some bees are choosing plastic over natural materials, but it is certainly interesting.

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Wild bees are building their homes from plastic—and scientists aren’t sure why

Photo, posted December 12, 2014, courtesy of Judy Gallagher via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Seaweed and concrete

Modern civilization is pretty much made of concrete. People use more concrete than any other substance apart from water. But concrete is made from cement, and cement is the source of 10% of all carbon dioxide emissions worldwide.

Web Links

Bees And Plastic

Wild bees in Argentina have recently been found to be constructing nests entirely made of flimsy plastic material left on farms and scientists don’t know why.

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