A team of researchers based in Norway and Japan might soon have you walking on desert sand, no matter how far from the dunes you live. This group of engineers has developed a method to transform it into a new construction material that's perfect for pavements – and it can help reduce the need to destructively extract sand from rivers.
It's estimated that about 19 million square miles (30.5 million sq km) of planet Earth is covered by deserts. That's a lot of sand – useless sand, I might add. Meanwhile, sand that's used for concrete and mortar in construction is collected from riverbeds and riverbanks, as well as from crushing quarry stones, and digging up seafloors and pits underground. All of these sources erode or deplete environmental resources.
As such, figuring out a way to make use of desert sand could help offset the damage done to some degree. To that end, researchers from the Norwegian University of Science and Technology (NTNU) and the University of Tokyo have come up with what they're calling Botanical Sand Concrete (BSC), or Sandcrete.
"The challenge is that desert sand is so fine-grained that it is not suitable as a fastener in concrete. In other words, the concrete will not be hard enough to be used in construction projects,” said Ren Wei, a postdoctoral fellow at NTNU who authored the paper on Sandcrete that appeared in the Journal of Building Engineering last November.
After testing a range of types of desert sand and different ways to mix it, the team figured out a recipe combining equal parts of desert sand with powdered wood at a high temperature of 356 °F (180 °C) and high pressure, using a double-plate hot-pressing machine to create blocks.
Instead of a chemical reaction with cement, Sandcrete relies on the lignin (organic polymers) found naturally in wood. Under heat and pressure, the lignin becomes soft and acts like a natural glue that binds the sand particles together. The natural alkalinity of the sand also helps this adhesive bond more effectively, resulting in a block strong enough to be used for pavement bricks, as prescribed by Japanese Industrial Standards.
Despite my opening for this story, the researchers note that Sandcrete will make the most sense when used in arid regions close to deserts, where the sand can be sourced nearby, so it doesn't incur high environmental costs of transporting it over long distances.
“The production process is relatively simple, so in principle the material can be made in many places. But we need to test more, including how it can withstand cold, before it can be used in Norway,” said Wei. The team is also looking into whether agricultural waste can be used in place of wood scraps, further reducing Sandcrete's environmental impact.
Source: Norwegian SciTech News / NTNU
