The search for increasingly efficient materials, especially in the building sector, leads to reconsider natural materials such as wood, whose mechanical properties are particularly interesting.
American researchers have managed to make wood as strong as steel. Indeed, wood is a material of the future with many advantages. Inexpensive, easily accessible, very good insulator, it is also provided with a nanometric structure that allows it to be both flexible and resistant.
This is evidenced by a building currently under construction in Norway which will become in 2019, with its 18 floors and 80 meters high, the tallest wooden tower in the world.
The team from the University of Maryland, USA, has improved the properties of chemical and mechanical treatments with a particularly effective recipe.
The researchers first boiled wood in a caustic solution for seven hours to clean its pores and reduce its lignin content by 40%. Then they compressed it for a whole day at a temperature of 100 C°. This treatment has reduced its volume by five, while increasing its resistance to pressure by 11.5.
To test the hardness of the material, the team submitted several samples to ballistic fire. A board of only three millimeters made up of five layers of this densified wood is thus able to stop a metal projectile launched at 30 millimeters per second. According to the researchers, this type of impact is
comparable to that encountered during a collision between cars, which shows that this material would be ideal for vehicle construction.
Kenza, Consultant, Leyton France.
