Kansas student researching how plant waste could become building material

The road to riches for one inventor is paved in agricultural waste.

Lignin — the stuff that makes the walls of plant cells strong — is usually tossed out because it’s so tough and hard to break down. Wilson Smith, a graduate student in civil engineering at Kansas State University in Manhattan, has a plan to use that tough material in construction.

“What it does is it protects the carbohydrates in plants, like the two carbohydrates: cellulose and hemicellulose, it protects them from disease and from pests and it bonds with them,” he said. “It’s just part of its nature to have that sticky quality.”

So, Smith plans to mix it with sand and water to try and develop a substance that is durable and could be used as a rudimentary substitute for cement. The durability improves as the substance cures, Smith said. After 24 hours of curing, it was so strong Smith couldn’t break it with a screwdriver and had to throw it against the ground to get it to smash.

Once it’s cured, the opportunities are at the very least intriguing.

“There’s been some testing, some very preliminary testing of different soil stabilizers in the field,” Smith said. “They took a water truck which had nozzles attached to it, and they sprayed a water/lignin solution onto the soil. They took a roller truck to roll the soil flat again, so it would be flush for an unpaved road. Over a two-year period of time, every six months they went back to the site to do testing over the structural integrity. Lignin performed above average for the two-year span of time.”

What remains to be seen, though, is how water interacts with the lignin. The road test was done in an arid area of Arizona. Though the area gets monsoon rains in the late summer, it’s dry most of the year. Those rains didn’t tremendously degrade the surface, but more testing need to be done, Smith said.

But rather than unpaved roads, the substance may be well-suited for bricks, or perhaps drywall material. But it’ll be some time before what is a laboratory exercise is ready to move into the commercial space.

“Hopefully more people will catch interest in it and people will want to invest more and do more studies and research in it and it will speed up the time,” Smith said. “But I would say it would be few years before you would see any mass-producing of lignin for road stabilization.”