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Recycling concrete with added wood waste

Researchers at the University of Tokyo have developed a new procedure for recycling concrete with the addition of discarded wood, which results in a new building material with superior bending strength to the original material.

Concrete is the most common building material, but because of the large quantity of CO2 emissions it generates during production, it has come under scrutiny. Up till now, concrete recycling consisted of crushing chunks of concrete, adding them as aggregate in the new concrete. However, most CO2 emissions are generated in the production of cement, concrete’s other component.

In order to make a more eco-friendly recycled concrete, the Tokyo researchers used lignin instead of cement. Lignin is the substance that gives wood its rigidity. The lignin, derived from waste wood, functions as an adhesive when mixed with waste concrete powder. This mixture is heated and pressed.

In the right ratio, the ingredients provide a material with superior bending strength than the original material. The method could also be extended to include lignin from other waste plant matter.

Photo: University of Tokyo