3D-printed sawdust mix makes concrete formwork greener

Image credit: Tharanesh Varadharajan, Zachary Keller, Muhammad Dayyem Khan/Michigan University

A reusable construction product based on waste sawdust that can replace traditional concrete formwork has been developed by researchers in the US.

The University of Michigan’s BioMatters team developed the material, which is said to be fully biodegradable, reusable and recyclable, and is 3D printed to create the required form.

Millions of tonnes of sawdust waste are created each year, according to the Michigan team; generated from the 15bn trees that are cut. Often, this waste is burned on dumped in landfill, where it contributes to environmental pollution.

However, the BioMatters team at the Taubman College of Architecture & Urban Planning, and Digital Architecture Research & Technology (DART) Laboratory have ‘upcycled’ the sawdust to make it the base for their new product solution.

Currently, they are using sawdust created at the Fabrication Laboratory at Taubman.

Muhammad Dayyem Khan, a researcher at the DART laboratory, said: “We have made a recyclable, all-natural biomaterial, which is made out of sawdust.

“Other sawdust-based solutions are using other petroleum-based polymers – we use biopolymers, which are completely decomposable. And the biggest thing is, it’s very easy to recycle and reuse.”

Led by DART director Mania Aghaei Meibodi, along with researchers Tharanesh Varadharajan, Zachary Keller and Khan, the team has proposed a novel method.

Their approach couples robotic 3D printing of the wood-based material, with incremental set-on-demand concrete casting, to create zero-waste free-form concrete structures.

The 3D-printed wood formwork shapes the concrete during casting, and the concrete stabilizes the wood to prevent deformation.

Once the concrete cures, the formwork is removed and fully recycled by grinding and rehydrating the material with water, resulting in a nearly zero-waste formwork solution.

The impact isn’t just beneficial to the construction industry’s environmental performance, either, say the researchers.

Khan added: “When the sawdust decomposes, it is producing fatty acids, lignin, which causes toxicity in water. And once it starts contaminating water, it has its effects on smaller wildlife, microbes and a broad range of organisms. And with sawdust being extremely flammable, its potential contribution to wildfires is very high.”

The BioMatters team’s solution directly addresses the “significant” waste and pollution contributions of the concrete industry, where formwork constitutes 40% of concrete construction expenses. Traditionally made from wood and discarded once deformed, formwork adds to the negative environmental impact of concrete construction.

“The amount of sawdust that is being produced out there – it is a huge chunk of material that is just being dumped or burned,” Khan said. “So rather than burning it up and generating more CO2 emissions, it is so much better that we make it into a material that is actually capable of being used again and again.”

Image credit: Tharanesh Varadharajan, Zachary Keller, Muhammad Dayyem Khan/Michigan University

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