Researchers Find a Safe New Use for Dangerous Asbestos Cement: a 3D Printing Additive

Researchers from the Università di Milano Bicocca, Université de Lill, and Graftonica S.r.l. have come up with a novel way to upcycle dangerous asbestos cement: turning it into a safe additive for 3D printing polylactic acid (PLA), with the potential to print biodegradable objects that won't harm the environment.

"Asbestos cement waste, a hazardous and challenging material to manage, can be deactivated and upcycled as a powder that can be safely used as polymer filler," the researchers explain in the abstract to their paper on the topic. "With a standard twin screw extruder, we produced composite pellets with up to 50 [percent by weight] loading in PLA. They are sufficiently flowable and stable for further application to Fused Granular Fabrication 3D printing, an additive manufacturing method that employs pellets instead of filament."

The mineral asbestos was once regarded as a wonder-material: lightweight, insulating, and fireproof, it found its way into everything from pipe lagging and roof tiles to film and theater — where "white asbestos" was shredded and thrown onto the stage as fake snow. Sadly, all of this turned out to be a terrible idea: when disturbed, asbestos sheds tiny fibers, which lodge into people's lungs causing long-term health problems including mesothelioma.

Owing to asbestos' boom years, and the danger in disturbing it in order to remove it, there's still plenty out there — and it all needs processing to render it safe. This "detoxification" process still leaves you with a large quantity of waste — which is where the team's work comes in. Asbestos cement, a once-common building material that mixed asbestos into cement to strengthen it, lighten it, and protect against fire, is detoxified then used as an additive in PLA. That PLA can then be safely used in existing 3D printers, the researchers claim.

"The filler dispersion is homogeneous, and the mechanical properties of the 3D printed samples are comparable to those of pure PLA up to 20 [percent by weight] loading," the team claims. It's not quite ready for use in home 3D printers, though: the research focused on fused granular fabrication (FGF), which uses easier-to-make pellets of material rather than the long continuous line of filament used in more common fused filament fabrication (FFF) printers.

There's also the potential to add some interesting properties to the finished composite, too. "Depending on the preparation method, the deactivated asbestos can be fully inert or endowed with catalytic properties," the researchers note. "A variant produced in a reducing environment has a strongly hydroxylated surface that can induce PLA chain scission and reorganization from 200°C [392°F], significantly less than the 350°C [662°F] spontaneous degradation of the pristine polymer. This behavior facilitates post-consumer biodegradation while preserving material integrity under standard processing conditions."

The team's work is in press at the journal Discover Materials, with an unedited version available under open-access terms.