Scientists use recycled glass waste as sand replacement in 3D printing:
Glass is one material that can be 100 per cent recycled with no reduction in quality, yet it is one of the least recycled waste types. Glass is made up of silicon dioxide, or silica, which is a major component of sand, and therefore it offers significant untapped potential to be recycled into other products.
At the same time, due to growing populations, urbanisation and infrastructure development, the world is facing a shortage of sand, with climate scientists calling it one of the greatest sustainability challenges of the 21st century.
For these reasons, the NTU research team is seeking to find ways to recycle glass by 3D printing it into items for everyday use.
One of their innovations published recently in the Journal of Building Engineering, used a specially formulated concrete mix comprising recycled glass, commercial cement products, water, and additives to 3D print a concrete bench. By figuring out the optimal concrete formulation, the NTU research team was able to successfully 3D-print a 40cm tall L-shaped bench (see image) as a proof of concept that their material could be 3D printed into an everyday structural (weight-bearing) product.
In lab compression tests and filament quality (strength) tests, the 3D printed structure showed excellent buildability - the printed concrete does not deform or collapse before the concrete cures -- and extrudability, meaning the special concrete mix is fluid enough to flow through the hoses and print nozzle.
According to the latest data by the National Environment Agency of Singapore, only 13 per cent of the 74,000 tonnes of glass waste generated in the country was recycled in 2021. Without being fully exploited for other purposes, most of the glass waste finds its way into incinerators before being disposed of in a landfill.
While scientists elsewhere have described the use of glass in concrete mixtures, none of them has been able to successfully 3D-print a structure using a glass-based concrete mixture, until now.
[...] As the second most widely used substance after water, concrete relies on sand as a vital ingredient to ensure its durability.
[...] Moreover, as glass is a material that is naturally hydrophobic -- meaning it does not absorb water -- less water is required to create a concrete mix suitable for 3D printing use.
Journal Reference:
Guan Heng Andrew Ting, Tan Kai Noel Quah, Jian Hui Lim, Yi Wei Daniel Tay, Ming Jen Tan. Extrudable region parametrical study of 3D printable concrete using recycled glass concrete. Journal of Building Engineering, 2022; 50: 104091
DOI: 10.1016/j.jobe.2022.104091
(Score: 2, Insightful) by Anonymous Coward on Friday April 29 2022, @02:07PM (3 children)
There's plenty of sand, just look at all the deserts. The problem is a shortage of specific type(s) of sand. From https://www.cnbc.com/2021/03/05/sand-shortage-the-world-is-running-out-of-a-crucial-commodity.html [cnbc.com]
(Score: 2) by PiMuNu on Friday April 29 2022, @02:36PM (2 children)
> The sand that is highly sought after is more angular and can lock together. It is typically sourced and extracted from seabeds, coastlines, quarries and rivers around the world.
Just crush rocks. Job done.
(Score: 0) by Anonymous Coward on Friday April 29 2022, @03:19PM
Much more expensive and intensive in terms of manpower, machinery, and fuel than using sand in the first place. Do you know how fine sand is?
(Score: 0) by Anonymous Coward on Friday April 29 2022, @04:37PM
"sand" the tiny-tiny brick that could...
(Score: 4, Informative) by Snospar on Friday April 29 2022, @06:27PM (9 children)
Who isn't recycling their glass? I've done this my entire life and it's so easy I can't think why people don't do it. It's so ingrained in my routine that I can't comprehend not recycling it - where would I put it... in the landfill bin? Does it need wrapped in paper then? The mind boggles.
At one of my previous houses they did kerbside pick up for glass (and other recycling) but in most locations (UK) I've had to take it either to a recycling centre or more recently drop it off at the supermarket car park - surely that's easy for everyone?
(Score: 0) by Anonymous Coward on Friday April 29 2022, @08:31PM (4 children)
Recycling glass is not cost effective. Sand is cheap. Recycling glass costs money (manpower, machinery, fuel, complication).
(Score: 0) by Anonymous Coward on Friday April 29 2022, @09:22PM (1 child)
In other words, it might be collected with recycling...but depending on the market for recycled-glass that week, it may still wind up in a landfill.
Here (eastern USA), as of last year our recycling only wants clear glass. They told us up front that any colored glass should go into the regular trash (landfill).
(Score: 1, Funny) by Anonymous Coward on Saturday April 30 2022, @10:10PM
That's racist
(Score: 4, Touché) by Michael on Saturday April 30 2022, @12:12AM (1 child)
Sand has to be dug, transported, cleaned, sieved, melted and mixed with limestone and soda ash. All of that takes energy. If the infrastructure exists to supply waste glass to crush into cullet, it is much preferred as a raw material by glass manufacturers.
In the UK 70% or more of the average beer bottle is recycled from cullet. Some european countries manage around 90%.
Hard to see why the glass industry would want cullet at all if it cost more than processing sand and minerals.
I'm curious what your the claim about not being cost effective is based on, if anything. Sure you're not thinking of plastics?
(Score: 0) by Anonymous Coward on Saturday April 30 2022, @03:07AM
So you don't have any idea how much a ton of sand costs.
(Score: 2) by deimtee on Friday April 29 2022, @11:30PM (1 child)
We have two bins here, waste and recycling. The "Recycling" bin takes glass, metal, paper and plastic. I'm pretty sure everything but the metal ends up in landfill with the waste. You might as well call them smelly and non-smelly bins.
No problem is insoluble, but at Ksp = 2.943×10−25 Mercury Sulphide comes close.
(Score: 2) by Michael on Saturday April 30 2022, @12:00AM
Once the metal is taken out, you can separate by density to produce two streams; one to pyrolyse for flammable gas, and one for building aggregate.
Helps landfill volume, not great for co2.
(Score: 2) by Michael on Friday April 29 2022, @11:55PM (1 child)
Singapore apparently.
In the UK about 75% of glass is supposedly recycled. White bottles and jars are the easiest, and typically get made into new glass. Coloured bottles and old windows usually get made into aggregate.
The most efficient way is a separate collection just for glass, like your previous place. Some councils supply a caddy to put the glass into which fits in the top of the wheelie bin. Some don't, such as the area where I worked in a recycling sorting plant. I can't imagine it's very cost effective to have humans and machines separate it out of the stream, but that's indeed what they did.
Probably more to do with increasing the energy density of the remainder, which was destined for incineration to generate electricity, than getting the actual glass.
(Score: 1, Insightful) by Anonymous Coward on Monday May 02 2022, @01:11AM
You mention colored glass is turned into aggregate. Would a simple solution to reduce the amount of colored glass be to simply ban it outright or make using it for trivial things more costly (aka, a tax)? I am sure there are some use cases where colored glass is required (pharmaceuticals, photosensitive chemical storage, etc) but for most it's purely aesthetic. Make all glass transparent...otherwise pay an extra recycle fee upfront.
(Score: 2, Informative) by anubi on Saturday April 30 2022, @06:10AM
My concern is freshly fractured glass has sharp edges, down to the microscopic dust level.
Silicosis. People doing sandblasting don special filter masks to screen the microscopic dusts out.
I also am aware Graphene (form of carbon) is quite dangerous for the same reason.
Search for Graphene sharp edges cell membrane.
https://html.duckduckgo.com/html?q=graphene%20sharp%20edges%20cell%20membrane [duckduckgo.com]
Be careful of dusts that have sharp edges. Doesn't pair well with lungs, stomachs, or intestines.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]