Recycling Plasterboard
by Warren McLaren, Sydney on 05. 7.07
Was reading about a New Zealand company, Winstone Wallboards, who were looking at the resource recovery of their waste plasterboard via compost into a soil conditioning product, and then remembered how an Australian building giant CSR were once recycling clean plasterboard from building sites for use in new production. And it got me to thinking, what is happening with this stuff. Plasterboard, also known variously as gypsum board, drywall or wallboard is basically powered gypsum minerals (calcium sulfate dihydrate) mixed in a water slurry, dried and stuck between two sheet of thick paper (often post-consumer, recycled newsprint.) It is used extensively for interior walls and ceiling. And we mean extensively. Over 80 billion square feet of the stuff per year globally, and roughly 30 billion square feet (2.8 billion square metres) of that manufactured annually in North America. Much of which is subsequently wasted. Depending on the style of house, plasterboard can make up 13% to 20% of new house construction waste. And according to some, “on an average day 40,000 tons of gypsum waste (equivalent to 40,000 cars) is being landfilled around the globe. Every day. 365 days a year.” Gypsum plasterboard is a pretty benign product environmentally (if one looks past the mining extraction and C02 emitted in transporting its heavy weight about the place), particularly with regard to toxins. But it seems this might change when it meets organic waste and rain in some landfill sites. Apparently tests have indicated that hydrogen sulfide gasses can then develop. To the point that landfill bans are being considered in the EU and Canada. But solutions may be at hand.
Gypsum Recycling International have developed a system of plasterboard recycling that they have rolled out across Denmark, Sweden, Norway, The Netherlands, United Kingdom, Ireland and more recently the US. They claim they can capture 94% of the board as gypsum for use as a feedstock for new production, displacing the need for up to 25% extra new raw materials. The remaining 6% waste, the paper substrate, is sent off for use in composting, heat generation and other building materials. But none of it goes to landfill. Their mobile recycling units can be transported to building or demolition sites, and have been developed to cope with contaminates like nails and screws.
Where such cradle to cradle recycling is not available, it is great to see that at least the waste gypsum is put to good use breaking up clay rich soils, via products such as offered by the Envirofert products back in NZ, LimePlus in Australia or investigated in the UK and the US, though there is some concern about additives that might’ve joined the gypsum at the manufacturing stage.
Thought process stimulated by Waste Streams magazine.
I work for a large manufacturer of gypsum wallboard in the US and the author is correct;the paper surrounding our wallboard is 100% post-consumer recycled. The gypsum inside is not added back into the manufacturing process yet however we are one of the two companies that have signed on with Gypsum Recycling International. We make other products that get screwed/attached to walls/floors/ceilings that are concrete type backers. These have very high recycled content (90-100% depending on the product).
Not quite straw-bale and mud but easier to paint. (With low V.O.C. paint of course)
What is the name of this company?
Much of the gypsum board waste occurs at the job site - small cuttings that can't be used, etc.
The builder of a net-zero energy home project in Edmonton, Alberta, Canada simply puts the waste inside of the empty interior wall cavities. The 600 Kilograms of waste per house acts as solar mass, slightly increasing the energy-efficiency of the house. Plus, it is diverted from the landfill for as long as the house stands.
It really is an amazing house. Edmonton gets *really* cold during the winters, so zero-net energy is very difficult to achieve.
http://www.riverdalenetzero.ca/