by Wilma Den Hartigh

Two birds, one stone

Finding sustainable solutions to our landfills

Polystyrene has recently become a marketable product which will aid in the construction of sustainable low cost houses
polystyrene.jpg

Recycled Expanded Polystyrene (EPS) is the latest solution to two of South Africa's biggest challenges – the backlog to build sustainable, low cost houses and the need to find ways to prevent the country's landfill sites from reaching their fill capacity.

The new project is proving that used polystyrene doesn't have to end up in the landfill at all – every piece can be used to build environment-friendly houses.

Adri Spangenberg, director of the Polystyrene Packaging Council (PSPC) says that the beauty of the concept is that there is no shortage of EPS in South Africa, and it is free.

The trays used to package meat in supermarkets, cups, packaging material for appliances and fast food containers are just some of the polystyrene products that can be used as building material once it has been discarded.

"This is a new way of looking at building materials," Spangenberg says.

South Africa's own solution

She says that this is the first time the idea to use recycled EPS in construction is being commercialised.

"Before, only entrepreneurs played around with the idea in their backyards," she says.

The project was jointly established by the PSPC and Tower Technologies, a local company that specialises in developing innovative materials for the South African building industry.

Finding creative ways to recycle more of this particular type of polystyrene is important for South Africa.

She says research shows that although polystyrene isn't the main culprit for full landfills (it makes up less than 1% of landfill sites), the product consists of 96% air and takes up a lot of unnecessary space.

Building without bricks

Once the polystyrene is collected, it is passed through a hammer mill to crush the material into small granules before being mixed with cement. This blend is what is used as a building material.

The EPS-cement mixture can be used to make panels or bricks, but for this project panels were made by pouring the mixture into steel frame moulds. The panels are then attached to each other to form the shell of the house.

"The beauty of what we are doing is that it is a national solution to recycling waste," she says.

And it isn't just something that big construction companies can do – all South Africans can use the new technology.

"People in every town, even in the remotest part of South Africa, can buy a hammer mill and manufacture their own building material using polystyrene, whether they want to build a house, spaza shop, or a small flat," she says.

The council and Tower Technologies are still finalising the formula of quantities of cement and EPS regrind, but once testing is complete, they will make the recipe available to the building industry.

Building a pilot house

The first series of EPS-cement demonstration homes have already been built on the premises of discount retailer Makro in Pretoria, Gauteng.

The size of the standard two-bedroom house being built is 26 m2, and it weighs 1.6 tons. It contains 5% EPS regrind (which equates to 75kg), which is thoroughly mixed with concrete to form walls that are almost indestructible.

The polystyrene-based material offers energy saving benefits, good insulation properties and it is lightweight.

"Being lightweight means that anyone can build their own house and it will be durable," says Spangenberg.

It is a much cheaper alternative to normal brick buildings as less cement is used during construction.

If this material becomes more widely used, more people in South Africa can have access to decent housing.

A new market for polystyrene

Thanks to the project, used polystyrene is becoming more valuable in South Africa.

Spangenberg says that one of the biggest challenges has been to keep South Africa's recyclable material in the country. Until recently the council has been struggling to develop markets for used polystyrene.

"One of the biggest headaches we faced when talking to recycling companies and converters was the need to wash and dry the contaminated polystyrene typically used for take-away hamburger clamshells, disposable coffee cups or food trays," she explains.

The challenge in South Africa is that there is a market for white EPS for use in products such as seedling trays; cornices; picture frames; skirtings; coat hangers; and outdoor furniture.

However, coloured polystyrene trays used to package meat or fruit and vegetables have to be scraped clean first to remove leftover food before they can pass through converting machines.

To add to the problem, the high cost of electricity and water in South Africa did not make it financially viable for smaller recycling plants to invest in infrastructure that would mechanise this process.

"This meant that much of the used polystyrene was either sent to landfills or exported to countries such as China and India for recycling," Spangenberg explains.

Members of the building industry have already indicated their intention to use the novel product.

"There is a readily available stream of used EPS in our country and we are able to provide more than enough material for the pilot phase of this initiative."




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