Plastic waste, a resource for the construction and public works sector

Used plastics find many uses in the construction sector. Many examples of this can be found in large groups and small companies that develop ingenious processes.

Converting  PET packaging waste into insulating foam is a perfect example of plastic waste’s potential as a resource.

Recycling: the construction and public works sector organises its systems Notable examples include the French Soprema company, one of the world leaders in building waterproofing and insulation, which created a new opaque PET tray and bottle recycling system. After multiple tests exploring mechanical and chemical recycling, Soprema’s teams were able to convert opaque PET waste into polyol, a polymer used in the manufacture of insulation foams.

Soprema has stated that it will be able to recycle around 5,000 tonnes of opaque PET in 2019, and potentially double that figure in the following years. In Europe, 70% of the PVC produced is intended for the construction sector. This 100% recyclable polymer is increasingly recycled thanks to VinylPlus, a voluntary commitment made by the European PVC industry which has committed to recycling 900,000 tonnes of it per year until 2025. After being crushed, end-of-life windows, doors, cables and pipes are mechanically converted. The granules thus obtained can then be re-used for the same applications. Another use for the recycled PVC involves incorporating it into sawdust. These plastic/wood composites are mainly intended for manufacturing terrace boards. This material which so perfectly imitates wood has received a warm reception as it is rotproof, does not require any maintenance and is cheaper than exotic wood. In the United States, it is also used as cladding on residential buildings. Finally, studies are being conducted in order to ascertain whether this “new” material can be used in structural components.

A closer look at these new construction materials created from plastic waste

There is no shortage of projects. Some can elicit a smile, while others seem well on the way to being viable. This is the case of the project developed by New Zealander Peter Lewis who came up with the idea of converting plastic waste into bricks. It took him ten years to develop ByFusion, a machine able to chop, wash, rinse and compress any plastic waste and convert it into a 10kg brick in only three minutes. A serious solution for relieving waste drop-off centres. Better yet, his machine is able to change the shape and density of the brick depending on its intended use. These lightweight and solid brick can be stacked without needing to be glued, a little like Lego® bricks. According to its designer, ByFusion’s advantages are many: the process for manufacturing the bricks emits 95% fewer greenhouse gases than that for manufacturing concrete, and all the polymers are compatible. In addition, the plastics are naturally insulating. Peter Lewis was able to secure a subsidy from the New Zealand Ministry of Ecology and has already entered into a partnership with the waste drop-off centre of the city of Dunedin.

On the other side of the planet, in Argentina more specifically, solutions are also being sought. In 2015, a group of young Argentinians created the Fundacion Ecoinclusion to demand a fairer society in a more sustainable world. One of their missions involves making housing accessible to as many people as possible. To achieve this, manufacturing costs in particular, among others, need to be reduced. This team also worked on plastic waste which it was also able to convert into bricks. The only difference is that their process only works with the PET from used bottles, and their bricks require cement to be shaped into a wall. The project was granted the Google Challenge award, evidence of the pertinence of their project. These young people admirably met the challenges of achieving a social and environmental impact. Their bricks were certified by the Secretariat of UN-Habitat and a patent was filed for their machine. Each brick, which requires around twenty bottles, offers the same properties as a clay brick while providing better thermal insulation.

There are many and varied processes for converting plastic waste into bricks. It is an inexhaustible topic of discussion around the world.

The most recent of these remarkable initiatives is Bamboo House, an Indian company initially specialising in building bamboo homes. Its current philosophy relates to considering used plastic bags as a resource and preventing them from being landfilled. Prashant Lingham, the company’s founder, designed a machine able to convert plastic bags into slabs to be used in the construction of small buildings. A two-room house requires 2.5 tonnes of plastic (a few dozen million bags). The roof alone is made up of 5 million bags. The only problem is that the manufacturing process remains expensive and therefore affects construction costs. However, Prashant Lingham hopes to win over many customers convinced of the environmental importance of his project. It should be noted that Bamboo House has already been very successful in creating recycled plastic slabs that have been installed on several sidewalks in the city of Hyderabad. 

Polymers to provide a roof for the underprivileged Every winter, the media jump on the issue. Yet, change is not forthcoming and homeless people die of cold ever year. A young Frenchman has designed a sort of isothermal igloo made from polyurethane foam and aluminium foil. It is not the most luxurious accommodation, but his shelter is able to maintain a temperature of 15 °C inside while the outside temperature drops to 0 °C, and even maintain 20 °C with two people inside the igloo. The concept has already proven its effectiveness. Although it does not solve the housing problem, it serves to deal with emergency situations and save a few dozen lives each year.

It remains an emergency habitat and is therefore precarious, but combining polyurethane foam and aluminium foil made it possible to design an igloo able to withstand severe cold. A low-cost solution that is easy to manufacture.