According to the UN Environment Program, plastic waste reduces the ability of ecosystems to adapt to climate change.
Fortunately, recycled plastic building material provides a sustainable solution to this problem. But, what exactly is recycled plastic building material made from?
Recycled plastic building material is made from post-consumer and post-industrial plastic waste. The plastic waste is collected, sorted, and processed to create new, sustainable building materials. Thus, it’s an eco-friendly way to deal with the plastic menace that pollutes our oceans.
In the rest of this article, I’ll discuss the common plastics used in recycled plastic building materials.
I’ll also discuss the process of making recycled plastic building material.
So, let’s dive into the details!
The following are the plastics used to make recycled plastic building materials:
PVC is the third-most widely produced synthetic plastic polymer. About 40 million tons of PVC are manufactured annually. Therefore, plenty of this plastic material can be recycled for construction purposes.
PVC is ideal for making recycled plastic building material because it’s a high-strength thermoplastic. In addition, it’s resistant to most acids and alkalis and is highly durable.
Since PVC is insoluble in water, it’s used to make waterproof building components such as roofing sheets, water tanks, and pipes.
Polyethylene is the most produced plastic polymer globally. It’s the most consumed plastic in packaging – the most common type of plastic waste.
PE is used to make recycled plastic building material because it’s a durable and cost-effective thermoplastic.
In addition, it has excellent chemical resistance, making it an ideal choice for protective barriers in buildings.
Moreover, its lightweight nature makes it preferred over other materials for construction purposes. Besides insulation, PE makes furniture and windows and strengthens concrete.
PP is the world’s second-most widely produced plastic after polyethylene.
Like PVC, which is perhaps more commonly used to make window frames, it’s a high-strength thermoplastic material with excellent chemical resistance. It’s also easy to melt and extrude into various shapes for construction purposes.
PP is used to manufacture recycled plastic building materials such as cabinets, window frames, door frames, and flooring components. It’s also used to waterproof buildings and make insulation boards.
Due to its durability, HDPE is often chosen over other plastics for demanding applications.
Recycled plastic building material manufacturing plants prefer HDPE due to its strong surface durability.
HDPE is highly resistant to scratches and impacts, some common problems with plastic building materials. It’s used to make recycled plastic building materials such as drainage pipes, conduits, protective barriers, and insulation boards.
The high melting point means PS suits external applications such as cladding, siding, and fencing. Moreover, its flame-retardant nature makes it an ideal choice for electrical insulation.
PS is also used to make recycled plastic building materials such as artificial wood and flooring panels.
The recycling of plastic to make building materials involves the following processes:
This is the first step in the recycling of plastic into building materials. Companies and organizations that collect and recycle plastic waste have collection centers for this purpose.
Alternatively, local authorities and waste management companies collect the plastics and send them to the recycling plants.
Collection centers categorize and repackage plastic waste into different types, such as polyethylene, PVC, PP, and HDPE.
The plastics are taken to a Material Recovery Facility (MRF) for sorting. Sorting involves separating plastics and other materials not meant for recycling.
The following are the methods used to sort the materials for further processing:
- Manual picking: It involves sorting through the material by hand. Non-recyclables, larger particles, and contaminants are removed by hand.
- Trommels: These are drums with holes that rotate constantly, separating finer particles from recyclables.
- OCC screening: It separates old corrugated cardboard (OCC) from recyclables.
- Magnet separator: It removes metals as the materials travel over a conveyor belt.
- Optic sorting machine: It separates the different types of plastics using near-infrared (NIR) measurements.
- Washing: It helps remove adhesives, labels, food particles, and other contaminants attached to the plastics. Friction washers are the most common because they have low operating costs and are highly effective. Failure to wash the plastics can affect the quality of the recyclate.
This is an essential process that involves grinding the plastics into smaller flakes.
After sorting and washing, the plastics are transferred to shredding machines for grinding. The common machines used in this process include:
- Hammer mills: They have a rotary drum for pulverizing the plastics using swiveling hammers.
- Shear shredders: They use rotary cutters to cut the plastic into small flakes.
The shredded plastics are then transferred to a drying machine that helps remove moisture content from the flakes before they’re melted.
This is the final step in the recycling process. It involves melting the plastic flakes into pellets ready for extrusion.
The pellets are heated until they reach a molten state and then transferred to the extrusion machines.
The extrusion process produces recycled plastic building materials with different shapes. Such materials include piping systems, decking panels, siding boards, window frames, roofing tiles, door frames, plastic lumber, and insulation boards.
It’s worth noting that other materials are mixed with molten plastic during the extrusion process to enhance its stability and durability. Depending on the construction material being produced, materials such as wood, fly ash, cement, and sand may be added.
Mixing recycled plastic with other materials is an excellent fortification method. For instance, a study by MIT students states that mixing concrete with recycled plastic makes it 20 times stronger than conventional concrete.
Finally, the extruded materials are cooled and tested for quality before being packaged and sold.
Transforming discarded plastics into recycled plastic building materials is a good way to reduce the amount of plastic waste that ends up in landfills and oceans.
Recycling these materials creates a circular economy that helps reduce our carbon footprint and keeps materials cycling within the economy instead of being discarded.
As we continue to explore innovative ways to repurpose plastic waste, recycled plastic building materials will undoubtedly play a significant role in shaping a more sustainable future.