In the guide below, we discuss the use of post consumer plastic waste in building and construction materials, and applications like concrete/cement, bricks, & paving blocks.
This guide might complement our separate guide on the range of other uses for recycled or re-purposed post consumer plastic waste.
Summary – Plastic Waste Used In Building & Construction, Concrete, Bricks, & Paving Blocks
Plastic Waste/Recycled Plastic vs Virgin Plastic
There might be a range of differences and tradeoffs to consider when using post consumer plastic, and virgin plastic in building and construction
We list those potential differences and tradeoffs in the guide below
Plastic Waste Used In Building & Construction (In General)
It might be accurate to say that at this point in time, the use of virgin plastic in building and construction far outweighs the use of post consumer plastic waste.
Post consumer plastic waste might still be in the testing or research stages, or be used for prototypes and also for very small scale use across many applications in building and construction.
Some regions of the world may also currently use post consumer plastic waste in building and construction more than others.
Plastic Waste Used To Make Building Materials
Many building materials produced with post consumer plastic waste can be plastic composites that are combined with other materials to make the finished product.
Plastic Waste Used In Concrete & Cement
There’s a number of ways different types of plastic and plastic waste has been used in and for concrete and cement.
We list those ways in the guide below, in addition to outlining what some of the potential benefits of this might be.
We also outline what some of the issues or drawbacks using plastic in concrete might be.
Plastic Waste Used In Bricks & Building Blocks
Bricks using plastic waste might currently be sold and used in specific parts of the world, and building blocks might currently be under testing and development
Plastic Waste Used For Paving Blocks
Paving blocks using plastic waste might currently be at the testing and development stage.
Using Virgin Plastic vs Plastic Waste & Recycled Plastic In Building & Construction
Firstly, there’s might be a difference between:
– Using virgin plastic in building and construction
– And, using plastic waste or recycled plastic in building and construction
Virgin plastic has a number of different desirable properties (such as being strong, durable, waterproof, light, and so on) that make it suitable as a building material across a number of different construction related applications.
However, plastic waste or recycled plastic has different properties, such as being weaker, having less integrity, or being a lower quality material.
The reason for this is that when plastic is recycled or processed for re-use (such as being melted down), the bonds between the polymers in the plastic can start to degrade.
To an extent, this issue can be addressed by mixing this plastic with additives, or with virgin plastic
However, recycled plastic waste may not be suitable for some construction applications at all.
Additionally, there’s other differences between post consumer plastic used for building and construction, and virgin plastic
One example of another difference might be cost competitiveness.
In some instances, it may economically feasible, or as profitable, to recover and re-use plastic for construction and building (when compared to other materials).
There are some reports that present a different view to this though.
greenbuildingsolutions.org for example indicates that ‘Recycled plastics can be blended with virgin plastic (plastic that has not been processed before) to reduce cost without sacrificing performance’
Plastic Waste Used In Building & Construction (In General)
It might be accurate to say that at this point in time, post consumer plastic isn’t used on the scale that virgin plastic is used in building and construction materials and applications.
At this stage, post consumer plastic waste used in building and construction might be limited to initiatives, prototypes, and very small scales of plastic waste use.
Developing regions of the world may also use post consumer plastic for some building materials and applications.
From bbc.com:
Existing initiatives [for plastic waste used in construction] are promising, but not yet reproducible on an industrial scale.
Building materials made from recycled plastics are not yet widely used in the construction industry – prototypes have mainly been used for demonstrative installations.
From greenbuildingsolutions.org:
Recycled plastics are used in new building and construction applications every day [with recycled plastic and virgin plastic blends used] to make polymeric timbers for use in everything from picnic tables to fences …
[Plastic from plastic bottles can also be] spun into fiber for the production of carpet …
Plastic Waste Used In Building Materials
Currently, there’s a number of different building materials made with post consumer plastics that are being developed.
Many of these materials can be plastic composites i.e. they are mixed with other materials or waste materials.
From bbc.com:
[Post consumer plastic can be mixed with …] agricultural wastes such as sugarcane bagasse – a by-product of the sugar industry in Brazil – and coffee dregs, to concrete waste and construction debris …
[This can lead to the production of …] bricks, roof tiles, plastic lumber and other useful elements for building.
Plastic Waste Used In Concrete & Cement
There’s a number of ways plastic might be used both for, and in cement and concrete.
Those ways include:
– Using plastic to lower the environmental impact of concrete – specifically carbon emissions
– Using plastic as a partial replacement for coarse aggregate in conventional cement/concrete
– Using plastic fibres in concrete to better hold the concrete mix together, and this may have various effects on the properties or traits of the finished concrete product
– Using plastic as part of an asphalt mix for civil construction surfaces
– Using plastic to partially reinforce concrete instead of steel
– Burning plastic for cement kilns as a fuel
What’s interesting to note is that a range of different types of plastic have been used across these different applications.
However, there may also be some potential drawbacks to using plastic in concrete. Some studies have indicated that it can lead to performance issues in the concrete.
Using Plastic Waste To Reduce Carbon Emissions In Concrete
[Mixing] Plastic waste … with cement [could produce an] eco-friendly concrete with fewer carbon emissions than conventional concrete products … (tpmbuilders.com.au)
Substituting Coarse Aggregate For Plastic Waste
ijstr.org indicates that HDPE plastic has been used as a partial coarse aggregate substitute, with the result being a reduction in concrete weight
Using Plastic Fibres To Better Hold Concrete Mixes Together
concreteconstruction.net indicates that:
[… polypropylene fibers have been used in concrete mixes to hold the mix together]
This slows the settlement of coarse aggregate and thus reduces the rate of bleeding. A slower rate of bleeding means a slower rate of drying and thus less plastic shrinkage cracking. In hardened concrete, polypropylene fibers act as crack arresters.
Concrete For Pathways, Kerbs, & Channels
replas.com.au indicates that there is a sustainable concrete product that is an ‘… alternative to mineral aggregate in [conventional] concrete for pathways, kerbs & channels [and it uses] 100% post-consumer [recovered] soft plastics …’
Reinforcing Concrete With Plastic The Replaced Steel
[In 2018, a technology that] uses recycled polypropylene plastic for reinforcing concrete instead of the traditional steel, [resulted] in reduced CO2 emissions, water usage and fossil fuels (concretepavements.org)
Civil Construction Cementitious Materials & Mixtures
sciencedirect.com indicates that ‘[Plastic waste] can be used as a civil construction material in the form of aggregate in cementitious and asphalt mixtures, filler, insulation [and more]’
Using Plastic For Cement Kilns (For The Production Of Cement & Concrete)
In addition to using plastic in cement mixes, and in other cement and concrete applications, plastic waste can be used for energy to fuel cement kilns
Potential Issues Using Plastic Waste In Cement & Concrete
Several reports from sources like ribaj.com, indicate that there may be issues with synthetic materials like plastic bonding well to the cement mix and sand, and this can weaken the finished concrete material. But, the type of plastic and other factors can impact the strength of the finished concrete product
Another study from iopscience.iop.org indicates that issues may arise when PET plastic aggregate is used as an aggregate for coarse aggregate:
‘The compressive strength, indirect tensile strength and modules of rupture are also found to be decreased with increasing the percentages of PET plastic’
[The mode of failure of the concrete containing waste plastic also changes from brittle failure to more ductile failure]
Plastic Waste Used In Bricks & Building Blocks
Plastic has been used in bricks and building blocks, however, these products are either currently used on a small scale in specific parts of the world (in the case of bricks), or, they are in the development stage (in the case of blocks)
Bricks
From reuters.com:
[In Kenya, bricks made from different kinds of recycled plastic have been developed that are] five to seven times stronger than concrete
[Apart from plastic, the mix includes sand. These materials and heated and compressed into bricks, and then sold]
Building Blocks
From bbc.com:
[Viable building blocks are currently under development, and prospective materials include …] a mix of virgin and recycled plastics … and other local waste-stream materials, such as hemp, sawdust, concrete waste and red mud.
… the properties of the materials [are being adjusted] for the rotomoulding process, a plastics moulding technology that is ideal for making large hollow articles
[Different amounts of recycled plastic can be used in the blocks, and at the moment, 25% recycled plastic content has performed well in testing]
[Blocks usually end up] with a grey or black colour [so] blends of virgin or recycled plastics [overlayed over] the main bulk of the block [can help change the colour]
Plastic Waste Used In Paving Blocks
Paving blocks used for low load bearing areas are different to road paving, which is a plastic road technology.
At this point in time, plastic waste used in paving blocks appears to be at the development and testing stage, and is not widely used.
From ijert.org:
Paver block made using plastic waste, quarry dust, coarse aggregate and ceramic waste have shown [good results, and also show] good heat resistance … compared to … concrete paver block …
A study from from scienedirect.com that involved production and laboratory testing of plastic waste materials in paving blocks revealed:
Waste plastic materials may be used as a binding material for making of paving blocks capable of supporting low load-bearing purposes such as walkways, footpaths, building premises among others in highly moist environments due to their low water absorption capacity
Sources
1. https://www.bbc.com/future/article/20200819-why-plastic-waste-is-an-ideal-building-material
2. https://www.greenbuildingsolutions.org/life-cycle-assessment/recycling-plastics/
3. https://www.sciencedirect.com/science/article/pii/S2214509520300024
4. https://www.ijert.org/reuse-of-plastic-waste-in-paver-blocks
5. https://www.sciencedirect.com/science/article/pii/S2214509519300452
6. https://www.reuters.com/article/us-kenya-environment-recycling-idUSKBN2A211N
7. https://www.concretepavements.org/2018/05/24/queensland-australia-firm-reaches-big-environmental-milestone-in-recycled-plastic-concrete/
8. https://www.replas.com.au/products/polyrok/
9. https://useofcement.cembureau.eu/2018/04/09/cements-solution-to-plastic-waste/
10. https://www.ribaj.com/products/extreme-spec-waste-plastic-in-concrete-university-of-bath-goa-engineering-college
11. R Irmawaty et al 2020 IOP Conf. Ser.: Mater. Sci. Eng. 875 012019. Accessed at https://iopscience.iop.org/article/10.1088/1757-899X/875/1/012019/meta
12. https://www.tpmbuilders.com.au/sustainable-plastic-waste-concrete/
13. https://www.ijstr.org/final-print/aug2019/Use-Of-Plastic-As-A-Partial-Replacement-Of-Coarse-Aggregate-In-Concrete-For-Brick-Classifications.pdf
14. https://www.concreteconstruction.net/how-to/materials/concrete-reinforced-with-polypropylene-fibers_o
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