Plastic bricks are made of plastics. That’s what they are. You guessed it! But they come in different forms, shapes and compositions. They can be made entirely of plastics, a mix of plastic fibres, compressed or even simply as plastic bottles.
Plastic bricks can be are being used for housing construction . . . there are several prototype homes. It is an exciting idea. Using them for housing is an effective way for recycled plastic waste to become valuable products.
Suppose 30% of new houses were constructed with plastic bricks. In that case, we could save the planet from several million tons of plastic waste generated annually worldwide.
Table of Contents
“Less than 10% of the estimated seven billion tonnes of plastic waste existing worldwide has been recycled”
Environmental sustainability is a primary driver for using recycled plastic waste for construction.
Countries by estimated mass of mismanaged plastic waste (millions of metric tons) generated in 2010 by populations living within 50 km of the coast
Credit: Jambeck et al., (2015)
Recycling plastic waste could result in more affordable houses.
While many people (including you?) are enthusiastic about plastic bricks’ potential, it is not all roses and sunshine. Plastic bricks can release poisonous gases such as mercury and are inflammable . . . it is valid for repurposed plastic bottle bricks. What about the other types of plastic bricks?
Common types of plastic bricks used for home construction
Plastic sand bricks
Making plastic sand bricks requires heat to melt the plastic waste into a paste. Before heating, sand and other additives may be added.
The sand may be river sand. Others use foundry sand.
Some people add a portion of clay to the mixture. Of the different types of plastic, polyethylene terephthalate (often abbreviated as PET or PETE) is mainly used. Clearwater bottles, for example, are made of PET.
These are then mixed at a high temperature. The resulting paste is compressed into the required brick shapes and dimensions using moulds. The molten plastic acts as a binder like cement in making sandcrete blocks. Plastic sand bricks are different from plastic bricks, composed of mainly recycled plastic.
“The exact proportions of recycled plastic and foundry sand may vary. The mix ratio of sand to plastic (by weight) 70%:30% and 60%:40% has superior compressive strength than fired clay bricks”.
Advantages of plastic sand bricks
1. Plastics absorb water to a very negligible degree. Similarly, plastic sand bricks absorb very little water. Kumar et al.’s (2021) review of studies testing water absorption of plastic sand bricks observed that depending on mix ratios of plastic and sand, absorption rates ranged from 0 to 6.5%. Indeed, soaking the bricks in water did not compromise their compressive strength.
2. With low water absorption, plastic sand bricks are suitable for construction in waterlogged areas. These bricks are resistant to oil and acid. no lengthy period for curing
3. Recycled plastic bricks provide a cheap and better thermal comfort with good insulation properties compared with traditional brick blocks and prefabricated concrete blocks
4. Plastic sand bricks have a high compressive strength
The high compressive strength depends on the mix ratios of plastic and sand. At 5%, 15%, 25% and 35% plastic waste (by weight), the resulting bricks had a compressive strength of 9.86, 10.46, 11 and 10.63 N/mm2, respectively (Mohan et al., 2016).
With a compressive strength of 38.14 MPa, Aneke & Shabangu (2021) found that 70%:30% of foundry sand to scrap plastic waste ratio had the optimal compressive strength. These plastic bricks are twice stronger than clay fired bricks.
5. They are cheaper to produce than clay fired bricks.
Compared with conventional bricks, the energy requirements for making plastic sand bricks are much lower. Plastic melts at about 250 degrees Celcius. After about 10 minutes of melting, the molten paste reaches a viscosity suitable for mixing with the sand. On the other hand, conventional clay bricks are usually fired at 1100 degrees Celcius for 10-40 hours, depending on the volume of bricks and kiln design.
Plastic sand bricks are at least 16.5% cheaper to manufacture than fired clay bricks.
Aneke and Shabangu considered only electricity costs to produce plastic sand bricks and clay fired bricks. This comparative cost-effectiveness will undoubtedly change once other cost elements such as labour are considered. This favours plastic sand bricks since clay bricks require more man-hours.
6. Plastic sand bricks are an effective way of dealing with the plastic waste produced annually and reducing pollution.
See here for Common mistakes people make using Hydraform
Disadvantages of recycled plastic sand bricks
The plastic sand bricks are still largely experimental and not widely used in construction, indicating practical challenges with the product.
1. There are uncertainties about the lifespan of recycled plastic bricks. Plastic degrades over time due to exposure to UV light from the sun through a process known as photodegradation. Degradation will eventually weaken the strength of the bricks and make them brittle.
2. Degradation of plastic could release harmful toxins and microplastics that affect home occupiers’ health or leech into groundwaters. From this standpoint, it can be argued that recycling plastics into bricks pushes forward the plastic waste menace.
3. Depending on the ratio of plastic to sand, these bricks may not be suitable for load-bearing walls.
4. Plastic is inflammable. If such a house should catch fire will release toxic gases harming any inhabitants and into the atmosphere.
- If they are produced as interlocking plastic bricks, the material to be used for the mortar joins isn’t straightforward
Recycled plastic bottles for housing construction
This technique is the cheapest using single-use discarded plastic bottles such as water bottles. The empty PET bottles are used for construction without any modification. So it’s more like repurposing used bottles.
The retrieved bottles are simply filled with sand, earth or mixed inorganic waste. They could also be filled with other non-biodegradable plastics.
A stick can be used to compress the sand/plastics in the bottle.
It is an innovative low-cost solution for construction and dealing with plastic waste in countries with low recycling capabilities.
The filled bottles replace the use of conventional bricks.
To build, the filled bottles can be stacked together using mortar (figure 1).
Credit: Kavaarpuo (2020)
An alternative is that the house’s structure is built using reinforced steel bars and wire mesh. The exact type of steel bars could differ. The bottles are then stacked together in-between the steel frames. The empty plastic bottles are basically used as infill. In other words, they replace the use of conventional bricks. Afterwards, the walls are plastered with mortar to conceal both the bottles and the steel structure. Covering the bottles is aesthetically more attractive. Isn’t it?
Credit: Plastic Bottle Village (2018)
10,000 plastic bottles could build a 100 sq. metre house.
A two-bedroom house requires about 14,000 bottles of uniform size to build
Plastic bricks are also termed Ecobricks. The construction technique, the EcoTec technique, is an effective way of recycling plastic bottles.
Advantages of constructing houses with plastic bottles
- Saves the planet. Yes! It reuses waste bottles that would otherwise be landfilled or disposed of indiscriminately. So they are often termed EcoBricks.
- Using plastic bottles is a low-cost housebuilding solution. Waste bottles are literally for free. Additionally, you use fewer construction materials than a typical housing construction project. They can reduce construction costs by 54%, at least in Bangladesh.
- Easy to use in building with less professional training required
Plastic walls are earthquake resistant since they are lightweight.
Depending on the filler material, they have an impressive compression strength of up to 20 times that of conventional clay bricks.
With steal reinforcements, plastic bottle bricks can construct low-rise multi-family apartments.
Disadvantages of constructing houses with plastic bottles
- The unplastered/unrendered plastic bottle houses are aesthetically weird, isn’t it? And they scream cheap. They are often associated with rural housing.
- The construction process is labour intensive. The bottles must be gathered, filled with sand and stacked together. There’s no opportunity for using prefabricated parts. Unless in a DIY project, if labour cost in your community is expensive, the cost savings for using plastic bottles could actually be negligible.
- Building and planning regulations may not accept it, depending on your jurisdiction.
- The compressive strength, thermal shrinkage, and density of plastic bricks filled with inorganic materials depend on the filling material.
- Repurposed waste plastic bottles may not provide adequate security from intrusion depending on the infill material.
How much does it cost to build a house in Ghana? Find out here
Fused recycled plastic blocks
This technique uses only plastic waste (and other non-recyclable waste). Except for Styrofoam, all different kinds of plastic waste can be used.
First, these plastic waste materials are collected and shredded. The shreds are then fused together using steam. The plastic waste is fused instead of heated into a molten paste. The resulting blocks can be customised to specific densities and have interlocking features. The blocks are dry-stacked instead of with mortar.
ByFusion is one of the first companies to develop the technique of fusing plastic waste to produce blocks called ByBlock.
Credit: ByFusion (2022)
Advantages of fused recycled plastic blocks for housing
- These blocks have interlocking features. No mortar or adhesives are required to build. Simply stack them.
- One need no specialised building skills aside from what is necessary to set out the dimensions on the ground and outline the walls.
- Absolutely no waste is generated in the process of manufacturing the fused blocks. So these blocks are environmentally friend
- Since specialised labour is not required, this translates into cost savings
- They are water-resistant. Of course, these blocks are made of plastic!
Disadvantages of fused recycled plastic blocks for housing
- The fusion of plastic waste into blocks requires proprietary technology. This situation limits accessibility to technology.
- These blocks are not more flammable than timber-frame houses. They are both Type 5 constructions. Many modern single-unit family houses with wood frames and roofs are classified as Type 5 Constructions. This means that such structures are not fire-resistant, with a risk of building collapse in case of a fire. Additionally, plastic releases highly poisonous gases when burned.
- Since ByFusion’s technology is patented, it is unlikely that researchers will examine it to provide peer-reviewed findings
- Making Byblocks have a substantial initial investment cost. The large blocker with the capacity to produce over 90 tons of plastic waste monthly reportedly costs $1.3 million rentable for $280,000 annually.
Key take aways
Plastic means many things. It could be plastic sand bricks, recycled plastic bottles, or fused plastic waste bricks. Other types of plastic bricks, aside from these, depend on their exact constituents. Therefore, people may be talking about different things while referring to plastic bricks.
Similarly, techniques and methodologies for making plastic bricks vary. These affect the qualities of the bricks. And since most are experimental, the comparison of brick quality is not straightforward.
Notwithstanding the composition and manufacturing techniques, plastic bricks are generally superior to fired clay bricks in terms of compressive strength, water absorption, tensile strength and efflorescence. They are also comparatively cheaper to manufacture and build homes with.
What do you think about homes built with plastic? Will you live in a house built with recycled plastic waste?
Research cited in this post
- Aneke, F. I., & Shabangu, C. (2021). Green-efficient masonry bricks produced from scrap plastic waste and foundry sand. Case Studies in Construction Materials, 14, e00515. https://doi.org/10.1016/j.cscm.2021.e00515
- Haque, Md. S. (2019). Sustainable use of plastic brick from waste PET plastic bottle as building block in Rohingya refugee camp: A review. Environmental Science and Pollution Research, 26(36), 36163–36183. https://doi.org/10.1007/s11356-019-06843-y
- Jambeck, J. R., Geyer, R., Wilcox, C., Siegler, T. R., Perryman, M., Andrady, A., Narayan, R., & Law, K. L. (2015). Plastic waste inputs from land into the ocean. Science, 347(6223), 768–771. https://doi.org/10.1126/science.1260352
- Kumar, R., Kumar, M., Kumar, I., & Srivastava, D. (2021). A review on the utilisation of plastic waste materials in bricks manufacturing process. Materials Today: Proceedings.
- Mohan, C. G., Mathew, J., Kurian, J. N., Moolayil, J. T., & Sreekumar, C. (2016). Fabrication of plastic brick manufacturing machine and brick analysis. International Journal for Innovative Research in Science Engineering and Technology
