Kenya: This factory makes bricks “stronger than cement” from plastic waste

“Plastic still has value”, says Nzambi Matee, showing heaps of oil cans, bowls, yogurt pots and other waste being ground into small colored flakes at his factory in Nairobi, Kenya. According to her, “plastic is a misunderstood material.” This 30-year-old Kenyan engineer and inventor knows what she’s talking about: her start-up recycles tons of plastic, destined to clog the capital’s landfills, into eco-friendly bricks used in construction. Focus on this promising innovation.

The durable stones she has made herself are already laying some sidewalks, alleys and streets in Nairobi and could soon also serve as an alternative material for building cheap houses. These bricks of a new kind are not only ecological, but also stronger, lighter and cheaper than cement.

Nzambi Matee’s company, Gjenge Makers, produces 1,500 bricks of household or industrial plastic every day. The young engineer left a job in the oil sector – an industry that makes plastic from fossil fuels – to recycle after being shocked by the low amount of recycled waste. “In Nairobi, we generate about 500 tons of plastic waste every day, and only a fraction of that is recycled”remembers the entrepreneur in jeans and sneakers, as he enthusiastically browses her factory. “I wondered: what happens to this plastic?”

Bricks 2 to 7 times stronger than cement

In Kenya and elsewhere, most end their lives in landfills, if not rivers or oceans, with only 10% being recycled. In Nairobi, one of Africa’s most dynamic capitals, the young woman finds more resources than she needs by exploring the city’s industrial zones. It took him several years to perfect a prototype – the necessary machines were custom designed – but in 2019 production could finally start.

The shredded plastic is mixed with sand and subjected to extreme temperatures, turning it into a viscous and malleable material that is formed into bricks of all sizes. The end product: a paver that is two to seven times stronger than cement, but twice as light and even 15% cheaper, Matee says.

The plastic is fibrous in nature and the factory’s unique manufacturing process helps prevent air bubbles. This provides greater strength compared to conventional bricks, which can crack under too much pressure or under the influence of time. “It won’t break”says Nzambi Matee, tapping two stones together.

In 2021 the company recycled 50 tons of plastic, but this year it aims to double that number.

“We are just a drop in the ocean”

The project is not without limitations. Of the seven main types of plastics, only four can be recycled into bricks. PET – mainly used for bottles, one of the major environmental scourges – is currently incompatible, but the company hopes to find a solution. “More can be done, more must be done. We are just a drop in the ocean”she adds.

Gjenge Makers wants to enter the low-cost home market by designing pavers that can replace bricks, cement and other traditional materials. A prototype is under study, with the aim of realizing a model home by the end of the year. “We want to be a leader in alternative building materials. Plastic is our first approach”explains Matee.

His innovative work has won him praise, especially at a recent UN summit in Nairobi, which was mainly devoted to the plastic crisis. Gjenge Makers has also created over 100 direct and indirect jobs. A pride for Nzambi Matee, who has been able to help families as well as the environment, an impossible combination in his previous work. “Let’s Say I Sleep Better”she smiles.


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