'Trash has value': Kenyan inventor turns plastic into bricks

"Plasticstill has value," said Nzambi Matee of the mountains of discarded oil drums, laundry buckets, yoghurt tubs and other trash being shreddedintocolourful flakes at her Nairobi factory.

"I believe thatplasticis one of the misunderstood materials."

The 30-year-oldKenyanengineer andinventorwould know: her start-up recycles tonnes ofplasticdestined for landfillintoeco-friendlybricksthat are stronger, cheaper and lighter than concrete.

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A creation of her own design, these sustainable paving blocks already line roads, driveways and sidewalks in Nairobi, but could soon also serve as an alternative building material for low-cost housing.

Every day her enterprise, Gjenge Makers, churns out 1,500bricksmade from industrial and householdplasticthat otherwise would be dumped in the city's overflowing garbage heaps.

The young entrepreneur quit a job in oil and gas -- the very industry that makesplasticfrom fossil fuels -- to explore recycling after being shocked at how little trash was being reused.

"In Nairobi we generate about 500 metric tonnes ofplasticwaste every single day, and only a fraction of that is recycled," said Matee,whobounds with energy around the factory floor in denim overalls and trainers.

"And that made me think -- what happens to thisplastic?"

Stronger, lighter, cheaper

Most winds up in landfill, rivers and oceans, and less than 10 percent is recycled.

In Nairobi, one of Africa's fastest-growing capitals, Matee found an endless supply of raw material to work with, scouring the city's tips and industrial zones for unwantedplastic.

It took several years to perfect a prototype -- the machinery required was custom built and sourced from spare industrial parts -- but by 2019 production was steadily underway.

The shreddedplasticis mixed with sand and subjected to extreme heat, producing a sludge that is mouldedintodifferent sized blocks.

The end result is a paver that is anywhere between two and seven times stronger than concrete, half the weight, and as much as 15 percent cheaper, says Matee.

It is also more durable.

Plasticis fibrous in nature, and the unique production process prevents air pockets from forming within thebricks. This results in greater compression strength than conventional paving stones that crack under heavy force or prolonged weather exposure.

"Because of that, it doesn't break," said Matee, clapping two of theplasticbrickstogether sharply.

In 2021, they recycled 50 tonnes ofplasticbut Matee hopes to double that amount this year as production expands.

Big plans

There are limitations.

Of the seven major types ofplastic, only four can be recycledintobricks.

PETplastic-- the kind used inplasticbottles and a major scourge on the environment -- is not yet compatible, but they hope to change that.

"There is more that can be done, there is more that needs to be done. We are just a single drop in the ocean... small, small drops will make a big effect," Matee said.

They are trying to breakintothe affordable housing market by designing a block that can replace or complementbricks, mortar and other standard building materials.

A prototype is in the works, with plans to build a model home by the end of the year.

"We want to be the leaders in alternative building products. Our first area of attack isplastic," Matee said.

Her trailblazing work has attracted accolades, and earned another boost earlier this year after she designed a custom gavel for a major UN environment summit where theplastictrash crisis topped the agenda.

Gjenge Makers has also created over 100 direct and indirect jobs through recyclingplastic–- helping both livelihoods and the environment in a way Matee says wasn't possible working with fossil fuels.

"Let's just say I sleep better," she said with a grin.