Engineer turning plastic waste into paving bricks

Growing up in Nairobi, Nzambi Matee had seen the challenge the city had in managing plastic waste.

This made her to start thinking hard on how the plastic menace could be solved.

Today, Ms Matee is the founder of Gjenge Makers Limited, a company that manufactures alternative building products using recycled plastic.

“I think plastic is misunderstood. As a packaging material, it is a really good product. But the life after we finish consuming whatever was packaged in that plastic is what we need to understand and structure because plastic has a lot of potential, only if we can structure a healthy life cycle around it,” she says.

The company is making paving bricks, which are mostly used in parking areas or homes.

Before setting up the firm, the holder of a bachelor’s degree in Physics in Material Science and Engineering immersed herself in research work, analysing data on the different components of plastic.

And in 2017, she registered her company. Ironically, this is the same year the government declared it had had enough of the single-use plastic bags and banned them.

“In 2017, all we were doing was research and development and then we figured out how to make one brick using recycled plastic. So in 2018, we had to start thinking big, like if we could make one brick, how would we be able to make, say, 1,000?” explained Ms Matee.

“The next question we needed to answer was on machinery. My team and I checked the internet but we were not able to get what we wanted. We decided to build our own machines. In 2019, we made three machines and assembled the production line. Right now we have capacity to produce 1,000 to 1,500 bricks per day,” she went on.

Plastic, she says, in its molecular structure, is fibrous, which in simpler terms means it is string-like.

To make the pavers, they mix the plastic with an aggregate, in this case sand or ballast. The plastic acts as a binder.

For concrete pavers, the components are cement, water and ballast. But for Gjenge Makers, the function that cement performs is replaced by sand, with the plastic acting as a binder.

“After the pavers are made, we cool them at very high pressures to remove all air pockets. Air pockets are those holes you see on some bricks made out of concrete. These air pockets are very dangerous because they introduce a fault line where the brick can easily break under compression,” said Ms Matee.

Their plastic comes from post-industrial and post-consumer sources.

Post-industrial plastic comes from factories. It is the waste that, after making packaging products, factories cannot recycle anymore.

Post-consumer plastic, she says, is that which is thrown away as garbage by consumers. The garbage ends up in dumpsites, where it is sorted and taken to a recycler.

The recycler then makes pellets, which are small pieces that are used to make other plastic packaging products.

“There is always that waste that cannot be recycled anymore, and that is what we usually take and use in production,” explains Ms Matee.

She added: “You see street children collecting plastic that they sell at a yard. What the yard does is sort the plastic because there are many variations. They then clean it and make pellets. Plastic in this form can then be sold to factories. Our goal is to take the plastic at the bottom of the chain.”

Ms Matee says it took time for Kenyans to embrace  pavers made from plastic as many did not understand the products.

For this reason, the firm was unable to make any sales in  the first year of its operations.

Things have, however, changed. People are more interested in their products and the challenge for the company has shifted from creating demand to supplying.

“The concept of using plastic in the building space is as old as time. The Maasai, for example, to construct manyattas, use mud and straws of grass before plastering the wall. The grass is used to enhance strength. The only difference is that, instead of grass, we are using plastic,” said Ms Matee.

Although Gjenge Makers appears to be offering some sort of solution to the plastic waste menace, Ms Matee says it will take time for the plastic problem to be fully resolved.

“You’ll hardly see scrap metal lying around in Nairobi. That is because recycling of scrap metal is very well defined. If you put a broken chair on the roadside, someone will pick it fast and take it to a recycler, because there is value. That is what we need to do with plastic. We need to structure the recycling system,” she says.