Hope Mwanake understands the plastic pollution crisis facing Kenya better than most.

An environmental scientist who ran a waste collection service in Kenya's central town of Gilgil, she witnessed first-hand the mountains of plastic buckets, bottles and jerrycans discarded by residents, hotels, shops and schools.

"We were just dumping all the plastic in the landfill. It didn't make sense. We knew there had to be a better way," said Mwanake, 30, at her factory on the outskirts of Gilgil, 120km (75 miles) north of the capital Nairobi.

"We wanted to do something with all this plastic waste, and after a lot of brainstorming, research and experimenting, we came up with a value-added product with market demand that would also help to reduce all this plastic in the environment."

Along with business partner and fellow environmental scientist Kevin Mureithi, Mwanake founded "Eco Blocks and Tiles" in 2016. It is the first company in Kenya to manufacture roof tiles and other construction materials from plastic and glass waste.

The tiles are more durable, lighter, and easier to transport and install than concrete or clay tiles. They are also safer for rainwater collection but are available at a similar cost.

Through word of mouth, promotions in hardware stores, and social media posts, the startup has attracted dozens of homeowners and small businesses this past year.

The company has also gained support from the Kenyan government, which is promoting the use of sustainable greener materials as part of efforts to reduce carbon emissions generated from the east African nation's construction industry.

"With the growing population, expanding urban fabric, commitment to provide affordable housing in Kenya and net-zero carbon buildings by 2050, such products have a potential market," said Kenya's National Construction Authority (NCA).

Pollution is also a concern, so repurposing plastic to build is a "win-win", the NCA added in a statement.

Plastic porridge

A million plastic drinks bottles are bought every minute globally, says the United Nations.

Nearly a third of plastic packaging escapes waste collection systems, and at least eight million tonnes of plastic leak into the oceans each year, smothering reefs and threatening marine life.

Plastic also enters water supplies and the food chain, where it could harm people in the long term, according to the UN.

A global fightback is gearing up - Kenya has banned plastic bags, and other countries are targeting straws or Styrofoam - yet environmentalists say much more change is needed.

With Kenya producing more than three million tonnes of waste per year - of which only eight percent is recycled - scientists-turned-entrepreneurs Mwanake and Mureithi felt something had to be done.

"We examined the properties of plastic and glass, and then we literally cooked empty shampoo and vegetable bottles in a big drum and mixed the molten polymer with sand crushed from glass waste," said Mwanake.

"It looked like a strange porridge, but once placed in moulds and cooled, we found we had a very strong and durable product."

Since the pair set up the company, they have tapped crowdfunding and attracted grants from organisations such as United Kingdom packaging firm Mondi and Netherlands-based VIA Water.

Commercial production of the ecotiles began in 2018.

Each tile is priced at 850 Kenyan shillings ($8.50) - equivalent to the price of concrete or clay tiles.

An average three-bed house requires 1,000 to 2,000 tiles.

The company employs four permanent staff and supports scores of community garbage collectors by purchasing their raw material - plastic and glass waste chucked by Gilgil's residents.

So far, they have turned more than 56 tonnes of plastic waste into 75,000 tiles for 30 homes and businesses.

Saving forests, too

Coffee shop owner Julia Tatton didn't hesitate when she saw the plastic roof tiles on display outside her neighbour's store.

"These tiles are going to last forever and are going to outlive me for sure," she said. "They actually work out cheaper as they are lighter than clay tiles, so you actually save money on the wooden support required to hold them in place."

Customers save up to 40 percent on wood when using ecotiles, said Mureithi, noting that this to the benefit of their wallets and the forests.

The ecotiles are also helping Kenya's booming construction industry cut its carbon emissions by providing more green and sustainable alternatives to concrete tiles.

Cement, a key ingredient of concrete, releases five to eight percent of total global greenhouse gases during its manufacturing, according to the Global Cement and Concrete Association, a non-profit organisation.

As governments and companies look to cut planet-warming emissions, in line with the 2015 Paris Agreement goals to limit global temperature rise to "well under" two degrees Celsius (3.6 Fahrenheit), finding ways to "green" construction is key.

Mwanake said it was vital to boost visibility and awareness to grow her business, as many Kenyan consumers had a negative view about eco-friendly, recycled products.

"Unlike in Western countries where labelling a product as 'eco-friendly' is considered a positive by consumers and it is quickly snapped up, in Kenya it can be seen as a negative ... as if the product is of lower quality," said Mwanake.

"That view is slowly changing, but it is taking time," she said. "We know there is a market. We just have to reach it."