In 2024, Wales used 80,000 discarded diapers to build a road instead of sending 4 tons of waste to landfill

Most used diapers have a remarkably predictable journey: they are thrown away, collected and eventually sent to landfill.

But in one corner of Wales, thousands of them took a very different route.

In March 2024, Carmarthenshire County Council partnered with local recycling company Nappicycle to test whether materials recovered from used diapers could be incorporated into road construction. The trial on the B4336 at Pontweli used around four tons of used diapers — roughly 80,000 individual nappies — keeping that material out of landfill.


The experiment is particularly interesting because of the sheer scale of the waste problem it is trying to address.

Carmarthenshire collected 6 million diapers in one year

The four-ton road trial might sound modest, but it represents only a fraction of the diapers entering the local waste stream.

In 2023, Carmarthenshire collected approximately 6 million diapers.

Disposable diapers are challenging to recycle because they contain a mixture of materials, including plastics, cellulose fibers and absorbent components. Finding practical uses for the recovered materials could therefore make a meaningful difference if the process can eventually be expanded.

That is where Nappicycle's recycling process comes in.

From used diapers to fibrous pellets

The process began with the council collecting used diapers and sending them to Nappicycle's recycling facility in Capel Hendre.

At the facility, the diapers were processed and converted into fibrous pellets. Those recycled fibers were then transported to contractor GD Harries' plant in Ludchurch, where they could be incorporated into road-surfacing material.

The recycled fibers were mixed with Stone Mastic Asphalt (SMA), a type of asphalt commonly used for durable road surfaces.

According to the council, the recycled nappy fibers performed as effectively as conventional materials during the trial. Another encouraging detail was that the experiment did not result in an additional material cost.

That matters because an environmentally friendly material is much easier to scale when it does not automatically come with a higher price tag.

Why put diapers in a road?

The idea is essentially an example of the circular economy.

Instead of treating a used product as something that has reached the end of its useful life, the approach attempts to recover valuable materials and put them back into another system.

In this case, a material that would normally become waste was processed into fibers and incorporated into road construction.

That could have several potential benefits.

Keeping diapers out of landfill reduces the amount of waste requiring disposal. Using recovered fibers can also reduce the need for some virgin materials. And because the recycling and subsequent manufacturing took place locally, the project could potentially limit some of the transportation involved in moving waste and sourcing replacement materials.

The environmental gains should not be overstated, though. A trial demonstrating that recycled fibers can work in asphalt is not the same as proving that the process is automatically carbon-negative or environmentally superior in every circumstance. The overall impact depends on factors such as energy use, transportation, processing efficiency and how much conventional material can actually be replaced.

A small road trial with a much bigger question

For Carmarthenshire, the B4336 project is best viewed as a starting point rather than a finished solution.

The fundamental question is whether something as commonplace — and difficult to dispose of — as a used diaper can become a reliable source of material for infrastructure at a much larger scale.

Councilor Aled Vaughan Owen, Cabinet Member for Climate Change, Decarbonization and Sustainability, described the project as an example of environmental responsibility and innovation, emphasizing that used diapers could have a second life rather than simply being sent to landfill.

And the numbers make the experiment difficult to ignore.

Four tons of diapers became road material in one trial. Six million diapers were collected in the county in a single year.

If future trials continue to show that recovered diaper fibers can perform effectively in road construction without adding significant costs, the humble disposable diaper could become an unlikely part of the circular economy.

The bigger lesson may be even more interesting: sometimes the most useful recycling ideas begin by asking whether something we automatically call waste is actually just a resource in the wrong place.