A PhD student used shredded baby diapers in a prototype Indonesian house; 27% of its non-structural concrete blocks contained diaper waste, totaling about 3,700 pounds

Somewhere in Indonesia is a small, ordinary-looking house, about the size of two parking spots. Two bedrooms, one bathroom, one floor, nothing out of the ordinary. However, inside its walls and concrete blocks is something you would never guess by looking: almost 3,700 pounds of used diapers. Siswanti Zuraida was a PhD student in architectural engineering at the University of Kitakyushu, Japan, when she became the lead author of the 2023 study, 'Application of non-degradable waste as building material for low-cost housing,' published in Scientific Reports. Zuraida started her experiments at home. She washed and dried her baby's used diapers, left them out in the sun for a month, then shredded them by hand with scissors. The concept for the project, and some of its funding, later came from an Indonesian renewable energy and waste-management consultancy that collaborated with her team. That small, odd beginning eventually grew into a full research program, with her team scaling up diaper collection and processing well beyond her own household, and finally resulted in a completed, livable house.

Two problems, one shared root

These are two problems that bothered Zuraida. Firstly, disposable diapers can take decades to decompose in landfills. Secondly, concrete is the main building material for most houses, and it depends heavily on sand, a resource the world is using faster than nature can replace it. The United Nations Environment Programme reported in 2019 that the world consumes 40 to 50 billion tonnes of sand and gravel annually, only second to water in consumption among extracted resources. Such high demand for sand leads to depletion of rivers, degradation of coasts, and environmental damage.


Concrete poses yet another problem as well. The main component of concrete is cement, which is responsible for at least 8% of the world’s carbon dioxide emissions, as Nature's editorial team explained in a 2021 piece titled ‘Concrete needs to lose its colossal carbon footprint.’ The editorial says cement production requires limestone and clay heated to very high temperatures, releasing large amounts of carbon dioxide. Zuraida wondered if diaper waste, which is mostly plastic fibers and cellulose, could replace some of that sand.

Turning trash into building material

With her team, Zuraida mixed the shredded diapers with cement, sand, gravel, and water to produce samples of both concrete and mortar. These samples were allowed to sit for 28 days before being subjected to crushing in order to determine their load-bearing capacity. The results showed a pattern: concrete strength decreased as more diapers were added. So the team mapped out where diaper waste could go safely. Non-load-bearing walls and panels could contain up to 40% diaper waste, while load-bearing walls and columns were limited to 9% to 10%.

From lab samples to an actual house

After the ratios had been determined, Zuraida teamed up with the architects and engineers from Indonesia to create a prototype of a house that was compliant with the country's building regulations. The final structure relied on metal beams for its load-bearing elements, while its non-structural concrete blocks were made with 27% diaper waste, which the team estimated added up to nearly 3,700 pounds of shredded diapers across the build. Indonesia was not selected at random. Nearly 70% of the country's population will live in urban areas by 2025, and the nation's housing shortage grows by an estimated 300,000 units a year, adding to the waste problem.

Diapers have done this before, just not for houses

Zuraida's project wasn’t the first time someone thought of giving used diapers a second life. In Wales, a company called NappiCycle collected more than 100,000 used diapers in 2022 and used them to pave roads. In 2019, Amsterdam piloted diaper collection using special bins installed in pharmacies and nurseries. Similar efforts have been made in Belgium and Italy. While they have not constructed buildings from the waste, they suggest the material can be reused in construction-related applications.

Why the process is not ready for widespread use

You won't see this being rolled out in your neighborhood next year. For now, the process remains a small, manually controlled experiment rather than a manufacturing-scale system. For it to work outside a laboratory setting, cities would need infrastructure to collect and sanitize used diapers. There is also a technical hurdle: the small-scale, hand-shredding process used in the lab would need industrial machinery to scale up, and cities would need infrastructure to collect and sanitize diaper waste before it could be reused, capabilities currently limited to a handful of developed countries. Moreover, building codes in Indonesia, and in many other countries, still limit approved construction materials to a short list, such as concrete, bricks, wood and ceramics. That means a new material such as diaper-based concrete still faces regulatory hurdles before it can be used more widely in homes.

The takeaway

For now, Zuraida’s little house in Indonesia is a proof of concept rather than a solution. It shows how an ordinary and unglamorous used diaper may actually find its way into the construction of houses worldwide that will be affordable and yet won’t require so much sand as before. It suggests that climate-friendly innovation doesn't always start in a fancy lab. Sometimes it starts with a parent and a pile of laundry and a question no one else thought to ask.