In an attempt to solve two environmental problems at once, researchers at the University of Kitakyushu in Japan replaced 9-40% of the sand used to make concrete with shredded diapers without reducing its strength. I have discovered that it is possible. Disposable diapers are a growing source of non-recyclable waste, and cement production accounts for nearly 7% of global greenhouse gas emissions and consumes about 50 billion tons of sand each year.
Diaper-infused concrete is used to build tiny homes in Indonesia, diverting this kind of waste from landfills to build more affordable housing in low- and middle-income communities. I have proven the method.
Ciswanti Zuraida, a civil engineer at Kitakyushu City University, started the project during a lecture at the Bandung Institute of Science and Technology near Jakarta. Populations in wealthy countries often plateau and decline, while populations in Indonesia and other low- and middle-income countries continue to grow, resulting in more babies, more diapers, and lower costs. Demand for housing will increase.
“The key is resource availability,” says Zuraida. “As the population grows, so does diaper waste.
Disposable diapers are typically made from wood pulp, cotton, and superabsorbent polymers, and small amounts of polymer have been found to improve the mechanical properties of concrete. With funding from a Jakarta-based waste management company called Awina, Zuraida wondered how much sand could be used instead of shredded diapers to make useful concrete or mortar. I started looking.
near the house
Initially, the researchers sourced diapers locally. Zuraida has a toddler. After washing, drying and shredding the diapers, the resulting material was mixed with cement, sand, gravel and water. The team tested various formulations to replace up to 40% of the sand in concrete.
After curing for one month, the samples were pressure tested to determine the rupture point of the composite. From these measurements, Zuraida and his colleagues calculated the maximum percentage of diaper waste to meet building component needs.
The more diaper crumbs in the concrete, the lower the compressive strength. Structural components such as columns and beams therefore require less shredded diaper percentage than architectural elements such as walls and concrete blocks. The researchers calculated that 27% of the sand could be replaced with diaper waste in the prototype one-story house. But if the house is his three-story, the percentage he should drop to 10%.
In building components, up to 40% of sand can be replaced by diaper waste, with concrete wall panels having the highest percentage. In flooring and garden paving, which need to be stronger than walls to meet building codes, diapers can replace as little as 9% of sand.
house built by diapers
The researchers then used diaper-infused concrete to build an experimental house in accordance with Indonesian building codes. The house was small; The floor plan is just 36 sqm and has about 2.5 parking spaces. To speed up the building process, the researchers used nappy concrete for the building components and metal beams for the structural components.
In total, the house used about 1.7 cubic meters of diaper waste, which accounted for about 8% of the total composite volume.
Christoph Schleefl, a chemist who studies sustainable building materials at the Technical University of Dresden in Germany, said of how to extract value from non-degradable waste: It is a work with a
However, transporting diaper waste to a processing plant or construction site could “create a fairly long transportation path,” and if the team wanted to make their low-cost housing more environmentally friendly, wooden walls could be an option. There is a risk, he warns. Based on composite materials instead of concrete.
Zuraida agrees that separating diapers from the waste stream is the most difficult part of translating her work into the real world. Indonesia will generate 20 million tons of waste in 2021, of which about 10% of plastic will be recycled. “Municipal waste management does not have a support system for sorting diapers,” says Zuraida. “Plastic bottles are fairly easy to recycle, so they are currently segregated, but diapers are usually sent to the incineration process.”
This article is reprinted with permission and was first published on May 20, 2023.
