In the search for environmentally friendly building materials, scientists have landed on used diapers. Washed, disinfected, dried and shredded, they could replace up to 27 percent of the sand in concrete and up to 40 percent of the sand in mortar in structural parts of a one-story house, writes a research group led by Siswanti Zuraida of Kitakyushu University (Japan). in the science journal Scientific Reports. The building regulations in Indonesia were used as a basis.
“Building materials are often the most significant physical contribution to the construction of homes and can account for up to 80 percent of the total value of a basic dwelling,” the authors write. Cost is the first barrier to sustainable construction in low- and middle-income countries. Due to the annual population growth of 4.1 percent, around 780,000 new housing units are needed in Indonesia every year, but the construction industry can only create a maximum of 500,000.
In non-load-bearing walls, the proportion of diapers in the mortar can rise to 40 percent
With the used disposable diapers, Zuraida and colleagues therefore tested an alternative construction material that would also relieve landfill sites. To do this, they made concrete mixtures with different proportions of diapers instead of sand. They allowed the mixtures to cure for 28 days and then tested their compressive strength. Using Indonesian building codes, they then determined which parts of the house could hold what proportion of diapers without sacrificing the strength needed.
In a three-storey house, the compressive strength of the load-bearing elements, such as pillars and beams, must not fall below 20 megapascals. That is why the fine grain content in them can be replaced by diapers up to a maximum of ten percent. It is up to 19 percent for a two-story house and up to 27 percent for a one-story house. In masonry, non-load-bearing walls, on the other hand, the proportion of diapers in the mortar can rise to 40 percent. In the mortar for floor slabs, in the house or on the terrace, diapers can replace up to 9 percent of the sand.
Zuraida and colleagues calculated that for a living area of 36 square meters with a building material requirement of 22.79 cubic meters, 1.73 cubic meters of diaper waste can be used. However, this is not easy to implement in Indonesia. On the one hand, there are no companies there that use disposable diapers as recycling material. On the other hand, the country’s current building regulations would prevent the use of diapers in concrete and mortar. This probably applies to most other countries as well.