Used baby nappies that once went to landfill may now be given a more environmentally friendly second life. In a research paper published on 18 May scientists at Kitakyushu University in Japan, claim that nappies can partially replace sand in mortar and concrete composites used to construct buildings, without compromising their structural integrity.

The first house from used nappies has already been built in Indonesia. The diapers were first washed with sodium chloride, dried and then shredded before being added to composite mixes.

Lead researcher Siswanti Zuraida used her own children's nappies and also collected them from locals.

The researchers tested six different mixtures and concluded that concrete containing a different percentage of nappies could be safely used instead of sand in various aspects of construction.

A study published in the Scientific Reports journal claims that nappies can be used to replace up to 8% of the sand used during construction. Scientists believe that such a building material does not reduce the strength of the house. They point out that disposable nappies, which do not degrade, can become a cheap and accessible building material. Moreover, the reuse of nappies reduces their negative impact on the environment.

According to the study, nappies can replace:

• up to 40% concrete sand for non-bearing walls,
• up to 10% for columns and beams in a three-storey house,
• up to 27% for substructures in a single-storey house,
• up to 8% of all concrete and mortar used in the construction of an actual house of approximately 36sq m.

Sand is the second most consumed resource in the world (after water) and the most widely mined solid material on Earth. It is estimated that 50 billion tonnes of this material are consumed each year. Despite its abundance, the world is on the verge of a sand shortage due to the crucial role it plays in building infrastructure.