Could poo be used to make roads and buildings?

Scientists have found that human poo can be turned into a useful material to make stronger, more environmentally-friendly concrete.

Concrete is used in building everything from schools and houses, to roads and bridges.

The process involves waste being collected from sewage treatment plants and turned into biochar – a material a bit like charcoal - by heating it up.

Normally concrete is made by mixing cement and water, with gravel or crushed stone, which fill small gaps and provide strength.

But in this experiment, researchers replaced some of the cement in the concrete mixture with biochar and found it did an even better job.

However before poo can start being used in this way, the researchers say more work is needed to assess how it performs under real-world conditions.

The team of researchers were led by civil engineer Raghuvesh Tiwari of Manipal University Jaipur in India.

The researchers used the biochar powder to first replace 5%, than 10% and 15% of cement in conventional concrete, and put it through a series of tests to see how well it compared to the original.

The results, published in the journal Scientific Reports, showed that the strongest concrete was generally produced when 5% of the cement was replaced with biochar, and continued to gain strength as it dried.

The researchers found that the concrete containing biochar could perform similarly to normal concrete when it came to water absorption and shrinkage.

This suggests that using biochar doesn't necessarily make the concrete less durable or more likely to change shape over time.

The biochar also appeared to reduce the amount of heavy metals that could potentially come out of the concrete, which could make it safer for the environment.