Manipal University Jaipur researchers develop stronger concrete using human waste biochar

Researchers at Manipal University Jaipur in India have developed a more durable type of concrete by replacing a portion of cement with biochar derived from processed human waste. The study, led by civil engineer Raghuvesh Tiwari and published in the journal ‘Scientific Reports’, aims to reduce the environmental impact of cement production, which is a major source of carbon dioxide emissions.

The production process involves drying human waste and heating it in a low-oxygen environment at temperatures between 350 and 450 degrees Celsius to create a fine powder. In laboratory tests, this biochar replaced cement at levels of 5%, 10%, and 15%.

Results indicated that the addition of biochar significantly improved material properties. The highest strength was observed when 5% to 10% of the cement was replaced. Specifically, after 91 days, the 5% mixture showed a 20% increase in compressive strength and a 36% increase in flexural strength. The 10% mixture achieved a 21% increase in compressive strength and a 42% increase in flexural strength. The material also exhibited lower water absorption and reduced shrinkage. However, strength began to decline at the 15% replacement level, suggesting an optimal limit for usage.