Human waste biochar in concrete production

Researchers are investigating the use of biochar derived from human waste to enhance concrete durability and reduce the environmental impact of cement production. Cement manufacturing is a significant contributor to climate change, accounting for approximately 88 percent of the concrete industry’s greenhouse gas emissions.

A study led by civil engineer Raghuvesh Tiwari at Manipal University Jaipur, published in ‘Scientific Reports’, details a process where human waste is dried and heated in low-oxygen environments to create a fine powder. Laboratory tests found that replacing 5% to 10% of cement with this biochar significantly improved material properties. Specifically, the 10% mixture achieved a 21% increase in compressive strength and a 42% increase in flexural strength after 91 days.

The biochar functions by creating microscopic water reservoirs that facilitate the formation of stable calcium silicates. While strength increases at lower replacement levels, researchers noted that strength began to decline at a 15% replacement level, indicating an optimal usage limit.