Urine-Based Bio Concrete: A Sustainable Building Material from Human Waste

Brief

Learn how urine-based bio concrete is transforming human waste into a sustainable construction material through microbial innovation.

Insight

Bio concrete is reshaping the future of construction by offering an eco-conscious alternative to traditional cement. Scientists at the University of Stuttgart have successfully developed urine-based bio concrete through a microbial process called biomineralisation, turning human waste into a valuable building resource. This innovation not only reduces the environmental impact of cement production but also supports a circular economy by recycling waste into usable materials.

The process involves mixing sand with a bacterial powder, then flushing the mixture with calcium-enriched urine. Over three days, bacteria break down the urea, facilitating the growth of calcium carbonate crystals that bind the mixture into a solid form. The result mimics natural calcareous sandstone and eliminates the high-temperature energy demands of conventional cement, drastically lowering carbon emissions.

Urine—typically discarded as waste—is the key raw material. The researchers experimented with synthetic and real human urine. When using technical urea, the concrete reached over 50 megapascals in compressive strength, while real urine yielded up to 5 megapascals. The challenge now lies in improving bacterial durability to increase strength when real urine is used. A compressive strength of 30–40 megapascals is the target, making the material suitable for two- to three-storey buildings.

This project, named SimBioZe, goes beyond innovation in building materials. It integrates a circular value chain where human urine, rich in nutrients and water, is collected at high-footfall sites like airports. From this single input, both bio concrete and agricultural fertiliser are produced—demonstrating a dual-purpose, zero-waste system.

With funding from the Baden-Württemberg Ministry of Science, the project is now entering its second phase: optimising production and conducting field trials at Stuttgart Airport. Collaborations with academic and industrial partners, including the University of Hohenheim and the Centre for Organic Farming, aim to bring this sustainable construction method into practical use, offering a glimpse into a greener future for civil engineering and architecture.

Highlight

Scientists at the University of Stuttgart have successfully developed urine-based bio concrete through a microbial process called biomineralisation, turning human waste into a valuable building resource.
The process involves mixing sand with a bacterial powder, then flushing the mixture with calcium-enriched urine. Over three days, bacteria break down the urea, facilitating the growth of calcium carbonate crystals that bind the mixture into a solid form.
When using technical urea, the concrete reached over 50 megapascals in compressive strength, while real urine yielded up to 5 megapascals.