Bio-bricks: Biologically cemented sandstone bricks

• A novel technique to manufacture bio-bricks using a biologically mediated natural cementation process is presented.
• Results show that bio-bricks can have compressive strengths up to 2 MPa.
• P-wave velocity measurements show bio-brick stiffness to be relatively uniform and high.
• Bio-bricks are comparable to bricks prepared with the more conventional cement and hydraulic lime additives.

The cementation of sand into sandstone through microbial activity is a novel technology with a wide range of possible applications. The cementation process involves the introduction of bacteria and nutrients to sand, and through bacterial processes calcite precipitation binds particles together, ultimately creating a sandstone material. This technology could provide a new, more sustainable building material in the form of “bio-bricks”. This paper describes the treatment technique as well as results from testing after brick manufacturing. Bricks were tested to determine compression (p-wave) wave velocity, unconfined compression strength, and calcite concentration. P-wave velocity, stiffness, strength, and calcite content of bio-bricks all increase with further treatment of bacteria and cementation media. Results show that bio-bricks can have strengths ranging from 1 MPa to 2 MPa. Bio-bricks are comparable in terms of stress and stiffness to bricks prepared with the more conventional cement and hydraulic lime additives.