Cob bricks for sustainable building

In an effort to make the low-carbon biomaterial more accessible, researcher Tavs Jorgensen created a method of extruding cob into brick shapes.

The process involves pushing different samples of cob, a construction material made from earth and straw, through 3D-printed extrusion moulds to create bricks that can be stacked in interlocking patterns.

The method was developed in 2024 as part of a research project at the University of the West of England’s Centre for Print Research, where Jorgensen is an associate professor.

People have used cob as a natural and ancient building material for thousands of years. They make it by combining subsoil, water and fibrous materials such as straw.

Jorgensen’s research was initially focused on exploring other clay-based materials for various applications. However, he was drawn to cob construction due to the growing importance and need for sustainable building techniques.

Cob is typically considered a labour-intensive construction process. It is traditionally formed into monolithic walls and compressed. Jorgensen hopes that making the biomaterial available as a brick will increase its accessibility.

Several cob mixtures were created to determine the most suitable composition for the extrusion process, and Jorgensen has developed both light and heavy versions of the bricks.

Light cob bricks are made with two parts liquid clay and three parts hemp shiv, which is the woody core of the hemp plant. Meanwhile, the heavier bricks are made with a mixture of one part sand and one part clay, which is then added to barley straw and water.

Jorgensen, whose research is supported by the Arts and Humanities Research Council and funded by Research England’s Expanding Excellence in England programme, hopes to encourage the industrial uptake of earth-based building techniques, thereby lessening the environmental impact of construction.

Source: Dezeen