Chemically altered soil could be used to build homes in developing nations

Soil-based construction materials could provide strong and environmentally-friendly housing in developing countries, scientists say.

Researchers are examining whether chemically altered soil, known as geopolymer-stabilised soil, could be used to build homes in some of the world’s poorest areas.

The material is created when alkaline chemicals, similar to those found in household cleaning products, are added to soil.

By adding the chemicals, clay present in the soil is transformed into a geopolymer – a kind of glue similar to cement, which chemically binds the material together.

University of Bath scientists say geopolymers can typically be fired at 80°C, whereas cement and fired bricks usually require more than 1000°C.

Alastair Marsh, from the university’s Department of Architecture and Civil Engineering, said: “The familiar construction materials of fired brick and concrete have a heavy environmental cost, with cement production alone accounting for 5-10% of global greenhouse gas emissions.

“Developing lower impact construction materials is an essential task to enable our world’s growing population to house ourselves adequately without contributing to climate change.

“Using this technology, a typical family home could be built using approximately 10 tonnes of soil, by adding 5-10% sodium hydroxide – a chemical similar to those found in household cleaning products – to geopolymerise the soil.”

Mr Marsh, a postgraduate researcher in civil engineering, said there is a significant knowledge gap in understanding how the geopolymerisation reaction works for different soil types

He is chemically and physically testing a range of soils with the process to determine whether these new materials could be used to build affordable and sustainable housing.

Depending on the materials and required properties, geopolymer-stabilised soils could have as little as half the carbon emissions impact of concrete, and a quarter that of fired bricks, he said.

Professor Andrew Heath, from the same university department, added: “This research is key to the development of sustainable housing around the world.”

 

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