UBC study looks to strengthen rammed earth construction

Barreto (left) and Siddiqua (right).

Compressed soil, or rammed earth, is the focus of a study out of the University of British Columbia (UBC) Okanagan campus.

The use of soil as a construction material may offer a reduction in costs and energy consumption, according to Sumi Siddiqua, engineering professor at UBC Okanagan.

“Conventional cement construction is the principal building material for buildings, roads, pipelines and bridges around the world,” said Siddiqua. “But builders today are seeking cheaper and more environmentally responsible construction materials.”

Soil is natural and locally sourced, and can be used to create rammed earth walls, earth bricks and compressed earth blocks. Rammed earth walls are usually placed between molds and bound by clay.

Siddiqua and her graduate student Priscila Barreto tested the addition of calcium carbide residue and fly ash as binding agents in the rammed earth.

They found that when cured for 60 days, the walls containing binding agents were 25 times stronger than those without.

Siddiqua said there is a demand for this type of material and the technique has been used in small cities in Canada, including in small residential homes in Okanagan.

“We targeted rammed earth structures because local construction engineers have approached us looking to improve traditional rammed earth structures with stabilization techniques,” said Siddiqua.

The research was published in the journal Construction and Building Materials, and was supported by both a Discovery and Engage Grant from the Natural Sciences and Engineering Council of Canada.