Strength and Durability of Biostabilised Ghanaian Mud Bricks

Communities in northern Ghana (Tamale and Wa) rely on earthen materials to construct affordable houses. However, these traditional practices are threatened by climate change: repeated flooding is triggering a transition to using cement-based building materials, and urban expansion and loss of biodiversity threaten the source of biostabilisers traditionally used to protect structures from water damage. Local builders currently rely on cementitious or bituminous renders to protect earthen houses, but these can trap water within the walls and so increase the likelihood of failure instead of protecting the buildings from harm. Such materials are, however, viewed as being prestigious and local people race to be able to apply them to their homes, creating a vicious cycle of earthen building degradation. This paper explores the possibility of using traditional Ghanaian biostabilisers dawadawa and beini in communities in northern Ghana to create water-resistant earth renders, to stabilise earth bricks and avoid the need for cement or bitumen. Methods used in Tamale and Wa to manufacture mud bricks were identified through field studies and used to recreate specimens in UK laboratories. The compressive strength and resistance to water (from immersion or dripping water) were tested for unstabilised bricks and bricks stabilised with a solution of dawadawa or beini. The results indicate that dawadawa can quadruple the resistance of mud bricks to water damage for no loss in mechanical properties, creating a strong incentive to protect and manage this resource.