Mud House Failures and Mitigation Options in Bauchi, North East Nigeria

Abstract

The use of soil materials for sustainable construction in developing countries is a viable alternative to concrete based materials. The advantages include availability of soil (earth) materials, reduction of transportation cost, saved embodied energy, reduced environmental degradation and reduced material cost. Mud house collapse is a common yearly phenomenon in Nigeria. Much of this happens during rainy seasons due to flooding generated by heavy rainfall. Whenever this happened, people were rendered homeless and became Internally Displaced Persons (IDP), with the subsequent hardships and sufferings, and sometimes casualties. Sixty seven mud houses in three locations of Bauchi town, North East of Nigeria were investigated. From observations and returns from structured questionnaires filled by house owners and tenants, about 76% of the houses had failed in form of wall collapses alone. Other data collected included age of houses, composition of wall materials and foundations. Failures were generally severe and widespread for walls of full mud houses, however those plastered with cement/sand mortar had less failure counts. Older mud houses recorded higher failures as against new constructions. Soil samples collected from borrow pits used for the investigated mud houses were tested and their soil type compositions determined in the laboratory. They slightly fell short of the specified proportional limits of clay, silt and sand considered acceptable for construction purposes except stabilized. Sample bricks made from the soils were tested for compressive strength with an average value of 0.81N/mm2 which is far below the 2.5N/mm2 minimum value for sandcrete blocks specified by the Nigerian Standards Organization. Lack of good quality control measures and improper stabilization procedures, among others were considered responsible for the failed resistance to the environmental factors. Cement stabilization and good urban planning are some of the recommendations.