Stabilization for Low-Cost Housing Construction:
This applied research paper is aimed at improving the quality of mud bricks using low-cost stabilization and compression techniques. The soil used in this study was obtained in Damboa and Ngala local government areas of Borno State, Northeast Nigeria. For this research, ordinary Portland cement and local straws (Gamba grass and Chaqqa) were used as partial replacements for clay soil by mass in the production of mud bricks. The replacement percentages used were 0%, 2.5%, 5%, and 7.5% for cement replacement, and 0.1%, 0.3%, and 0.5% for straw replacement. Compressive strength and water absorption tests were performed in accordance with British Standard (BS) 3921:1985 to determine its suitability as a building material.
The compressive strength and water resistance of the mud brick samples increased considerably with an increase in cement and straw replacements at 28 28-day curing period. Therefore, the stabilized compressed earth bricks (SCEB) technique has improved the quality of local mud bricks in the study area. This applied research, funded by USAID-Bureau of Humanitarian Assistance (BHA) under the program, Addressing Diverse and Acute Primary Threats to Human Security in Northeast Nigeria (ADAPT) was conducted by Mercy Corps Nigeria, in collaboration with the University of Maiduguri and Ramat Polytechnic.
The continuous displacement of vulnerable people and destruction of shelters and household assets due to the insurgency continue to be the main drivers for shelter needs across Borno, Yobe, and Adamawa states. The lack of adequate shelter exposes the most vulnerable people to significant protection risks threatening their dignity, physical well-being, and living standards. Shelter needs remain high even after a number of years of humanitarian action since emergency shelters provided for IDPs have a short life span of six months and do not provide beneficiaries sufficient protection from the environment, are highly prone to wear and tear, and require periodic replacement to some provide privacy, dignity, and security.
The human population is growing faster than people can afford to build houses, thus creating a housing shortage. In many countries like Nigeria, an average citizen cannot afford the cost of constructing a modest accommodation. It is therefore imperative to source innovative and sustainable techniques to make low-cost and effective building materials available.
Mud brick, an affordable low-cost building material made from the abundantly available lateritic soil, has associated problems with some of its properties, hence must be modified to ensure its suitability. The identified issues with mud brick include compressive strength and water resistance which leads to durability problems, for instance, perforation of the walls and gradual erosion of the brick building.
Lateritic soil in its natural state generally has low bearing capacity and strength due to its high clay content. When lateritic soil contains a large amount of clay materials, its strength and stability cannot be guaranteed under load, especially in the presence of moisture.
Mercy Corps conducted housing typology surveys in Dikwa, Damboa, Ngala, Bama, and Gwoza local government areas of Northeast Nigeria from 2018 to 2019. The surveys showed that mud bricks are among the abundantly used, self-produced, and economical construction materials. The bricks have helped the IDPs, returnees, and the host to repair their completely damaged shelters economically, compared to cement blocks that cost 20-25 times more depending on the location.
Mud blocks are in high demand for the major damaged shelters in rural areas. Skills for casting these bricks are abundant in the rural LGAs, moreover, self-builders are also busy making these bricks for their shelter repairs as observed in Mercy Corps areas of operations. The use of locally available stabilizers such as straws, husks and crushed dry leaves that act as a reinforcement to some extent, have also been observed. However, overall, the mud bricks observed in the field have poor quality.
These poor-quality bricks don’t last long under heavy rains and rain shortens the life of a mud block structure. Mercy Corps sees the critical need to take care of the mud bricks used in recovery efforts to ensure ongoing self-recovery and self-building efforts are sustainable.