Enhancing the adoption of interlocking stabilized soil blocks for affordable housing in Uganda : a comparative study with alternative masonry products

Abstract

This research study was performed to evaluate the viability of Interlocking Stabilized Soil Blocks (ISSBs) as an alternative to conventional masonry materials in Uganda, focusing on their structural performance, thermal efficiency, and cost-effectiveness. The main objective was to assess the potential of Interlocking Stabilized Soil Blocks in promoting affordable and sustainable housing in Uganda. Specifically, the objectives were: To analyze the structural performance of ISSBs under the differing environmental conditions prevalent in Uganda, to explore the impacts of ISSBs on energy efficiency in buildings, and to evaluate the cost-effectiveness of ISSBs in comparison to the conventional masonry products used in Uganda. ISSBs performed considerably better than traditional clay and mud bricks in both strength and durability, under differing conditions, that is, dry and wet conditions. With a dry compressive strength of 3.99 MPa, ISSBs were 109% stronger than clay blocks and 39% stronger than mud bricks. Though slightly below the strength of concrete blocks (4.73 MPa), ISSBs retained nearly 78% of their strength after 24 hours of water immersion, outperforming mud bricks and closely matching concrete’s performance in wet conditions. Water absorption tests showed that ISSBs absorbed 14.07% water after 72 hours lower than clay and mud bricks, though higher than concrete. In terms of energy efficiency, ISSBs recorded the lowest thermal conductivity (0.354 W/m·K) among the masonry products tested, making them the most efficient insulator. This characteristic suggests significant potential for reducing indoor temperatures and lowering energy demands for cooling, particularly in Uganda’s hot and humid climate. Cost analysis per cubic meter of walling placed ISSBs at UGX 219,000 more affordable than concrete (UGX 230,158) and clay blocks (UGX 269,812), and only slightly more than mud bricks (UGX 188,565). The cost advantages are further reinforced by the block’s interlocking design, which eliminates the need for mortar, reduces labour input. ISSBs are a technically sound, thermally efficient, and economically viable building material. Their adoption can contribute meaningfully to affordable and sustainable construction in Uganda, provided current barriers such as the lack of formal standards and social acceptance are addressed through targeted policy, technical support, and public sensitization.