Assessment of artisan clay bricks on performance of structural strength, chemical stability and durability in Uganda

Abstract

Bricks are oldest building materials since 7000BC, and are preferred as building material due to their high compressive strength, fire & weather resistance, thermal & sound insulation and durability. l11e artisan clay bricks in Uganda are characterised with low strength, erosion, tiny cracks, lime pop out, warping, efflorescence and high-water absorption. The raw clay and artisan burnt clay brick samples were collected from artisan brick making places (sites) from Eastern, Central and orthcrn Uganda. The sampling was done using JS-5454 procedures. Testing was carried out for water absorption, mineral percentage investigation in natural and purified clay in terms of sio2, Ah03, Fe203 & CaO, compressive strength of the artisan clay unit, improved chemical composition artisan clay units from purified clay and improved molded bricks from raw clay. Results indicated that mineral requirements for manufacturing bricks was not satisfactory; for artisan bricks, they had very low characteristic strengths of 0.63N/mm2 for Lira and 0.38N/mm2 for Mukono samples. Refining and change on molding process was done and the raw clay structure shifted to the positive side of the required mineralogy. Fired bricks on testing gave higher characteristic strengths of 2.2 N/mm2 after purifying and 3.3N/mm2 after use of improved mold for Lira, 5.12 and 2.62N/mm2 respectively for Mukono, slight efflorescence and low water absorption. This study therefore recommend that the artisan do include both clay refining processing and constant force kneaded clay pressing in the manufacturing process. Key words: Strength, brick structure, chemical stability and durability in Uganda