Evaluation of bricks produced from a mix of sawdust-sand- cement as a potential construction material for low-cost housing in Uganda

Abstract

Increasing costs of sand bricks in Uganda is challenging many local communities to construct good family houses. A study was done to support low-cost construction by developing a sawdust-sand-brick that can replace sand bricks which is expensive. Sand-sawdust-bricks were produced in proportions of 25% and 50% sawdust mixed with sand and cement. The cement type was Portland cement (Pozzolanic cement type CEM IV B(P) 32.5 N (ISO 14001 2015) traded as Hima cement in Uganda. Two brick designs were made; a full solid brick design and and hollow bricks. The two brick designs were compared with purely sand and cement solid brick and hollow brick in terms of their physical and strength properties to enable recommendation of adoption for use in construction as replacements. The two brick designs were also subject to rapid ageing tests to determine their durability and structural integrity when exposed to service conditions. The physical properties evaluated were; water imbibition (Danielia et al., 2016), volumetric change (Swelling and shrinkage rate (%)) and density (ASTM D 1037-99). The strength properties evaluated were; modulus elasticity (Bowyer, 2003), modulus of rapture according to (ASTM D 1037-99), shear strength according to (Danielia et al., 2016), breaking strength and rapid ageing test in accordance to (Prachasaree et al., 2013). Full bricks exhibited, thickness swelling of less than 12% and acceptable water absorption characteristics that satisfy (BS 5628: Part 1: 2005). The full bricks with 25% sawdust MOE had a s mean 98 MPa which is insignificantly different from 100% sand brick with the process mean of 100 MPa, the full brick with 50% sawdust had a mean for MOE of 60 MPa which is a big value that can equally replace sand bricks for low-cost housing despite a slight reduction in strength, the maximum load required to break sawdust bricks ranged between 7000-12000MPa. Exposure to damp conditions and freezing has slightly less impact on strength of composites like the sand bricks and all bricks are not reduced in strength by temperatures. Therefore, the research concluded that Uganda can adopt use of wood-sand-cement composite bricks up to 50% gravel replacement level in construction because it gives comparable strength and can withstand rapid aging factors.