Study on the use of cassava flour and local brewery waste (CETE) as a partial replacement of cement in masonry mortar.

Abstract

In this research, the possibility for use of cassava flour boiled in hot water in order to exploit the gelatinizing and retrogradation properties of starch and LBW (cete) in its natural or slurry form to partially replace cement in masonry mortar were studied through standard laboratory procedures to determine the chemical properties of cassava flour powder and LBW (cete), flexural and compressive strength, dry bulk density of hardened mortar and water absorption of the mortar cubes. The specimens were made using cement partially replaced with cassava flour and LBW (cete) at various replacement percentages (0% - 50%) and tested after 56days because of the retarding effects of the starch in the cassava flour and LBW (cete) which delayed the setting times of cement. The findings from this research reveal that, the dry hardened densities for both mortar blends were above 1300kg/m3, hence can be classified as heavy weight. Flexural strengths increased from 14.8MPa at 10% replacement to 17.2MPa at 20% before dropping to 13.3MPa at replacement 30% and 8.6MPa at 50% replacement for cement-cassava blend mortars while that for cement - LBW (cete) blends dropped from 12.5MPa at 10% replacement to 10.2MPa at 20% and 4.7MPa for 50% replacement. This clearly shows that mortar made from cassava flour blended with cement had better flexural strength compared to those made from LBW (cete) blended with cement. Compressive strength of mortars blended with cassava flour and LBW decreased with increase in the cassava flour and LBW contents. At 10% replacement, compressive strengths were 16.9MPa and 12.5MPa while at 50% compressive strengths were 7.1MPa and 5.6MPa for mortars blended with cassava flour and LBW (cete) respectively. These were above the compressive strength values for clay bricks 5.2MPa. Water absorption mortars blended with cassava flour increased from 4.0g/100cm2 at 0.25hrs to 18.0g/100cm2 after 24hrs for 0% replacement, 9.2g/100cm2 at 0.25hrs to 51.2g/100cm2 after 24hrs for 10% replacement and 71.4g/100cm2 at 0.25hrs to 156.6g/100cm2 after 24hrs for 50% replacement and mortars blended with LBW had 14.0g/100cm2 after 0.25hrs to 73.6g/100cm2 after 24hrs for 10% replacement and 77.4g/100cm2 after 0.25hrs to 188.6g/100cm2 after 24hrs for 50%. Generally, mortar blended with cassava flour had lower water absorption compared to mortar blends made from LBW (cete). In conclusion, both cassava flour and LBW (cete) have potential for use to partially replace cement in construction of houses.