Abstract

The research studied effects of addition of kaolin clay on mechanical properties of sand moulds bonded with grades 1 and 2 Nigerian acacia species exudates. The properties included green and dry compressive strength; permeability and hardness; shatter index and the moisture content. Green and dry sand mould specimens bonded with composite mixtures of kaolin clay and each of grades 1 and 2 acacia exudates were subjected to the property tests using the universal strength and shatter index machines; permeability meter; hardness tester and moisture teller in foundry laboratory of Ajaokuta Steel Company Limited. The result when compared to previous works showed that addition of kaolin clay to acacia exudates improved green and dry strength of sand moulds over those bonded with plain grades 1 and 2 Nigerian acacia by about 25 and 40%; and moulds bonded with plain kaolin clay by about 54 and 11% respectively. It increased green permeability by about 15% and hardness by about 10%. The significance of the research lies in the fact that foundries would be availed with an alternative source of good sand binder from a blend of vegetable and mineral material, reducing total dependence on earth mineral that causes environmental degradation from mining. It would further promote reforestation through acacia tree plantations which would reduce ozone layer depletion and global warming for beneficial global climate change.

Key words: Nigerian acacia species, exudates, kaolin clay, sand, binder.