Compacted Foundry Sand Treated with Bagasse Ash As Hydraulic Barrier Material

Laboratory tests were conducted on foundry waste sand treated with up to 8% bagasse ash (a pozzolana) by dry weight of soil to assess its suitability for use in a waste containment application. Specimens were prepared at molding water contents - 2, 0, +2 and +4% of the optimum moisture content using British Standard light, BSL (standard Proctor) compactive effort. Index properties, hydraulic conductivity (k), volumetric shrinkage strain (VSS) and unconfined compressive strength (UCS) tests were carried out. Results obtained showed no significant change in index properties. However, hydraulic conductivity values recorded for 2 and 4% bagasse ash treatment met the regulatory 1 x 10^–9m/s requirement. Specimens treated with a minimum of 4% bagasse ash met the minimum UCS value of 200 kN/m² requirement. VSS values recorded met the regulatory requirement of less than 4% for specimens treated with a minimum 2% bagasse ash content. The overall acceptable zone for bagasse ash treated foundry sand for use in waste containment application was achieved with 4% bagasse ash content. However, the molding water range 11.2 – 12.6%. is too narrow for practical purpose. It is recommended that the activity of bentonite in foundry sand be recovered rather than addition of bagasse ash.