Utilization of bauxite tailings as partial replacement of sand in blocks

Abstract

Disposal of bauxite tailings in Ghana and globally is not properly managed and leads to environmental degradation. There is possibility for their recycle to facilitate proper disposal, one way is to partially replace sand with bauxite tailings in building blocks. A study was carried out on cement composite blocks made from sand and bauxite tailings/residue, a mining by-product at varying levels from 10% to 50% with incremental level of 10%. Composite blocks were produced to dimensions of 150mm × 150mm × 150mm for the various replacement levels consisting of 0%, 10%, 20%, 30%, 40% and 50% by weight of sand. A total of 120 blocks were produced and tested for their densities, compressive strengths, and resistance to abrasion and water absorption after 28 day of curing. Results from the study showed that composite blocks with the bauxite tailings replacing up to 20% of the sand content recorded the highest compression strength, lowest abrasion loss with the least water permeability. Even though, there was a general decline in the properties of the composite blocks with bauxite tailings replacement beyond 20%, blocks produced satisfied the minimum requirements for blocks for wall construction. The compressive strength of the composite blocks saw a significant decline from 15.907N/mm2 to 8.427N/mm2 as the bauxite tailings content increased beyond 20% up to 50%. It was observed that there was a systematic fall in the average dry densities of the blocks as the quantity of bauxite residue was increased. Comparatively, the composite with B50 grade was 14.16% lesser dense than the control block. It was evident that abrasion loss significantly increases as the quantity of bauxite residues increases beyond 20% replacement in the composite blocks. The addition of bauxite tailing content thus resulted in lower migration of water into the block (i e. lower permeability). A strong correlation existed between the composite blocks produced from the different batches and the properties of the blocks studied. The results indicate that at the replacement level of 20%, the bauxite tailings have a good potential for use as a masonry material for wall construction.