Development of lightweight construction blocks by alkaline activation of bof slag

Large quantities of basic oxygen furnace (BOFS) are dumped in landfills of which the available land for land-filling of large quantities of waste is reducing all over the world. It is therefore important to develop processes which beneficiates solid waste; BOF slag specifically. The present study attempts to investigate the potential to synthesize BOF slag based light weight construction blocks. The effects of several factors on the UCS of BOF slag based light weight construction blocks (LWCB) was also investigated. The test variables were molarities of sodium hydroxide (NaOH) (5 M, 10 M and 15 M); the solid to liquid ratio (20 %, 25 % and 30 %); the sodium silicate (Na₂SiO₃) to NaOH ratio (0.5:1, 1:1, 1.5:1, 2:1, 2.5:1 and 3:1); the curing temperature (40°C, 80°C and 100°C). It was found that optimum synthesis conditions were 5M NaOH, 80°C and 1:1 Sodium Silicate: NaOH ratio. The LWCB composite met the minimum requirements for ASTM C34-13, C129-14a and South African standard (SANS227: 2007).