Utilization of Waste Glass, Fly Ash, Metakaolin and Silica fumes in Paver Blocks

Abstract

The waste coming out of thermal power plants and during the production of silica and its alloys results in a large amount of waste that requires disposal in controlled landfills. Consequently, the financial and environmental costs of landfilling are very high. However, these byproducts/waste can be used as supplementary cementitious material (SCM) instead of being disposed or landfilled. Similarly, waste cullet can also be used as the supplementary material in concrete paver blocks as a partial replacement of sand. Therefore, this study aimed at developing an eco-friendly precast concrete product by enhancing the application of waste glass, fly ash, metakaolin and silica fumes. The waste glass was utilized as a partial replacement of sand. Fly ash, metakaolin and silica fumes is utilized as a partial replacement of cement in the paver blocks. It is observed that for a constant water-to-cement ratio, compressive strength increases with the partial replacement of cement with waste supplementary cementitious materials. The highest increase in strength is at the 15% replacement of cement with fly ash, silica fumes and metakaolin. On the other hand, in case of replacement of natural sand with glass cullet, highest increase in the strength is obtained at the replacement level of 10%. The flexural strength of the paver blocks increases with addition of glass cullet, fly ash, metakaolin, silica fumes is added in the mix. The maximum increase in the flexural strength is observed in the specimens in which 15% cement is replaced with supplementary cementitious material. On the other hand, 10% replacement of sand with glass cullet the flexural strength obtained is higher than other replacement level. In case of blocks having partial replacement of cement and sand, highest flexural strength is obtained when the replacement level of cement is with 15% fly ash and 10% sand is replaced with glass cullet. The most importantly, enhancement in the strength is double as compared to the controlled specimens. The water absorption coefficient obtained for all the mix is well below the IS: 15658 (2006) specifications. So, all the mixes pass the Indian standards for water absorption test. The combined use of glass cullet and pozzolanic waste materials was beneficial in reducing the water absorption paving blocks within permissible limits. Moreover, the addition of waste materials also enhances the flexural and compressive strength of the paving blocks.