Strength Development of Artificial Aggregate Manufactured from Geopolymerization of Waste Materials

The construction industry's rapid growth worldwide has led to a higher demand for construction materials for new infrastructures, but this growth has come at a cost to the environment. The depletion of natural aggregates has led to attempts to explore the use of waste materials to produce artificial aggregates. Waste minimization and recycling have also become crucial issues in the twenty-first century. This study focuses on the potential of using waste materials, such as sewage sludge ash (SSA), medical waste incineration ash (MWIA), and coal-based fly ash (CFA), to produce artificial aggregates through geopolymerization. The study utilized three combinations of these materials activated with sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). The resulting samples were compacted by auto compaction, cured for 28 days with an initial 24-h heat cure, and then manually crushed to produce aggregates. The characteristics of the resulting aggregates were evaluated through various tests including specific gravity, water absorption, aggregate impact value, and crushing index. The study found that the sample with a ratio of MWIA:SSA:CFA of 1:1:1 demonstrated the highest crushing index, which was 97% higher than the brick chips used as the control specimen. The sample with a ratio of MWIA:SSA:CFA of 1:1:0 performed better in terms of engineering properties, with the lowest aggregate impact value and the lowest water absorption. The findings of this study suggest that utilizing waste materials to produce artificial aggregates could be a sustainable and eco-friendly way to replace natural aggregates in construction projects.