Geopolymer-Based Artificial Aggregates for Sustainable Pavement Construction: A Comprehensive Review

Abstract

The rapid expansion of the construction industry has significantly intensified the demand for natural aggregates, leading to unsustainable quarrying practices and severe environmental degradation, including biodiversity loss, water contamination, and adverse human health impacts. Simultaneously, the accumulation of industrial by-products such as fly ash presents a critical waste management challenge. In this context, geopolymer technology has emerged as a promising sustainable alternative, enabling the conversion of aluminosilicate-rich wastes into value-added construction materials. This study synthesizes existing research on manufacturing techniques and their influence on physical properties and engineering performance. Key process parameters such as production technique, alkaline activator composition, liquid-to-solid ratio, curing conditions are studied in relation to mechanical strength, water absorption, and durability characteristics. This review identifies critical research gaps such as high water absorption, limited precursor diversification and challenges in process scalability, ultimately providing a strategic roadmap for advancing sustainable construction materials in modern infrastructure development

Introduction

The text discusses two interconnected environmental problems: the increasing demand for natural construction aggregates due to rapid urbanization and infrastructure development, and the large-scale environmental pollution caused by industrial wastes like fly ash. Excessive quarrying of natural stone has led to land degradation, loss of agricultural productivity, biodiversity decline, groundwater disturbance, and severe human health issues such as respiratory diseases and noise-related disorders. At the same time, improper disposal of industrial by-products like fly ash contributes to air, soil, and water pollution due to its fine particulate nature and toxic leaching.

To address both challenges, the text highlights geopolymer-based artificial aggregates as a sustainable alternative. These materials are produced from industrial waste sources such as fly ash, slag, and metakaolin through geopolymerization, a chemical process that forms strong, durable aluminosilicate structures. This approach helps reduce reliance on natural aggregates while simultaneously recycling industrial waste, lowering environmental impact and carbon emissions.

The manufacturing of geopolymer artificial aggregates is mainly carried out using three techniques: pelletization, sintering, and autoclaving. Pelletization involves forming granules through mechanical agitation and binder action; sintering uses high temperatures to fuse materials into strong, lightweight aggregates; and autoclaving employs high-pressure steam curing to accelerate chemical reactions and improve strength. Each method has specific process conditions and advantages depending on the desired aggregate properties.

Conclusion

Geopolymer-based artificial aggregates present a sustainable alternative to natural aggregates by utilizing industrial by-products such as fly ash and GGBS, thereby addressing both resource depletion and waste management challenges. Their performance is strongly influenced by manufacturing techniques such as pelletization and cast-and-crush, along with precise control of chemical parameters. The properties of artificial aggregates are significantly enhanced by optimizing key factors, including the Na?SiO?/NaOH ratio of 2.5, optimum molarity of alkaline activators, controlled liquid-to-solid ratio, and appropriate curing regimes. Additionally, improvements in microstructure and durability can be achieved through precursor blending (e.g., FA–GGBS), finer particle size distribution, surface treatments, and advanced approaches such as nano-modification and fiber reinforcement, which reduce porosity and water absorption while increasing strength. Despite these improvements, challenges such as higher water absorption, durability and scalability remain. Future research focusing on standardized production, long-term performance, and advanced material optimization techniques will be critical to enabling the widespread adoption of geopolymer artificial aggregates in sustainable construction

References

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Copyright

Copyright © 2026 Nishikant Mehare , Divya Gangawane , Disha Ganjare , Sufiyan Shaikh , Kasturi Hate, Yash Bhamore , Mohd. Abdul Rehman . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.