Kaolin Valorisation as a Raw Material of Geopolymer Cement for Road Pavement Construction Used for Stabilizing Untreated Gravel

Abstract

Road construction plays a vital role in a nation's development. However, increased traffic loads and road pavement degradation have led to the adoption of innovative materials, such as geopolymer cement (GPC), to address environmental concerns associated with conventional cement usage. GPC, produced through a chemical reaction involving alkali hydroxide, silicate, and aluminosilicate precursors, offers a solution to reduce carbon dioxide emissions and utilize low CO₂ emission technics. This study focuses on gravel treatment by alkali-activated metakaolin as the geopolymer precursor and activated with a mixture of sodium silicate and sodium hydroxide. Laboratory tests, including modified Proctor compaction, California Bearing Ratio (CBR), and unconfined compressive strength assessments, were performed with different NaOH dosages (8, 10, and 12 moles) in geopolymer-treated gravel. The results showed that geopolymer-treated gravel outperformed conventional cement-treated gravel, exhibiting higher dry density and unconfined compressive strength while meeting road foundation layer design standards. This research found that metakaolin-based geopolymer cement can substitut Portland cement in gravel treatment used in flexible pavement base layers, offering a sustainable alternative for road infrastructure development.