Performance Evaluation of Cement Grouts Using Industrial By-Products for Semi-Flexible Pavements

Semi-flexible pavement (SFP), a hybrid pavement system that combines open-graded asphalt with cementitious grout, offers enhanced durability, load-bearing capacity, and resistance to rutting compared to conventional pavement systems. However, the environmental impact of cement usage in grout formulations remains a significant concern due to its high carbon footprint. This study explores the feasibility of partially replacing ordinary Portland cement with industrial by-products, fly ash (FA) and silica fume (SF), in cement grouts for SFP applications. Grout mixtures with 5% and 10% replacements of FA and SF were prepared and evaluated for flowability, compressive strength (at 1, 7, and 28 days), and flexural strength (at 28 days). The study found that fly ash (FA) improves grout flow and long-term compressive strength, with 10% FA achieving a 16% increase at 28 days. Silica fume (SF) enhances both early and overall strength but reduces flowability at higher doses. Both additives improved flexural strength, with 5% FA showing a 28% increase over the target. Based on optimal flow (11–16 seconds) and compressive strength (60 MPa), the best performance was observed with 10% FA and 5% SF. These results suggest that FA and SF can serve as effective and sustainable partial replacements for cement, maintaining or enhancing mechanical performance while lowering environmental impact. This makes them suitable for use in semi-flexible pavement (SFP) applications, contributing to both durability and sustainability goals.