Influence of Cement on the Pozzolanic Reactions of Ceramic Waste for the Stabilization of Ferralitic Soil in Road Construction

Abstract

This study investigates the influence of cement on the pozzolanic activation of pulverized ceramic waste (PCW) for the stabilization of ferralitic “Bar soil” from Tori-Dokanmey, Benin, for use in road construction. The soil, naturally rich in silica and alumina but poor in calcium, was combined with PCW (2.5–15%) and cement (1–3%) to develop 18 stabilized formulations. A comprehensive experimental program was conducted to evaluate the geotechnical and mechanical behavior of the mixtures, including compaction characteristics, unconfined compressive strength (Rc), flexural tensile strength (Rt), and stiffness parameters (E₅₀, Eₛₜ). Results show that the addition of PCW alone enhances soil density and bearing capacity through gradual pozzolanic reactions forming C–S–H and C–A–H gels, though strength development remains slow at early ages. The incorporation of small amounts of cement significantly accelerates these reactions, producing early strength gains and denser microstructures. Optimal performance was obtained for the mixture containing 15% PCW and 3% cement, with Rc = 6.5 MPa and Rt = 2.8 MPa after 90 days. The simultaneous increase in E₅₀ and Eₛₜ confirms improved stiffness and load-bearing capacity, indicating the suitability of the stabilized material for pavement foundation layers. Overall, the synergistic use of cement and ceramic waste provides a sustainable and efficient approach for upgrading local ferralitic soils while promoting waste valorization in road infrastructure.