Valorization of de-oiled sesame and sunflower seed residues as sustainable alternatives to limestone and supplementary cementitious materials in cement matrices

Abstract

Limestone and coal scarcity demands alternative cement materials, yet agricultural-residues remain underexplored for dual-purpose as biofuel → limestone/SCM. This study investigates de-oiled seed cakes (DSCs) from sesame and sunflower as biofuels and their combustion residues, de-oiled seed ashes (DSAs), as cementitious materials. DSCs exhibited calorific values of 4740–5217 kcal/kg and 20.85%–21.80% of ash, confirming biofuel suitability. XRF revealed CaO contents of 60.60% in DSA-S and 17.37% in DSA-SF, with SiO<inf>2</inf> (6.53%) and Al<inf>2</inf>O<inf>3</inf> (2.99%) in DSA-SF. XRD and FTIR confirmed calcite in DSA-S, while kalsilite and SiO<inf>2</inf> were detected in DSA-SF. TGA demonstrated thermal stability with decomposition at 955 °C and 1163 °C. Physical properties including consistency, setting time, fineness, specific gravity, and soundness were satisfactory. DSA-SF contains high K<inf>2</inf>O (30.78%), requiring ASR mitigation consideration. Pozzolanicity was assessed through Frattini and Strength activity index tests. DSAs achieved compressive strength exceeding 80% of control at 20% OPC replacement, demonstrating dual-purpose potential supporting circular resource utilization. © 2025 Informa UK Limited, trading as Taylor & Francis Group.