Muhammad Akbar Caronge, Nevy Sandra, Jati Sunaryati, M.W. Tjaronge, Muhammad Anshari Caronge, Kazuaki Nishimura, Nurul Hudaya
This study investigates the feasibility of valorizing Sulawesian ferronickel slag (FNS) powder as a supplementary cementitious material (SCM) for sustainable mortar production. Ordinary Portland cement (OPC) was partially replaced with FNS at levels of 0–35% (at interval of 5%) by weight, and mixtures were evaluated for fresh density, consistency, setting time, compressive strength, strength activity index (SAI), ultrasonic pulse velocity (UPV), microstructure, and life cycle assessment (LCA). Results showed that consistency slightly decreased with higher FNS substitution, while setting times increased proportionally, with each 1% replacement extending the initial and final setting times by 1.5 and 2.6 min, respectively. Fresh density declined linearly from 2366.67 kg/m3 (control) to 2048.53 kg/m3 (35% FNS), representing a 13.45% reduction. Compressive strength remained comparable to the control up to 10% replacement, achieving 28.07 MPa versus 28.27 MPa at 28 days. Beyond 15%, strength decreased, with 35% FNS yielding only 22.06 MPa at 90 days (>30% reduction). The SAI confirmed SCM suitability at 5–10% FNS, meeting pozzolanic material thresholds with values of 99–102%. At these levels, pozzolanic contributions reached up to 11.23% at 7 days. UPV demonstrated strong correlations with compressive strength (R2 = 0.95) and density (R2 = 0.98), with the 10% FNS mix maintaining high matrix compactness (3928 m/s at 28 days). SEM images supported these results, showing refined pores and dense hydration products at 10% FNS, but porous, heterogeneous structures at 30%. LCA revealed that embodied energy reductions from 3751.01 MJ (control) to 2708.02 MJ (35% FNS), and GWP declines from 488.55 kgCO2-eq to 335.35 kgCO2-eq, indicating energy and emission savings of 27.78% and 31.39%, respectively. The sustainability index and economic index both identified 10% FNS as the optimum dosage, combining mechanical stability, minimized environmental impact, and the lowest cost-efficiency ratio of 3.46 $/m3/MPa. © 2026 Elsevier Ltd
Department of Civil Engineering, Faculty of Engineering, Universitas Hasanuddin, Gowa, South Sulawesi, 92171, Indonesia; Department of Civil Engineering, Faculty of Engineering, Universitas Negeri Padang, Sumatera Barat, Indonesia; Department of Civil Engineering, Faculty of Engineering, Universitas Andalas, Sumatera Barat, Indonesia; Department of Environmental Engineering, Faculty of Engineering, Universitas Hasanuddin, Gowa, South Sulawesi, 92171, Indonesia; Department of Civil Engineering, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Chiba-ken, Noda-shi, 278-8510, Japan
