Akademik Veri Yönetim Sistemi
14. ULUSLARARASI AZERBAYCAN FEN, MÜHENDİSLİK, MATEMATİK VE UYGULAMALI BİLİMLER KONGRESİ, Baku, Azerbaycan, 26 - 27 Mart 2026, ss.681-688, (Tam Metin Bildiri)
The effect of particle size fractions of Class C fly ash obtained from Kangal Thermal Power Plant on the 28-day compressive strength of geopolymer specimens activated with 12 M NaOH was investigated. Mixture composition was kept constant throughout the experimental program. Each specimen was prepared using 50 g of fly ash and 30 g of 12 M NaOH solution. The liquid-to-solid ratio, defined as the mass ratio of alkaline solution to fly ash, was maintained at 0.60. Fresh mixtures were cast with vibration, subjected to thermal curing at 70 °C for 24 h, and stored under ambient laboratory conditions until day 28. Raw fly ash was separated into six particle size fractions: +212, −212+106, −106+75, −75+53, −53+38, and −38 μm. Three specimens were produced for each fraction, and compressive strength was measured at 28 days (n = 3). Results showed that compressive strength increased with decreasing particle size up to a certain range, whereas strength decreased and data scatter became more pronounced in the finest fraction, −38 μm. The highest strength levels were obtained in the medium-fine fractions, with the −53+38 μm range showing the most favorable performance. The highest individual measurement, 16.40 MPa, was also recorded in that fraction; however, the relatively high scatter in the same range indicated that repeatability should be considered together with peak strength. The overall pattern suggests that increased fineness supports strength development up to a critical threshold by enhancing reactive surface area, whereas very fine fractions may activate limiting factors related to workability, compaction, and internal structural integrity under fixed mixture conditions.