Investigation of the High Temperature Resistance of Foam Concrete Produced with Dıfferent Cem-II Type Cements

In this study, three foam concrete mixtures—each utilizing pumice aggregate and fixed foam/water content (240–50–220 g/dm³) but differing in binder type (PKB-I: CEM II/A-M (S–L); PKB-2: CEM II/A-S; PKB-3: CEM II/A-LL)—were comprehensively examined in terms of their fresh and hardened properties, permeability indicators, and high-temperature behavior. The mixtures were produced with constant mix ratios, and parameters such as density (fresh/hardened), total water absorption, open porosity, ultrasonic pulse velocity (UPV), and compressive strength at 3, 7, and 28 days were determined. For high-temperature evaluation, the specimens were exposed to 200, 400, 600, and 800 °C, and the corresponding mass loss and strength variation (%) were calculated. The results indicated that early-age mechanical development was strongly influenced by binder chemistry, with strength ranking at day 3 following the order PKB-2 > PKB-3 > PKB-I; by day 7, these differences had narrowed, and by day 28, all three systems converged to approximately 10.5–10.8 MPa. Although PKB-2 exhibited the highest unit weight, it also demonstrated the greatest porosity and water absorption. Ultrasonic pulse velocity showed a positive correlation with density and a negative correlation with porosity within the same density range. As temperature increased, mass loss gradually rose, converging at around 18–20% at 800 °C. Limited strength gains were observed between 200 °C and 400 °C due to internal water redistribution and gel relaxation, while all mixtures exhibited significant strength reductions at ≥600 °C; the limestone-based system (PKB-3) showed more pronounced losses associated with CaCO₃ decomposition. Overall, CEM II/A-LL proved suitable for lightweight elements requiring low water absorption, CEM II/A-S for applications prioritizing early-age strength, and CEM II/A-M (S–L) provided a balanced design window between mechanical, transport, and thermal stability.