Synergistic influence of metakaolin and carbon fibers on the physical, thermal, and residual mechanical performance of pumice-based lightweight mortars before and after high-temperature exposure
Structures, cilt.90, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 90
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.istruc.2026.112357
- Dergi Adı: Structures
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Anahtar Kelimeler: Carbon fibers, Flexural toughness, High-temperature effect, Lightweight concrete, Metakaolin, Residual strength
- Van Yüzüncü Yıl Üniversitesi Adresli: Evet
Özet
Lightweight concrete (LWC) improves thermal insulation and reduces structural self-weight, thereby decreasing seismic loads. However, Portland cement (PC), the primary binder in LWC, contributes significantly to CO₂ emissions. In this study, 20% of PC was replaced with metakaolin (MK) to improve sustainability, while carbon (CA) fibers with lengths of 3, 6, and 12 mm were incorporated to enhance toughness and high-temperature performance. The combined effects of MK and CA fibers on the fresh, physical, thermal, and mechanical properties of pumice-based lightweight mortars were investigated under ambient conditions and after exposure to 300, 600, and 900 °C. The evaluated properties included flow diameter (FD), water absorption (WA), thermal conductivity (K), compressive strength (CS), flexural strength (FS), flexural toughness (FT), mass loss (ML), residual compressive strength (RCS), and residual flexural strength (RFS). All mixtures were produced using 0–2 mm pumice aggregate, and CA fibers were applied in both single- and multi-length configurations. The results indicated that MK reduced workability and WA due to its high fineness and filler effect while improving CS and FS through matrix densification and secondary hydration reactions. CA fibers significantly enhanced toughness behavior through crack-bridging mechanisms, delaying crack propagation and increasing energy absorption capacity. Mixtures containing combined long and short CA fibers exhibited superior toughness and improved residual mechanical performance after high-temperature exposure.