The impact of fiber types on the mechanical and microstructural properties of one-part alkali-activated mortars after sequential freeze-thaw and elevated temperatures exposure
JOURNAL OF BUILDING ENGINEERING, cilt.132, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 132
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.jobe.2026.117534
- Dergi Adı: JOURNAL OF BUILDING ENGINEERING
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC
- Karadeniz Teknik Üniversitesi Adresli: Evet
Özet
One-part alkali-activated mortars (OPAAMs) have attracted increasing attention as alternative binders because of their environmental benefits and favorable mechanical performance. However, information regarding the performance of these materials is limited, particularly in situations where environmental effects occur sequentially. In particular, the effect of prior freeze-thaw (F-T) damage on the subsequent high-temperature resistance of these materials has not been sufficiently elucidated. Therefore, the primary objective of this study is to determine how preexisting F-T damage affects the subsequent high-temperature performance of OPAAMs and to evaluate the effectiveness of different fiber types and fiber contents in mitigating this sequential damage. To this end, glass (G), basalt (B), polypropylene (PP) and carbon (C) fibers were added to the mixtures at volume fractions of 0.5% and 1.0%. After being subjected to 125 F-T cycles, the specimens were heated to temperatures of 400 degrees C and 800 degrees C, and their mechanical, phase and microstructural properties were evaluated. The results showed that F-T pre-damage had a clear effect on the subsequent response to elevated temperatures, and this effect depended on fiber type. Fiber addition generally improved strength and toughness by reducing brittle behavior, particularly in flexure. The highest mechanical performance was obtained with C fibers. Increasing the fiber content from 0.5% to 1.0% further improved strength and energy absorption, especially in C- and B-fiber mixtures. In contrast, PP-fiber mixtures showed lower compressive and flexural strengths due to increased porosity. All mixtures deteriorated after 400 degrees C, with greater losses at 800 degrees C. However, mixtures with 1.0% C fiber retained the highest residual compressive and flexural strengths. Mass loss was limited after F-T but increased significantly at elevated temperatures due to water loss, dehydroxylation, and decarbonation. XRD and FTIR results indicated gel decomposition and reduced polymerization with increasing temperature. FESEM-EDS showed complete decomposition of PP fibers, while G and B fibers remained relatively stable. C fibers provided the most effective reinforcement due to their high thermal stability. The results show that F-T pre-damage plays an important role in the subsequent thermal performance of fiber-reinforced OPAAMs.