Akademik Veri Yönetim Sistemi
Journal of Building Engineering, cilt.111, 2025 (SCI-Expanded, Scopus)
The increasing environmental burden of Portland cement production has accelerated the search for sustainable alternatives in construction materials. This study investigates the development and optimization of high-performance alkali-activated composites (AACs) using industrial and agricultural waste products as binders and aggregates. Ground granulated blast furnace slag (GBFS) was used as the primary precursor, partially replaced by 15 % waste brick powder (BP), natural zeolite (NZ), or rice husk ash (RHA) as supplementary cementitious materials (SCMs), while 100 % waste marble powder (WMP) was employed as fine aggregate. The aim was to assess the mechanical, durability, and microstructural properties of these eco-efficient AACs under varying sodium silicate-to-sodium hydroxide (NS/NH) ratios (1.5–3.0) and thermal curing conditions (40 °C and 80 °C), and to identify the optimal formulation for high-performance applications. The key innovation of this study lies in the complete elimination of cement and natural sand, replaced by four different waste materials, with comprehensive evaluation across multiple performance criteria. The highest compressive strengths were recorded at an NS/NH ratio of 2.5 and 80 °C, reaching 44.58 MPa (BP), 43.54 MPa (NZ), and 44.02 MPa (RHA). Similarly, the maximum flexural strengths were 5.63 MPa (BP), 5.54 MPa (NZ), and 5.43 MPa (RHA) under the same conditions. The lowest compressive strengths were obtained at an NS/NH ratio of 1.5. The highest oven-dry densities were obtained at NS/NH = 2.5 and 80 °C, ranging between 2111 and 2149 kg/m3. The lowest porosity was recorded as 6.40 % for RHA-based mixtures under the same conditions. The lowest sorptivity was 0.59 kg/m2 for BP-based composites cured at 80 °C and NS/NH = 2.5, while the highest sorptivity values were observed at NS/NH = 1.5 across all precursor types. After exposure to 600 °C, strength losses ranged from 33.5 % to 78.4 %, with NZ-based mixtures showing the best thermal resistance. Under sulfate attack, strength losses varied between 11.1 % and 37.0 %, with RHA- and BP-based mixtures performing better than NZ-based ones. Freeze–thaw cycles caused strength losses between 6.8 % and 38.4 %, with NZ- and BP-based mixtures showing improved durability depending on curing and activator ratio. This work demonstrates a holistic approach toward circular economy goals, offering a viable pathway for producing durable, low-carbon, high-performance composites suitable for structural applications.