Influence of NaOH molarity on the printability, mechanical performance, and environmental impact of calcium hydroxide- and micro-calcite-containing fly ash–GGBFS mortars for extrusion-based 3D printing
JOURNAL OF BUILDING ENGINEERING, cilt.133, ss.1-27, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 133
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.jobe.2026.117621
- Dergi Adı: JOURNAL OF BUILDING ENGINEERING
- Derginin Tarandığı İndeksler: Scopus, Science Citation Index Expanded (SCI-EXPANDED), Compendex, INSPEC
- Sayfa Sayıları: ss.1-27
- Erciyes Üniversitesi Adresli: Evet
Özet
This study investigates fly ash (FA)–GGBFS-based alkali-activated mortars containing calcium hydroxide (CH) and micro-calcite filler (MCF) for extrusion-based 3D printing, focusing on the influence of NaOH molarity on printing, mechanical, microstructural, and environmental performance. Nine mortar mixtures were initially evaluated in terms of flowability, setting time, extrudability, buildability, vane shear resistance, and flexural and compressive strengths. Based on this multi-criteria assessment, MS-4 and MS-5 were selected as the most suitable formulations. Both exhibited a flow diameter of 155 mm, while initial setting times were 110 and 90 min and vane shear resistance values were 22 and 23 kPa, respectively. Controlled rheological tests showed that CH modified yield stress, plastic viscosity, and structural build-up behavior. Both selected mortars exhibited continuous extrusion and stable deposition, with MS-5 enabling printing of up to 11 layers without significant deformation. At 28 days, compressive strengths in the X, Z, and Y directions increased from 28.52, 16.94, and 11.43 MPa for MS-4 to 30.69, 22.86, and 14.54 MPa for MS-5, confirming printing-induced anisotropy. MS-5 also exhibited a denser and more homogeneous microstructure. The alkali-activated mortars showed lower environmental impacts than Portland cement mortar in most categories, although NaOH remained the dominant contributor.