Ambient-Cured One-Part Fly Ash–GGBS Geopolymer Mortar for Extrusion-Based Three-Dimensional Concrete Printing: Sequential Engineering and Microstructural Optimization

Maulik Mistry; Hardik Solanki; Ravindra Gupta

doi:10.30564/jbms.v8i3.13722

Authors

Maulik Mistry
Faculty of Engineering and Technology, Parul University, Waghodia, Vadodara 391760, Gujarat, India
Hardik Solanki
Department of Civil Engineering, Parul Institute of Engineering and Technology, Faculty of Engineering and Technology, Parul University, Waghodia, Vadodara 391760, Gujarat, India
Ravindra Gupta
Department of Automobile Engineering, Parul Institute of Engineering and Technology, Faculty of Engineering and Technology, Parul University, Waghodia, Vadodara 391760, Gujarat, India

DOI:

https://doi.org/10.30564/jbms.v8i3.13722

Received: 1 July 2026 | Revised: 21 July 2026 | Accepted: 7 August 2026 | Published Online: 4 September 2026

Abstract

The formulation of one-part geopolymer mortars for extrusion-based three-dimensional concrete printing (3DCP) requires a balance between fresh-state workability, controlled setting behaviour, and adequate mechanical strength. To address this need, this study established a sequential mixture-selection framework for ambient-cured, one-part fly ash–ground granulated blast-furnace slag (FA–GGBS) geopolymer mortar and evaluated its fresh-state behaviour, setting characteristics, compressive strength, and microstructure. Increasing the GGBS content reduced the workability retention and setting time while substantially increasing the compressive strength. Similarly, increasing the sodium metasilicate dosage from 10 to 15 wt.% further accelerated setting but shortened the available working period. The FA50G50 binder, which contained 10 wt.% sodium metasilicate, provided the most favourable balance between workability retention and controlled hardening, with initial and final setting times of 80 and 115 min, respectively. An aggregate-to-binder (A/B) ratio of 1.50 produced the best hardened performance, and the selected FA50G50-A10-AB 1.50 mixture achieved compressive strengths of 46.5 and 63.2 MPa at 7 and 28 days, respectively. Microstructural analysis emphasized a dense, continuous, mainly amorphous aluminosilicate reaction matrix with a calcium-containing product. This study integrated fresh-state, setting, mechanical, and microstructural criteria into a sequential mixture-selection approach rather than selecting the composition primarily based on compressive strength. The final optimized mixture provides a basis for future rheological characterization and extrusion-based 3DCP investigations; however, its direct printability was not experimentally validated.

Keywords:

One-Part Geopolymer; Fly Ash–GGBS; Sequential Mixture Selection; Ambient Curing; 3D Concrete Printing

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