Engineering one‐part geopolymer for 3D printing using dolomite powder: Rheology, printability, microstructure and sustainability

Abstract The widespread adoption of one‐part geopolymer cementitious composites for additive manufacturing is constrained by the declining availability of conventional precursors such as fly ash and the limited understanding of alternative calcium‐rich materials that can simultaneously satisfy the rheological and mechanical requirements of concrete 3D printing. Although dolomite powder is abundantly available as an industrial by‐product, its potential as a precursor for one‐part geopolymer cementitious composites designed for 3D printing remains largely unexplored. This study systematically investigates the influence of dolomite powder as a partial replacement for fly ash on the fresh, rheological, mechanical, microstructural, and environmental performance of one‐part geopolymer cementitious composites for extrusion‐based 3D printing. Four geopolymer mixtures containing 0%, 10%, 30%, and 50% dolomite powder replacement of fly ash were evaluated in terms of flowability, setting time, printability, rheological behavior, anisotropic compressive strength, density, reaction kinetics, pore structure, and microstructural development. The results demonstrate that the incorporation of 30% dolomite powder provides the optimum balance between fresh and hardened performance by enhancing static yield stress, apparent viscosity, buildability, and printability while maintaining satisfactory mechanical properties. In contrast, replacing 50% of fly ash with dolomite powder accelerated reaction kinetics and improved hardened properties but significantly reduced workability and printability owing to excessive stiffness and rapid structural build‐up. Microstructural characterization using isothermal calorimetry, XRD, FTIR, TGA/DTG, MIP, and FESEM‐EDS confirmed that the improved performance resulted from accelerated geopolymerization, refined pore structure, and the formation of a denser reaction matrix. The proposed dolomite‐based one‐part geopolymer cementitious composite achieved an estimated reduction in embodied carbon and embodied energy of 18%–62% compared with conventional OPC‐based concrete, demonstrating its potential as a sustainable material for digital construction. This study provides new insights into the role of dolomite powder in tailoring the rheology, printability, and performance of one‐part geopolymer cementitious composites and establishes practical guidance for the development of low‐carbon materials for large‐scale concrete 3D printing.