Sustainability Assessment of Three-Dimensional Printed Geopolymer Concrete: An Integrated Environmental and Economic Evaluation Framework

The construction sector contributes 39% of global carbon emissions, with traditional cement production accounting for 8% of total CO₂. This research presents an integrated assessment framework combining Life Cycle Assessment (LCA) and Multi-Criteria Decision Analysis (MCDA) to evaluate sustainability performance of three-dimensional printed geopolymer concrete (3DP-GPC). Using industrial by-products (fly ash and ground granulated blast furnace slag) as binders, geopolymer formulations achieved 40-80% embodied carbon reduction compared to Ordinary Portland Cement. An experimental program evaluated three geopolymer mixtures and one conventional control across technical (strength, printability, durability), environmental (carbon footprint, energy demand, waste), economic (material and lifecycle costs), and social (safety, acceptance, employment) dimensions. Life cycle inventory data followed ISO 14040/44 standards, incorporating production, transportation, manufacturing, construction, and end-of-life phases. The Analytical Hierarchy Process (AHP) established criterion weights through expert elicitation; Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) ranked alternatives. Results demonstrated that a balanced formulation (50% fly ash/50% slag) achieved 55.8% carbon reduction, target compressive strength (52 MPa), superior durability characteristics, and 9% lifecycle cost savings despite 28% material cost premium. Sensitivity analysis confirmed robust performance across diverse weighting scenarios. Extension to cradle-to-grave boundaries, accounting for durability advantages, increased environmental benefit to 58.6%. This research establishes a replicable, transparent decision-support framework enabling industry adoption of low-carbon construction technologies while acknowledging explicit trade-offs inherent in material selection decisions.