MECHANICAL PERFORMANCE AND PRINTABILITY FACTORS IN 3D PRINTED CONCRETE: A SYSTEMATIC REVIEW OF MIX DESIGN, PROCESS PARAMETERS, AND CURING CONDITIONS

Abstract

Additive manufacturing with concrete is rapidly transforming the construction industry, yet the interplay between material formulations, processing conditions, and final mechanical performance remains a complex challenge. This systematic review aims to synthesize the vast body of research on the mechanical performance and printability of 3D-printed concrete, focusing explicitly on how mix design, process parameters, and curing conditions collectively govern outcomes. We systematically identified and analyzed the relevant literature through a structured approach, extracting data on fresh-state rheology, hardened mechanical properties, and interlayer bond strength. Our analysis reveals that the optimization of mix design is centered on the balance between flowability and buildability, with supplementary cementitious materials and chemical admixtures playing critical roles. Furthermore, process parameters such as printing speed and nozzle geometry were found to directly control the extrudate shape and layer adhesion, thereby influencing anisotropy and structural integrity. The results also demonstrate that curing conditions—particularly early-age moisture retention—substantially impact strength development and durability. We conclude that a holistic framework, which integrates the optimization of sustainable material recipes with the precise tuning of printing protocols and post-deposition curing, is necessary to achieve both reliable printability and superior mechanical properties. This review therefore provides a consolidated knowledge base that can guide researchers and practitioners toward developing more robust and sustainable 3D-printed concrete structures.