Experimental and multi-scale modelling investigation of printable, low-cement engineered cementitious composites with different Polyethene fibre contents

This study investigates the mechanical and environmental performance of 3D‑printable engineered cementitious composites (ECCs) with 1.0 %, 1.5 %, and 2.0 % polyethene (PE) fibres, targeting enhanced structural efficiency and sustainability. Fresh‑state rheological tests confirm that modest fibre inclusion increased yield stress and buildability, enabling stable printing of complex geometries, provided fibre clogging can be avoided. Hardened-state evaluation reveals pronounced strain-hardening and multiple micro-cracking in all mixtures, with ECC with 2.0 % fibres achieving the highest tensile strain (∼5.3 %) and compressive strength (∼71 MPa), while ECC with 1.5 % fibres offers the most balanced strength-ductility combination. Anisotropic elastic-plastic properties are characterised using Hill’s yield potential, and multi‑scale micromechanical modelling provides homogenised material parameters for the matrix-fibre system. Extended finite element (XFEM) simulations capture the dominant crack initiation, propagation paths and multi-crack evolution trends, providing mechanistic insight into fracture behaviour. A cradle‑to‑gate life‑cycle assessment reveals that PE fibre addition slightly increases global warming potential but improves strength‑normalised environmental efficiency, making ECCs with 1.5 % and 2.0 % fibres competitive with ordinary Portland cement concretes of similar strength. This integrated experimental-numerical framework demonstrates how optimised fibre dosages can enhance ductility, load capacity, and sustainability, offering a scalable approach for designing SCM-rich, low‑cement, high‑performance ECCs for thin‑walled and load‑bearing 3D‑printed structural components. • A multi-scale RVE-homogenisation-XFEM framework is developed for printed ECCs. • Hill’s anisotropic yield formulation captures print-induced directional behaviour. • The fibre content of 1.5 % provides the optimal strength-ductility performance. • The XFEM simulations reproduce crack branching and distributed micro-cracking. • The life cycle assessment links mechanical gains to reduced environmental impacts.