Red mud utilization in fiber-reinforced 3D-printed concrete: Mechanical properties and environmental impact analysis

Abstract

3D printed concrete (3DPC) is an emerging technology that accelerates construction, minimizes material waste, and enhances design flexibility. However, the high environmental impact of cement remains a critical challenge. Red mud (RM) is an industrial by-product that presents a potential replacement for traditional cementitious materials, but its application in 3DPC has not been fully explored. This study addresses this gap by investigating the feasibility of using RM as a sustainable binder in 3DPC. The mechanical and environmental performance of 3DPC incorporating varying ratios of RM, fly ash (FA), and silica fume (SF) were conducted for evaluation. In this study, 3DPC mixtures containing RM were assessed by carrying out flowability, buildability, mechanical performance, digital image correlation (DIC), and X-ray computed tomography (X-CT) tests. The results demonstrated that incorporating 10 %wt RM achieved a compressive strength of 48.75 MPa and a flexural strength of 12.73 MPa, comparable to conventional cast mixtures. Besides, DIC analysis indicated that RM incorporated specimens exhibited a two-fold increase in mid-span deflection, indicating improved ductility. Additional, X-CT analysis revealed a reduction in porosity attributed to increased volcanic ash reactivity. In terms of sustainability analysis, RM effectively replaced a portion of cement in 3DPC, reducing Global Warming Potential (GWP) by up to 10 % and lowering Abiotic Depletion Potential (ADP) and Acidification Potential (AP). These results highlight the potential of RM to enhance the sustainability and mechanical performance of 3D printed construction materials, contributing to more environmentally friendly construction practices.