A Brief Review on Materials and Printing Processes Employed in 3D Fiber Reinforced Concrete for Environmental Sustainability

3D-printed concrete, a transformative technology in the construction field offering design, flexibility, labor efficiency, allows complex shapes and is more sustainable as it reduces material waste, minimizes formwork, architectural freedom, and energy consumption compared to conventional concrete. Conventional concrete is strong and reliable but completely depends on formwork which requires more labor and results in material waste and carbon emissions. It posses higher compressive strength but lower tensile strength which will be overcome by introducing fibers and the product will emerge as Fiber Reinforced Concrete (FRC). Several reviews were conducted on 3D Fiber Reinforced Concrete (3DFRC) and among those extrusion-based printing technique, binder jetting and spray-based techniques were employed. However, extrusion-based printing technique was significant. Several researchers continued their studies using wide range of fibers like steel, carbon etc., which can provide significant gains in strength and ductility and their impacts on printability, mechanical and durability properties. But basalt fibers offer superior durability in marine environments. The use of supplementary cementitious materials (SCMs) such as recycled aggregates, waste materials like fly-ash, GGBS, Rice husk ash can cause environmental sustainability by reducing higher quantity of cement for minimizing carbon emissions. Some studies related to Life cycle assessments (LCAs) for potential environmental benefits were also carried out.. Absence of conventional reinforcement in printed elements pose structural challenges in tensile and flexural capacities. To mitigate limitations and to enhance characteristics viz., ductility, crack control, and post-crack toughness the technique of fiber reinforcement has become a remarkable strategy. In the present scenario, fibers from synthetic to high-performance materials like basalt and Carbon, plant-based and recycled fibers are being used as fillers in 3D concretes. The present review clearly explains the advancements made in (3DFRC) and the interplay between printing methods, fiber types, and environmental sustainability. Fiber-matrix interfaces, development of multi-scale reinforcement strategies, and establishment of design guidelines for structural 3DFRC elements need to be prioritized for future directions in this field.