Recycled Plastic in 3D‐Printed Cementitious Concrete: Current Status and Research Gaps

Plastic waste (PW) leads to a considerable environmental challenge, highlighting the need for effective recycling strategies. One promising approach is its incorporation into emerging advanced technologies, such as extrusion‐based cementitious 3D‐printed concrete (3DPC), which can enhance material efficiency while reducing plastic disposal. This paper presents a concise review of recent studies on the incorporation of PW into cementitious 3DPC. Parameters such as the type of PW and particle characteristics, including length, width, or diameter, and their effects on 3DPC properties are critically analyzed. Any surface modification techniques applied to PW are discussed, and maximum and suitable replacement levels of PW are also documented. Incorporating PW aggregates in 3DPC mixes usually enhances the flowability but tends to negatively affect buildability, compressive strength, flexural strength, and interlayer bond strength. The optimum PW aggregate replacement level appears to be ∼5% of the total mix volume or ∼10% of the sand volume. Conversely, using PW fibers lowers flowability while improving buildability and overall mechanical performance. The optimum PW fiber dosage is ∼0.3% of the cementitious materials by weight or 0.3%–1% of the total mix volume, depending on fiber type and dimensions. The review also discusses the influence of PW on durability, sustainability, and cost. Incorporating PW into 3DPC offers a sustainable approach that reduces environmental impact, conserves natural resources, and links waste management with advanced construction technologies, promoting a greener environment. Finally, this review provides a foundational reference for the preliminary optimization of PW in 3DPC and for directing future research.