Near‐Nozzle Mixing for Additive Manufacturing of Cementitious Mortar: A Homogeneity Study

This paper investigates the Near‐nozzle Mixing (NNM) technique for 3D printing cementitious mortar, focusing on achieving continuous and homogeneous material properties. The NNM's ability to print Natural Sand Mortar (NSM), Recycled Aggregate Mortar (RAM), and Lightweight Mortar (LWM) was assessed. Fresh and hardened properties of each mortar were examined, emphasizing standard deviation (STD) and coefficient of variation (CV) to measure material homogeneity. Fresh properties included slump flow, yield stress, air void volume, density, and water‐to‐cement ratio, while hardened properties covered compressive strength, flexural strength, hardened density, and thermal conductivity. Results showed low CV values for all mortar types, indicating high consistency and homogeneity. NNM showed is capability to print of various materials with customized properties. NSM showed the highest compressive strength, RAM balanced strength and sustainability, and LWM provided the best thermal insulation. The study highlights NNM's versatility and potential for construction applications requiring tailored properties, proving it a promising additive manufacturing solution. The research serves as a foundation for future studies on graded multi‐material printing.