Investigation of interlayer bond strength in concrete 3D printing technology

The advancement of concrete 3D printing in construction necessitates a thorough study of factors affecting interlayer adhesion, as it directly impacts the strength and durability of printed structures. The lack of sufficient data on the influence of mixture workability, aggregate type and ratio, and curing time limits the optimization of process parameters. Addressing these gaps will improve the quality of 3D-printed structures, expand their applications, and reduce defect risks. This study is crucial for the further development of additive manufacturing in construction, providing a scientific basis for refining printing methods. The aim of this work is to investigate the effects of fine-grained concrete mixture workability, sand fineness modulus, process interruption time, and curing duration on interlayer adhesion in additive construction. The results reveal key dependencies of interlayer bond strength on mix design and process factors: workability, sand fineness modulus, and curing duration under varying process interruptions. Optimal parameters for maximum interlayer bond strength in 3D-printed structures include a workability grade of Pk=3 and a sand fineness modulus of Mk=3. The observed effects are primarily attributed to chemical, diffusion, and adsorption adhesion mechanisms, with mechanical interlocking playing a secondary role. The findings indicate that the key approach to enhancing interlayer adhesion in additive construction lies in optimizing mixture composition, which governs hydration kinetics and material structure formation.