Integration of Microwave Heating Device in Construction 3D Printing: A Novel Approach to Improve Sustainable Concretes Performance

Abstract

This thesis focuses on the design and development of a microwave irradiation device that can be integrated into a large-scale construction 3D printer. Moreover, the study also investigates the effects of this device in enhancing early-age compressive strength of sustainable construction materials. Finally, a comparison in microwave curing of an LC3 mixture with a conventional oven and the microwave irradiation device was also performed to find optimum conditions for the highest compressive strengths. For that purpose, a special 3D printable LC3-based mixture was prepared with local Kazakhstani materials. Compressive tests were conducted on early-age samples and further analyzed statistically using ANOVA to determine the optimal curing parameters within the given range. The designed microwave curing device was successfully developed, assembled, and experimentally tested. Statistical data demonstrates that microwave power and curing time have a statistically significant influence on early-age compressive strength. Further, a two-way ANOVA indicated that power and curing duration were statistically significant, suggesting potential ranges for these parameters that could improve performance. It is evident from the experimental results over the curing conditions used (600-800 W; 20-50 s) that the most effective curing condition was established as 800 W for 35 seconds and higher, which resulted in the greatest compressive strength of 2.678 MPa measured at 1 day. Similarly, on day 2, the greatest compressive strength of approximately 5.543 MPa was achieved at 800 W with a curing time of 50 seconds. Comparative test results showed that the microwave oven produced higher average compressive strengths for specimens prepared using the microwave heating device. Nevertheless, the developed device demonstrated a consistent improvement in strength and confirmed its feasibility for integration into 3D printing applications. The future of this study includes improvements in the microwave device's efficiency by optimizing the chamber design and how the energy from the microwave is distributed throughout the chamber, and by further refining the curing parameters to produce a high compressive strength and make it viable for use in additive manufacturing of cement-based materials.