Self-Healing 3D-Printed Concrete for Durable Automated Construction: A Simulated Crack- Recovery and Interlayer Performance Study

This empirical-style article presents a clearly labeled simulated study in Civil Engineering. A simulated 3D-concrete- printing study compared plain printable mortar, crystalline-admixture healing, microbial healing, and hybrid capsule-microbial healing. Layer interval, crack width, wet-dry exposure, compressive strength, interlayer bond, permeability recovery, and crack-closure ratio were modeled for 144 printed specimens. No real construction project or laboratory dataset was used. Hybrid healing produced the highest simulated crack-closure ratio for 0.30-mm cracks and the strongest permeability recovery, while crystalline healing provided a simpler performance-cost balance. Interlayer bond loss increased sharply when printing delay exceeded 20 minutes, indicating that healing technology does not eliminate the need for print-process control. The numerical observations, assignments, and measured outcomes are synthetic and intended for methodological illustration only. No real industrial facility, enterprise network, laboratory, construction project, or manufactured component was used. The study demonstrates a realistic research framework aligned with current 2026 research directions while clearly separating simulated evidence from verified literature.