Canaries nest-inspired assembly of organic-inorganic networks for shotcrete: A rapid setting and hardening strategy via biomimetic design

Shotcrete is a critical lining material for tunnel constructions. However, previous studies have struggled to simultaneously achieve excellent workability, rapid-setting, high early-strength and superior toughness. Inspired by nest-building behavior of canaries, this study integrates in-situ polymerization with the alkali-free accelerator (AC) to rapidly construct an organic–inorganic skeleton and optimize early-age performance. The results indicated that in-situ polymerization improved the workability of the mortar within 1 h. Hydration kinetic analysis demonstrated that AC promoted ettringite formation and released heat, triggering monomer polymerization. The polymerization process further enhanced cement hydration, generating a mutual activation effect. This synergy reduced the percolation threshold, significantly shortening the setting time. The accelerated hydration subsequently produced “mud-like” hydration products that filled the pore structure, resulting in a denser matrix. Consequently, the 6 h compressive strength reached 2.7 MPa, representing an 800 % increase compared with the Con, and the flexural strength exhibited remarkable improvements of 400 %, 84 %, and 22 % after 6 h, 1 d and 28 d of hydration, respectively. This study provides a novel strategy for designing high-performance shotcrete and promoting the high-quality development of tunnel constructions.