Abstract

To synergistically enhance the construction performance and durability of sulphoaluminate cement-based materials in cold regions, this study investigated the effects of cod antifreeze protein (AFP) on the workability and microstructural evolution of cement mortar. AFP was incorporated at dosages of 0%, 2%, and 4% by mass of cement, and the fluidity, consistency, setting time, and water absorption of the mortar were tested. Moreover, its action mechanism was analyzed combined with SEM-EDS, XRD, and amino acid composition analysis. The results showed that AFP could effectively improve the workability of cement mortar. Compared with the control group, the incorporation of AFP increased the mortar fluidity by 5.9%–7.1% and consistency by 64.3%–79.5%, and extended the initial setting time from 16.3 minutes to 42.7 minutes. Meanwhile, AFP reduced the water absorption of mortar by 0.31%–0.43% and significantly slowed down the water absorption rate. The results of microcharacterization indicated that the addition of AFP altered the morphology of hydration products and affected the formation and distribution of ettringite (AFt), thereby promoting the densification of the internal structure of the paste. Combined with amino acid composition analysis, it is suggested that the hydrophilic amino acids in AFP may improve the particle dispersion state and retard early hydration through interactions with ions and particle surfaces, while the hydrophobic amino acids may participate in the regulation of the internal structure of the paste. This study demonstrates that AFP has application potential in improving the workability and impermeability of sulphoaluminate cement mortar, and can provide a new insight for the performance optimization of cement-based materials in low-temperature environments.