Customarily, retarders serve as the setting time regulators of cement-based composites to meet the demands of various construction environments. However, the limited ability to adjust the setting time restricts the application of polysaccharides in special environments. In this study, we reported a naturally high-efficiency retarder, konjac glucomannan (KGM), and studied the mechanism of its effect on the hydration of ordinary Portland cement. Incorporating KGM could significantly prolong cement hydration without strength damage. Furthermore, the active hydroxyl group (−OH, rich in KGM) could chelate with Ca²⁺ (released from cement hydration) to form a cross-linking network, which is adsorbed on the surface of cement clinker, thereby being conducive to delaying the process of cement hydration and reducing the heat of hydration. The findings of this study are critical to the ongoing efforts to develop polysaccharide-cement-based composite materials for application in various special environments.

The penetration of external stimuli (microorganisms, ions, etc.) following to the pore is the key reason for the deterioration of cement and concrete structures. Although the traditional methods such as improving the chemical composition of cement and concrete materials can delay the erosion rate, the inevitable pore structure still makes its deterioration a challenge. Based on this, we reported a protective coating for cementitious materials based on phenol and Ti₃C₂ MXene-modified polyacrylate (MXene-PG/PA). The introduction of phenols enhanced the waterproof properties of polyacrylate by increasing the interaction among molecular chains. Moreover, the introduction of Ti₃C₂ MXene also endows the MXene-PG/PA coating with good light-induced antimicrobial properties. Beneficial to these designs, the MXene-PG/PA coating exhibited good waterproof properties (the water absorption ratio in seawater decreased by 58.2%) and antimicrobial properties (inhibition of E. coli and S. epidermidis activity under light). These results not only confirm that the MXene-PG/PA coating is a potential candidate of protective coating for cement-based materials, but also provide a new strategy for the design of multifunctional protective coatings.