Electrochemical C-S-H deposition for enhancing hydrophobic PP fiber/cement interface: Experimental and DFT-MD insights

The poor interfacial adhesion between hydrophobic polypropylene fiber and cementitious matrix, stemming from the fiber’s inert surface and low wettability, limits the strength of fiber-reinforced cement composites. This study proposes an electrochemically driven C-S-H coating strategy that enables in-situ deposition of cement-compatible phases on the fiber surface. The modified fibers exhibit reduced contact angle and improved work of adhesion, resulting in 81.8% higher interfacial shear strength and 161.8% greater pull-out energy compared with unmodified composites. The enhanced interfacial performance is attributed to H-bond interactions, improved wettability, and the formation of a chemically compatible C-S-H interface. DFT and MD simulations provide the molecular-level insights, suggesting that the applied electric field amplifies the fiber’s negative electrostatic potential and enhances Ca 2+ adsorption and ion/fiber interactions. The electrochemical surface modification strategy, which introduces chemically compatible phases without additive binders or harsh chemicals, offers a scalable, sustainable approach to improve interfacial bonding in hydrophobic fiber/cement composites.