Mono-/poly-disperse nano-silica deposition for carbon textile-reinforced concrete: Microscale characterization

Abstract

Structural use of carbon textile-reinforced concrete (CTRC) remains challenging, primarily due to the lack of thermomechanical robustness at the textile/matrix interface. Nano-silica (NS) deposition has emerged as a viable solution to oft-employed polymer-based practices. However, its bond-enhancing mechanism is yet far from clear. This study presents results from a series of microscale characterizations to elucidate how the hydrodynamic properties of NS particles influence deposition characteristics and the interfacial bond. Results show that NS particles adsorb onto the roving surface more effectively with smaller mean particle size and higher polydispersity. The underlying mechanism is the adsorption-based interactions involving deposition-driving forces and interparticle attraction, which compete against desorption to immobilize the deposited particles. Such variations in deposition characteristics lead to polymorphism in the reticular network layer of secondary calcium silicate hydrate (C–S–H) phases. Its coverage level and topographical complexity both favor cohesive interconnection and microstructural densification in the roving/matrix interfacial transition zone (ITZ), playing crucial parts in improving mechanical properties. Correlation analysis indicates that a comprehensive interpretation from both chemical and physical aspects is key to unraveling the bond-enhancing mechanism of NS deposition.