Highly efficient resistance to chloride ion penetration and enhanced compressive strength in cement coupled with cationic polymer grafted nano-silica

Abstract

The degradation and loss of structural integrity in concrete due to chloride ion-induced corrosion of steel reinforcement represent significant challenges that limit the service life of concrete structures. To combat this, cationic polymer (polydimethylaminoethyl methacrylate quaternary ammonium, PDEMAQA) grafted nano-silica (SiO₂-g-PDEMAQA) was prepared by atom-transfer radical-polymerization (ATRP) reaction to enhance the chloride ion penetration resistance of cement. On one hand, cationic polymer provides the ability to facilitate the dispersion of nano-SiO₂ within cement, thereby promoting cement hydration. On the other hand, the substantial presence of quaternary amine groups in cationic polymer enhances the capacity to effectively bind free chloride ions in cement. Consequently, the incorporation of a modest quantity of organic polymer-modified nano-silica could lead to marked improvements in both the resistance to chloride ion penetration and the compressive strength of cement. The experimental results demonstrate that cement doped with just 1.0 wt% SiO₂-g-PDEMAQA could not only significantly improve early resistance to chloride ion penetration by 66.91 %, but also increase the compressive strength by 9.79 % after 28 days of curing. Benefiting from the synergistic effect of cationic polymer and nano-SiO₂, SiO₂-g-PDEMAQA exhibits highly efficient chloride ion penetration resistance and enhanced compressive strength. This work will develop a strategy of improving resistance to chloride corrosion in cement with high efficiency, and will contribute to the sustainable advancement of concrete technology.