A study on nanosilica- and microsilica-added concretes under different transport mechanisms

This paper presents the relative performance of nanosilica (nS)- and microsilica (mS)-added concrete with reference to durability under different transport mechanisms such as absorption, sorption, diffusion and migration. The concrete for this study was made with optimum quantities of mS and nS, which were determined based on maximum strength efficiency factor. The results showed that nS-added concrete exhibited superior durability properties compared to mS-added concrete under the above transport mechanisms, even at lower cement replacement. The beneficial effects of nS on the pore refinement of concrete were observed through the latter's high resistance to water absorption, sorptivity, chloride penetration and corrosion susceptibility. The relatively higher rapid chloride permeability and lower concrete resistivity of nS added concrete were attributed to the possible static surface charge of nS particles. The scanning electron microscopic image showed a compact and dense microstructure of nS-added concrete with increased finer-sized calcium–silicate–hydrate, reduced calcium hydroxide contents, and compact interfacial transitional zones.