A. M. Yasien, M. T. Bassuoni, A. Abayou, and A. Ghazy



With aging, concrete structures exhibit deterioration due to multiple reasons. Consequently, repair processes become overwhelmingly essential to extend the service life of structures.

This experimental study investigated nano-modified concrete cast and cured under cyclic freezing/low temperatures, including its applicability to partial-depth repair. Seven mixtures, incorporating general-use cement, fly ash (0 to 25%), and nanosilica (0 to 4%) with a cold weather admixture system (antifreeze/accelerator) were tested.

The mixtures were evaluated based on fresh, hardened, and durability properties as well as their compatibility with parent/substrate concrete. In addition, mercury intrusion porosimetry and thermogravimetric analysis were conducted to assess the evolution of microstructure under cold temperatures.

The incorporation of 4% nanosilica in the cementitious binder, even with the presence of 15% fly ash, markedly enhanced the performance of concrete cast and cured under low temperatures without protection; thus, it may present a viable option for cold weather applications including repair.