Abstract
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.