Performance buildup of concrete cured under low-temperatures: Use of a new nanocomposite accelerator and its application

Abstract

Although revealed with some benefits, the use of traditional accelerators in concrete indeed encounter some issues such as the deterioration of concrete durability. Therefore, this study proposed a new nanocomposite accelerator (NCA), whose influences on the fresh (e.g., workability) and hardened properties (e.g., strength and durability) of C60 high-strength concrete (HSC) under low temperature curing (i.e., 16 °C and 6 °C) were studied. The experimental results revealed that although low curing temperatures damage the overall fresh and hardened performances of concrete, their performances were compensated via the use of the proposed NCA. The slump and slump flow were increased and the workability loss over time was reduced. The setting time was significantly shortened whereas negligible effects were revealed by NCA on the air content of fresh concrete. The addition of NCA significantly enhanced the compressive strength of HSC under low-temperature curing, especially in an early age (i.e., 3 days). The HSC with NCA could reach the standard of impermeable concrete, and no visible cracks were found in the annular crack resistance test. It belonged to low-permeability concrete and could be applied to extreme chloride ion environments. The content of chloride ion and alkali also met the design specifications. The enhanced workability, strength development and durability of concretes with NCA enabled the overall indicators of the high strength concretes to meet the corresponding requirements even when they were cured in low-temperatures.