Effect of a Nitrite/Nitrate-Based Accelerator on the Strength Development and Hydrate Formation in Cold-Weather Cementitious Materials.

Recently, there has been increased use of calcium-nitrite and calcium-nitrate as the main components of chloride- and alkali-free anti-freezing agents to promote concrete hydration in cold weather concreting. As the amount of nitrite/nitrate-based accelerators increases, the hydration of tricalcium aluminate (CA phase) and tricalcium silicate (CS phase) in cement is accelerated, thereby improving the early strength of cement and effectively preventing initial frost damage. Nitrite/nitrate-based accelerators are used in larger amounts than usual in low temperature areas below -10 °C.

Evaluation of Mechanical and Shrinkage Behavior of Lowered Temperatures Cementitious Mortars Mixed with Nitrite-Nitrate Based Accelerator.

Recently, calcium nitrite (Ca(NO)) and calcium nitrate (Ca(NO)) have been increasingly used as the main components of salt- and alkali-free anti-freezing agents, for promoting concrete hydration in cold-weather concreting. With an increase in the amount of nitrite-based accelerator, the hydration of CA, CS, and βCS in the cement is accelerated, thereby improving its early strength and effectively preventing the initial frost damage. Meanwhile, with an increase in the amount of nitrite-based accelerator, the expansion and shrinkage of the concrete-and, therefore, the crack occurrence-are expected to increase.

Physicochemical Study on the Strength Development Characteristics of Cold Weather Concrete Using a Nitrite-Nitrate Based Accelerator.

There has recently been an increased use of anti-freezing agents that are primarily composed of salt- and alkali-free calcium nitrite (Ca(NO)) and calcium nitrate (Ca(NO)) to promote the hydration reaction of concrete in cold weather concreting. Nitrite-nitrate based accelerators accelerate the hydration of CA and CS in cement more quickly when their quantities are increased, thereby boosting the concrete's early strength and effectively preventing early frost damage. However, the connection between the hydrate formation behavior and the strength development characteristic over time has yet to be clearly identified.