Admixtures are used in concrete to speed up the setting time. They also increase the early strength of the concrete. These additives can be added before or during the mixing process. Some of them are made from chemical or mineral sources, while others are added at the factory.
One of the most common accelerators is calcium chloride. Calcium chloride is available in pellets and flakes. You can purchase it from most local hardware stores. In addition to its effect in speeding up the setting time of concrete, calcium chloride can also improve the workability of the mix.
Alternatively, you can add a water-reducing admixture. Water-reducing admixtures can provide more fluidity to the concrete and can be useful for slipform construction or for long-distance transportation. Another option is to use a corrosion inhibitor. It can be effective in marine environments and in bridges and parking structures. However, this effect does not have a great impact on the strength of the concrete.
Other accelerating admixtures include sodium thiocyanate, triethanolamine, and calcium formate. Each of these admixtures can be used in combination with other admixtures, depending on the concrete’s application.
The final set time of the concrete is determined by the amount of accelerator added, the temperature of the water, and the dosage rate. Conventional set retarders, on the other hand, slow down the hydration process, making the concrete harder. Although they can be effective, conventional set retarders tend to wear off quickly.