Development direction of early strength properties of calcium formate in concrete admixture

The raw materials of the concrete are abundant, the price is low, and the characteristics of the simple production process are increasing. Used in actual projects, the admixture has played an important role in improving concrete performance, improving construction efficiency and saving investment costs. Calcium formate early strength agent is one of them. Next, we mainly explain the development direction of some calcium formate early strength agents.

Concrete early strength agent is one of the earliest used additives in the history of admixture development. So far, people have developed a variety of early strength additives in addition to chloride and sulfate, such as nitrite, chromate, etc., and organic early strength agents, such as calcium formate, urea, etc.

However, with the deepening of people's understanding of the potential hazards of chloride ions, sulfate ions, nitrate ions and alkali metal ions on the performance and long-term stability of concrete, as well as the development of large-volume slag powder or fly ash concrete, formic acid Calcium is used more in actual projects.

The development direction of calcium formate early strength agent:

(1) Vigorously develop the production and application of calcium formate early strength agent. Greatly increase the early strength development rate of concrete; it can not only improve the early strength of concrete, but also bring benefits to the later strength development of concrete.

(2) Incorporated into cement stick concrete, it acts as a catalyst in the cement hydration process, it can accelerate the hydration of C3A and the formation of ettringite, and the early strength effect is better. The formic acid in the calcium formate early strength agent is a weak acid, and there is a process of hydrolysis in the aqueous solution. Therefore, the aqueous solution of calcium formate should be weakly alkaline, which can not only play a good early strength effect, but also prevent some early strength components from causing corrosion of steel reinforcement in the concrete.

(3) Incorporating calcium formate early strength agent changes the sulfate resistance of concrete. It is suitable for pumping and non-pumping construction of ordinary concrete and prestressed reinforced concrete. It has good applicability to ordinary portland cement and slag portland cement.

(4) Carrying out the research on the adaptability of calcium formate early strength agent to cement/admixture to choose the early strength agent more scientifically and receive better and more economical application effects.

Concrete early strength agents are mostly inorganic salts, and when the amount is large, it is detrimental to the later strength of the concrete. Chloride early strength agent can cause steel bar corrosion. Sulfate early strength agent may produce volume expansion, which reduces the durability of concrete. Sodium early strength agent will increase the alkali content of concrete and increase the risk of alkali-aggregate reaction. In fact, modern industrial development of calcium formate early strength agent has been used in large quantities in actual projects. It has played an important role in improving concrete performance, improving construction efficiency and saving investment costs.