Action Principle of Concrete Admixture

Action Principle of Concrete Admixture

Concrete additives, called admixtures for short, are substances used to improve the performance of concrete. As a common additive in construction engineering, concrete admixture has become essential in construction engineering. It directly affects the structural quality of building engineering and can quickly change the operational characteristics of concrete.

Classification of Concrete Admixtures

There are many kinds of concrete admixtures. According to the classification, naming, and definition of concrete admixtures, concrete admixtures can be divided into four categories according to their primary functions:

  1. Admixtures for improving workability: water-reducing admixture, pumping-aid admixture, and air-entraining admixture
  2. Admixtures for adjusting setting and hardening time: setting retarder, hardening accelerating admixture and setting accelerator
  3. Admixtures for improving durability: rust inhibitor, waterproofing admixture, and air-entraining admixture
  4. Admixtures for improving other properties: air-entraining admixture, coloring admixture, expansion admixture, and anti-freezing admixture

Action Principle of Common Concrete Admixtures:

  1. The Action Principle of Air-Entraining Admixture

To solve the problem of insufficient fluidity of concrete in construction site pouring, timely mixing of an air-entraining admixture can adjust the mixing performance of concrete. An air-entraining admixture is a surfactant containing anion. When an air-entraining admixture is added during stirring, many tiny bubbles brought by surfactant are uniformly dispersed in concrete. The mixed air-entraining admixture dissolves in water and forms a stable liquid film through a chemical reaction, enhancing the contact area between liquid and outside air. These bubbles can significantly improve the workability of concrete.

  1. The Action Principle of Setting Retarder

There are two kinds of setting retarders, according to classification: inorganic and organic. Organic setting retarders are often used in the market. After being added into concrete, organic setting retarders directly develop hydrophilic films with the same charge on cement particles’ surface, which hinders the dissolution and condensation between cement particles. After the inorganic setting retarder is added into concrete, a chemical molecular film that is difficult to dissolve is formed on the cement particles’ surface. This newly developed chemical molecular film can prolong the regular hydration and hardening time of cement, reduce the early hydration heat generated by cement, and ensure that the on-site mixing concrete has enough time to maintain plasticity for pouring. Retarders are often used in hot summer because of their seasonal restrictions. In mass concrete construction, a builder should pay attention to controlling the amount of setting retarder, which directly impacts concrete’s early strength.

  1. The Action Principle of Hardening Accelerating Admixture

Many kinds of hardening accelerating admixtures produce different chemical reactions in various concrete types, which can quickly shorten the setting time of cement and make concrete have early strength conditions.

  1. The Action Principle of Composite Expansive Admixture

After a proper amount of composite expansive admixture is added into concrete, ettringite crystals react with minerals in cement, which can rapidly improve the early strength of concrete and increase cement’s internal volume. After a period of chemical reaction, relatively stable power is finally formed.

The amount of composite expansive admixture is directly related to the dry shrinkage and low water-binder ratio of concrete. When the composite expansive admixture is put in too much, it may lead to the expansion stress being far greater than the concrete structure’s bearing capacity, which will lead to cracks and affect the durability and strength of the concrete system.

  1. The Action Principle of Water-reducing admixture

Water-reducing admixture has good water reducing effect in concrete engineering and directly impacts the workability of concrete. There are useful active substances on the surface of the water-reducing admixture. Under the chemical action of active substances, cement particles in concrete are adsorbed by water-reducing admixture. Separated under the action of active substances of water-reducing admixture, the surface tension between cement and water is reduced, which enlarges the contact area between them. The water wrapped in cement particles is released for full reaction. The effect of lowering cement or water consumption is finally achieved under the condition of keeping the strength unchanged.

The production standard of MIKEM concrete additive far exceeds the specific requirements specified in relevant standards. The flexural and compressive strength, density, and resistance to harmful substances of concrete are remarkably improved. Therefore, we can ensure that concrete members have higher durability. MIKEM concrete additive can also provide the surface quality and coloring effect of concrete and a more efficient and low-cost manufacturing process. It opens a new height for your position among architects and contractors.

MIKEM concrete additive is especially suitable for projects requiring high durability and aesthetics. Compared with the traditional additives, MIKEM concrete additive can make the concrete surface smoother and brighter, especially ideal for projects involving white cement or colored concrete. Our products can be designed in various styles for you and your customers to choose from because of their high bending strength and compressive strength.

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