In the preparation of concrete, mortar, and paste, the addition of a small amount of water reducer can change the properties of concrete, mortar, and paste. Therefore, water reducer belongs to concrete construction chemicals.
Water reducing agents are also known as plasticizers or dispersants. Adding an appropriate amount of water-reducing agent when mixing the concrete can disperse the cement particles uniformly and release the water wrapped by the cement particles, thereby significantly reducing the water consumption of the concrete.
The main functions of the water reducer are as follows: increase hydration efficiency and reduce unit water consumption; increase concrete strength and save cement consumption; improve the workability of concrete that has not yet solidified, prevent the segregation of concrete components; improve the impermeability, Reduce water permeability and avoid leakage of concrete building structures; increase the durability of concrete and increase the resistance to chemical corrosion; reduce the shrinkage rate of concrete solidification, prevent cracks in concrete components; improve frost resistance, which is conducive to winter construction.
When cement comes in contact with water, different charges on the surface of the cement particles attract each other, which causes the particles to flocculate or agglomerate. A large part of the water is absorbed during this process, leading to a cohesive mixture and reduced slump.
The superplasticizer essentially neutralizes the surface charge on the solid particles and makes all surfaces similarly charged. Since particles with the same charge repel each other, they reduce the flocculation of the cement particles and allow better dispersion. They also reduce the viscosity of the paste, resulting in a greater slump.