Concrete water-reducing agent refers to the ability to reduce the water requirement of concrete under the condition of maintaining the same fluidity after being added, thereby improving the strength and durability of concrete, or under the condition that the amount of cement and the water-cement ratio are unchanged. , Add an admixture to improve the fluidity of concrete and improve the workability of concrete.
1. Lubricating effect: The polar hydrophilic groups in the water reducer are adsorbed on the surface of the cement particles, and it is easy to associate with water molecules in the form of hydrogen bonds. The effect of this hydrogen bonding association effect far exceeds the molecular attraction between water molecules and cement particles. After the cement particles absorb enough water-reducing agent, with the association effect of R-SO3θ and the hydrogen bond in the water molecules, plus the hydrogen bond association between the water molecules, the surface layer of the cement particles will form a stable layer of solvated water Membrane, this layer of film has a three-dimensional protection effect, blocking direct contact between cement particles, and lubricating effect between particles.
2. Wetting effect: After the cement is mixed with water, the particle surface is moistened by water, and its moist condition has a great influence on the characteristics of the freshly mixed commercial concrete. When this diffusion and wetting occurs naturally, the surface free can be calculated by the equation pointed out by Glbbs The amount can be reduced.
3. Water reduction effect. When commercial concrete is mixed with high-efficiency water-reducing agent, the water-cement ratio can be obviously reduced under the condition of maintaining fluidity. High-efficiency water-reducing agents can achieve a water-reduction rate of 10% to 25%, while ordinary water-reducing agents have a water-reduction rate of 5% to 15%. High-efficiency water-reducing agents are also known for this. The main reason for the water-reducing effect is the absorption and dispersion of water-reducing agents by commercial concrete.
4. Plasticizing effect. After the commercial concrete is mixed with the water-reducing agent, the fluidity can be added while maintaining the water-cement ratio unchanged. Normal water-reducing agent can increase the slump of fresh mixed commercial concrete by more than 10 cm while maintaining the amount of cement used. High-performance water-reducing agent can be configured as commercial concrete with a slump of 25 cm.