The mechanism of action of Water Retaining Agent For Ready-Mixed Mortar on the crack resistance of mortar
1. Maintain moisture and reduce shrinkage cracks
Water Retaining Agent For Ready-Mixed Mortar can significantly reduce drying shrinkage cracks in mortar caused by rapid water loss. During the hardening process of mortar, the evaporation of water will cause volume shrinkage. The water-retaining agent is like a "small reservoir" that can effectively lock the moisture in the mortar so that the moisture inside the mortar can be released slowly over a longer period of time. For example, when the external environment is dry, the water in the mortar without a water-retaining agent will evaporate quickly, and the volume of the mortar will shrink sharply, which can easily cause cracks. Mortar containing water-retaining agents, due to its water-retaining effect, can maintain a relatively stable humidity environment inside the mortar, reducing the dry shrinkage deformation of the mortar, thus reducing the possibility of dry shrinkage cracks.
2. Improve the cohesion of mortar
Water retaining agents can enhance the cohesion of mortar, which is also critical for crack resistance. It can make the cement, sand and other particles in the mortar bond together better. When the mortar is subjected to external forces, such as expansion and contraction caused by temperature changes or tensile stress caused by deformation of the base layer, good cohesion can prevent the separation between the internal particles of the mortar. It's like adding a "glue" to the mortar, making it a tighter whole. This tight structure can better resist cracking caused by external factors, disperse possible cracks into tiny areas inside the mortar, and avoid the formation of macro cracks.
3. Optimize the hydration process and enhance the internal structure
Water retaining agents also have a positive influence on the hydration process of the mortar. It allows cement and other cementitious materials to undergo hydration reactions in a more suitable humidity environment. With sufficient water supply, the cement hydrates more fully and generates more hydration products. These hydration products can fill the pores inside the mortar and make the internal structure of the mortar denser. A dense mortar structure is like a strong fortress that can effectively resist cracks caused by internal stress changes. At the same time, this optimized hydration process can also increase the strength of the mortar and further enhance its crack resistance.
4. Adjust humidity gradient and reduce stress concentration
Between the surface layer and the interior of the mortar, a humidity gradient often forms due to different evaporation rates of water. Water-retaining agents can adjust this humidity gradient and reduce the difference in humidity between the surface and interior of the mortar. When the humidity gradient is large, large internal stress will be generated, and this stress concentration can easily lead to cracks. By retaining moisture, the water-retaining agent makes the humidity changes on the surface and inside of the mortar more synchronized, thereby reducing the stress concentration caused by the humidity gradient and reducing the risk of mortar cracking.
