How do silicone hydrophobic agents work in mortar?

Water repellent is a common additive in building materials, especially in mortar. Its main function is to improve the waterproof performance of mortar, improve its durability and stability, so that it can maintain excellent performance in humid environments. So, specifically, how do hydrophobic agents work in mortar?

Silicone Hydrophobic agents are substances that make materials repellent to water. It can change the surface properties of materials, making the surface less wettable by water. When these materials come into contact with water, the water will form beads on the surface due to surface tension, rather than immediately penetrating into the material. This is what we often call the "pearl shape".

What changes will happen when we add a silicone hydrophobic powder to the mortar?

The water absorption of the mortar will be significantly reduced. This is because the silicone  hydrophobic agent changes the properties of the mortar surface, making it less likely to be wetted by water. In this way, even if it is washed by rain or in a humid environment, the mortar will not easily absorb water, thereby avoiding expansion, deformation or cracking caused by water.

The impermeability of the mortar will be improved. Since the mortar surface is not easily wetted by water, the mobility of water on the mortar surface is enhanced, making it more difficult for water to enter the interior of the mortar through the capillary pores. This is like an invisible protective film, effectively blocking the intrusion of water molecules.

The weather resistance of the mortar will also be improved. Due to the presence of the silicone hydrophobic agent, the mortar can maintain stable performance when faced with natural environmental factors such as temperature changes and humidity changes. This is very important for the durability.

Mortars using silicone hydrophobic agents also have good workability. Because it does not easily absorb water, the consistency and fluidity of the mortar can be well controlled during the mixing and construction processes, thereby improving construction efficiency and reducing waste.

Since the water-repellent agent is so good, should we add more to improve the performance of the mortar? actually not. While silicone hydrophobic agents can bring many benefits, more doesn’t mean more is better. Too much hydrophobic agent may affect the adhesion of the mortar and even cause the strength of the mortar to decrease. Therefore, we need to reasonably select and use hydrophobic agents according to specific environments and needs.

The role of water repellent in mortar is multi-faceted. It can significantly improve the waterproof performance of mortar, enhance its durability and stability, and improve its construction performance, thereby making our buildings safer and more durable. Only by using the water-repellent agent rationally and avoiding too much or too little can it maximize its effect in the mortar.