sealing and Hydrophobic of biulding surface

Implementing sealing and controlling negative pressure and hydrophobic various surfaces of the building

Sealing

Preventing water and moisture from penetrating into the surface without creating a hydrophobic property for the surface is called sealing. Sealing is usually done reactively with silicate primers. In the sealing method without destroying the hydrophilicity of the surface. In other words, without making the surface hydrophobic. By filling the pores and capillary tubes inside the surface or creating a coating, the possibility of water penetration into the surface is eliminated.

hydrophobic

Hydrophobicity of surfaces occurs by aligning the poles and creating repulsive force and reducing the surface tension between the surface covered with hydrophobic products and the water molecule. The placement of water droplets in an almost spherical shape on the surface of the indicator.

Difference between sealing and hydrophobicity

Water absorption and its penetration in construction materials such as concrete, gypsum, stone, etc. due to the type of texture and particle size and also the presence of capillary cracks that are the factors of water transfer or absorption have long caused many problems such as efflorescence , Contamination on the surface, transfer of moisture and humidity and thus reducing the life and quality of building materials, especially in the facade and exterior surfaces of the building.

The pore size of most building materials is between 5 and 200 nm, while water molecules are less than 2 nm and contaminants that can enter the material directly or through water are often between 1 and 2 nm, which with Due to the hydrophilic nature of most mineral and natural materials used in construction, they easily penetrate into them and cause many problems.

Therefore, they have long tried to prevent the penetration of water and hydrophobic and sealing materials by using various polymer coatings such as paints and colored coatings. But firstly, due to the particles that make up these surface layers (which are generally more than 100 nanometers), they are not able to resist and prevent the penetration of free ions, and secondly, their lack of proper and long-term resistance to ultraviolet rays, which This shortens the life of these protective layers. Therefore, with the advancement of science and the use of nanotechnology, a revolution has occurred in the industry of materials and chemical additives, which also did not exclude facade protection materials.

Nano-penetrators for protection of facades and surfaces against moisture and humidity, free ions, sulfates and other corrosive and destructive agents are offered in the market on two families of water-based and solvent-based, which are monomers or polymers with a maximum size of 5 to 6 nanometers. Are included. These materials penetrate the space between the molecular particles and, by forming a membrane or mass, cause all or part of it to fill.

The filling operation is done in two ways:

1) Reactive fillers: These products include silanes, siloxanes, silicones, and silicates.
2) Non-reactive fillers: such as oils and organic products, it should be noted that this group of materials due to the high rate of decomposition by microorganisms in nature, have a relatively short useful life between 2 to 5 years.

Reactive products are grouped in two systems of water repulsion or hydrophobic and the other sealing, which due to the proximity in appearance of performance and behavior, generally their structural differences are not considered or both systems are used with the same purpose.

The maximum penetration in products that only cause hydrophobicity on the surface is 3 to 5 mm, which is not recommended for use in areas where there is a possibility of changing or decreasing the strength of the field for reasons such as severe lightning. The greater the penetration of these hydrophobic layers in the texture of the material, the higher the resistance to ultraviolet rays of the sun and therefore the amount of fall of these layers, which is an average of 5 to 10 microns per year, is reduced.

New smart sealing products include permanent smart nano-silicates.

Advantages of permanent smart nano-silicates:

1) No need to reapply and complete stability against sunlight
2) The possibility of neutralizing and removing existing efflorescence or removing sulfates from the surface layers
3) The possibility of creating sealing properties on wet and damp surfaces and removing moisture in the surface
4) No film or layer on the surface and the possibility of applying paint or coating with different chemical bases on them.
5) Increase impermeability resistance to chlorine ions up to 250% and frost resistance up to 300 glacial periods.
6) Dealing with positive and negative water pressures and preventing the peeling of paint or colored coatings due to moisture or gas pressure resulting from surface respiration.

The role of silicate primers in removing negative pressure as a primer before applying various types of building paints and industrial flooring

Most primers on the market are not able to withstand the negative pressure of water and steam as well as efflorescence ; Therefore, it is better to apply silicate primers on the surface first and then apply other coatings on these primers.

Here it is necessary to pay attention to the basic point of whether the desired paint and coating adheres to the surface of building materials by creating a chemical bond, or whether by penetrating the pores of the surface, it only establishes a physical connection with the surface and thus adheres to the surface.

According to this important point, we divide construction and industrial paints and coatings into two categories and explain the role of penetrating primers as primers before applying these paints and coatings.

1- Paints and coatings that adhere to the surface of building materials by creating chemical bonds

Paints and coatings such as epoxy and polyurethane can be chemically bonded to the surface of materials due to the high polarity of their constituent resins and also due to the presence of functional groups such as hydroxyl groups, etc .; Therefore, impermeability of the surface by silicate primers not only does not limit the adhesion of paint and coating to the surface, but also fills the internal pores of the surface to prevent negative water and steam pressure and also the possibility of efflorescence behind this type of coating. For this reason, in order to increase the useful life of these paints and floors, it is recommended to use silicate primers before applying these types of paints and floors, especially in places where there is a possibility of efflorescence and negative water pressure.

2- Paints and coatings that mostly adhere to the surface of building materials through physical connection

For example, acrylic paints and coatings, due to the nature of their constituent resin, do not have the ability to form a strong chemical bond with the surface of the material; Therefore, in order to adhere to the surface of the material, they must be able to penetrate the surface of the material to some extent by filling the pores inside the surface and create mechanical clamps.

What is sealing?

Preventing water and moisture from penetrating into the surface without creating a hydrophobic property for the surface is called sealing.

What is hydrophobicity?

Hydrophobicity of surfaces occurs by aligning the poles and creating repulsive force and reducing the surface tension between the surface covered with hydrophobic products and the water molecule.