The use of silicates for insulation of foundations, its features, advantages and disadvantages, surface cleaning and methods of its processing. Waterproofing a foundation with liquid glass is a way to protect a building from flooding and destruction of its underground part by groundwater. We will tell you about the features of this type of work and the technology of their production in our today's material.
Features of foundation insulation with liquid glass
Sodium and potassium silicates are called liquid glass. For implementation, it comes as an alkaline solution of gray-yellow color and thick consistency. Liquid glass is produced from a lump of silicate formed during the sintering of sand, soda, salt solutions and modifiers. The material is brought to a liquid state in an autoclave by cooking under high pressure.
In addition to waterproofing, a liquid glass film applied to the surface of the foundation is able to protect it from fire, fungus and chemicals. Due to their composition, silicates, when solidified, form a monolithic coating of the smallest crystals that fill all the cracks and pores of the foundation surface, preventing the penetration of negative influences from the soil and the environment to it.
Both types of liquid glass differ from each other in their properties and applications. Sodium silicate, or soda glass, has better adhesion, so it comes into contact with many minerals more easily. This property makes the material useful for waterproofing and reinforcing concrete foundations.
Potassium glass resists oxidation and weathering better. Unlike sodium silicate, after hardening, it does not form glare, therefore it is widely used in the production of paints and varnishes.
When working with sodium or potassium liquid glass, it is necessary to take into account some of the nuances:
- It is not recommended to cover brickwork with liquid glass, since the composition of the waterproofing material contains substances that can have a destructive effect on it.
- When working with a solution, which contains liquid glass, it is necessary to take into account the high rate of polymerization of such a mixture. Therefore, it should be applied to the foundation with a thin layer so that it can have time to level and remove excess material.
- In the process of preparing a waterproofing mixture with liquid glass for the foundation, it is necessary to strictly observe the ratio of its components, which is prescribed by the instructions. Violation of this rule can lead to zero work results.
- When choosing liquid glass, one should take into account the area of its future application: sodium silicate has high adhesion to minerals, and potassium glass is optimal for use in an acidic environment.
- When purchasing a high-quality material, it should not have foreign inclusions and lumps, its density should correspond to the data of the technical passport.
Silicate foundation waterproofing can be done in three ways:
- In the form of coating insulation, which is performed if an upper protective layer of another material, for example, roofing material, is provided for the foundation. In this case, it is covered with two layers of glass with a brush or roller.
- In the form of a base, which is created by mixing a solution with water glass. The resulting mixture hardens quickly, so it must be laid immediately after preparation. This method is good for eliminating leaks or sealing gaps between elements of a prefabricated foundation.
- As the main material for casting into formwork. Here, silicate is simply added to the concrete mix. After hardening, such a foundation forms a monolith with excellent waterproofing characteristics.
Pros and cons of liquid glass insulation
This material, performing a waterproofing function, is able to restore damaged areas of the foundation surface.
In addition, when choosing and using liquid insulation, a coating can be obtained that has the following advantages:
- Ease of application on horizontal and vertical surfaces;
- Excellent adhesion;
- Lack of harmful fumes;
- High density;
- Low material consumption and reasonable price.
The disadvantages of protecting the foundation with silicate compounds include the susceptibility of the coating to mechanical damage and the too high crystallization rate of the ready-made mixtures. Therefore, in the first case, external protection of the foundation with roll materials is required, and in the second, a certain skill in performing insulation work.
Silicate waterproofing requires care and is therefore unacceptable without careful surface preparation.
First, you need to clean the concrete from dirt, exfoliated areas and dust. If there is mold on the foundation, it must be removed, and then the cleaned surface should be treated with an antiseptic. Oil and rust stains must also be cleaned. For work, you can use a grinder and chemicals.
Better cleaning can be achieved using a sandblaster. It allows you to expose the pores of the concrete surface, thereby facilitating the penetration of the waterproofing agent into them. After sandblasting, it is recommended to wipe the foundation with a 10% solution of hydrogen chloride to remove the impurities of the abrasive material.
If the foundation has small cracks, they must be cut into a width of up to 20 mm, a depth of about 25 mm, and then filled with a mixture of silicate and mortar, taken in a 1: 1 ratio. Before applying insulation, it is necessary to ensure the protection of utilities and moisten the surface of the foundation.
Foundation waterproofing technology with liquid glass
As mentioned above, the waterproofing of the foundation with liquid glass can be carried out in three ways: by coating under roll coatings, by a penetrating solution on cement and by adding silicates directly to concrete before laying it. Let's consider each of them in more detail.
This method is used in the case when it is not possible to coat the foundation with bitumen mastic. For example, when installing a polymer coating, if its contact with the products of petroleum distillation is undesirable.
Silicate in its pure state does not serve as a protective material, but when it comes into contact with concrete, crystals are formed, which, falling into the pores of the structure, make it waterproof. In this case, 2-3 layers of liquid glass with a thickness of 2-3 mm are enough.
Insulation should be done after cleaning the foundation during preparatory work. Liquid glass must be applied to the surface of the structure with a wide brush or paint roller. When applying a multi-layer material, it is necessary to wait until each layer is completely dry in turn.
After the foundation has been treated with silicate, the dried surface of the structure should be pasted over with a roll of insulating material.
It is used to quickly eliminate leaks at the joints of prefabricated foundations or in the presence of through cracks. Before treatment with a penetrating compound, problem areas of the structure should be cleaned of dirt and cut to the depth of solid concrete. The cross-section of cracks and seams after their processing should have a U-shape.
To prepare a repair sealant mixture, you will need cement, liquid glass, fresh water. First, the liquid glass must be diluted with water in a ratio of 1:10. The resulting solution should be gradually poured into a container with cement, and then mixed until a plastic mass is obtained.
Repeated mixing is unacceptable, since it will cause the rupture of bonds of the initial crystal formation, which will lead to the loss of the mixture of its insulating properties. It must be prepared in small portions, since the hardening rate of the composition is high enough.
It is convenient to use a spatula to fill the joints and cracks in the foundation with a penetrating silicate mixture. The joints can be slightly moistened before sealing to increase adhesion. After finishing work, it is necessary to remove excess material or level it over the surface. The composition will gain final strength after complete drying.
The introduction of silicates into the mixture intended for pouring into the formwork when constructing a monolithic foundation increases the water resistance of the entire structure. Their waterproofing properties affect its entire array. However, in this case, concrete partially loses its strength, becomes more fragile. In order to minimize the negative consequences of introducing liquid glass into the working mixture, the foundation should be reinforced with additional reinforcement and the sand cushion at its base should be made twice as thick.
As a hardening and waterproofing additive, silicates should only be applied to concrete M300 or M400. The amount of silicates in the mixture should not be more than 10% of its total mass, optimally - 7%, that is, about 70 liters of liquid glass per 1 m3 concrete.
The setting time depends on the percentage of the insulator in the mixture:
- With an amount of liquid glass of 2%, concrete hardening will begin in 45 minutes, and will end in 24 hours.
- Accordingly, at 5%, the time indicators will be: 25-30 minutes. and 12-14 hours.
- At 7-8% silicate content, concrete will set in 10 minutes, and completely harden in 8 hours.
The air temperature with these indicators should be + 16-20 degrees. It will take 28 days to achieve the final strength of such concrete.
For the basic composition of the concrete mixture, cement, sand and crushed stone should be taken in the usual ratio - 1: 3: 3. Due to the fact that the speed of its setting increases sharply during modification with liquid glass, the formwork for the foundation and the reinforcing cages in it must be prepared in advance.
To create modified concrete, you first need to dilute the liquid glass with clean water and gradually add the resulting solution to the cement-sand mixture. After mixing the composition in a concrete mixer, add crushed stone or expanded clay to it, mix again and pour the concrete into the formwork.
Immediately after pouring the foundation, it is necessary to level its surface horizontally and leave it until the final hardening of the concrete. Unlike traditional laying, the mixture is not recommended to be compacted in the formwork with a deep vibrator. This can disrupt the crystallization of silicate in concrete, which can lead to a deterioration in the waterproofing properties of the structure.
After gaining strength, it is recommended to insulate the foundation with polystyrene or mineral wool slabs. Such a coating, in addition to its main function, will help to evenly distribute the load on the foundation walls from the soil and protect them from damage when backfilling the trench.
How to process a foundation with liquid glass - watch the video:
Waterproofing foundation treatment with liquid glass or adding silicates to the concrete mixture during its construction are quite acceptable and affordable ways to protect an underground structure from groundwater. Using the described technology, it is possible to qualitatively insulate not only foundations, but also basements, wells, pools, and many other structures.