Sealant for concrete - varieties, description. Bases made of concrete are solid and solid, but not completely elastic. Special expansion joints are made on the concrete surface to improve its qualities. They are capable of performing various tasks (insulation, shrinkage or zoning), but then require protection from the negative effects of clogging and moisture. Concrete Sealant is an extremely effective grouting agent for cementitious coatings.
Similar means can be used to process expansion joints and cracks inside concrete.
In order to process concrete surfaces, paste-like viscous substances should be used that have sealing properties. The compounds should be applied to substrates, both fresh and old ones, as well as to fill horizontal / vertical joints with different depths and widths, joints and cracks. Sealants are able to set and harden quickly, thus providing the coating with reliability and protection.
For concrete processing, mainly elastic compounds are used, which have a degree of deep penetration into the pores of the material, and also leave a thin layer of protection on the processing surface.
Sealants can be classified according to several criteria, with all agents generally divided into one-component and two-component. Their main difference is the drying rate and strength. After the sealant is completely cured, it will prevent cracking in the concrete, will not allow moisture to pass through, and all chemicals will remain inside the cement base.
Why are expansion joints needed
The concrete surface is durable and strong, and can also withstand high compressive and tensile loads. But due to the fact that the temperature regime will change, the freezing and thawing cycles contribute to the fact that the cement base is cracked.
To prevent this, expansion joints should be made in the concrete. This is surface fragmentation (and targeted), which makes it possible to weaken the external and internal impact, and will also prevent changes in the geometry of concrete slabs.
Expansion joints can also be classified:
- Structural - are required in order to divide the surface into separate areas, and they are laid at different times. This helps to reduce the likelihood of cracking.
- Compensation (shrinkage) - after the cement hardens, it shrinks.
Grooves in the concrete surface help to reduce the shrinkage of the substrate and also increase its load bearing capacity.
- Insulating - are required in order to make the zoning of the cement screed from the rest of the structures.In places where different types of foundations are interfaced (for example, floor and column), the level of pressure on the concrete increases.
Sealant for processing expansion joints on concrete floors helps to reliably protect expansion joints, and also prevents moisture and various debris from penetrating under the top layer of cement. Sealing gaps helps to strengthen the screed, prevents rapid abrasion, and also helps prevent the formation of chips at the joints as a result of mechanical damage.
It is for this reason that the use of a sealant is a must for effective concrete protection.
On the construction market you can find a wide range of sealants for joints in concrete.
The classification of compositions is quite large, since they can be divided into different groups according to several criteria:
- By the method of influence on the base, which has undergone treatment - surface substances create a protective and waterproof film, and compositions with deep penetration help fill the pores of the concrete from the inside, while they will not let moisture inside.
- According to the component composition, one can distinguish sealants for joints in concrete, made on the basis of acrylic (for interior use), based on polyurethane (have high elasticity) and thiokol substances. All funds will have different specifications.
- One-component sealants, which are ready to use, and two-component substances, which must be mixed in the specified proportions before application. They have different indicators of elasticity, setting time and degree of elasticity.
When choosing a sealant for concrete, it is imperative to take into account the field of application of the product - external or internal work, old or fresh screed. Means for processing concrete will adhere perfectly to metal, wood and other surfaces, therefore, to some extent, they can be considered universal.
Among the means for sealing on the construction market, acrylic compositions are the most environmentally friendly.
Often they are advised to be used in order to carry out internal work, since it is such products that are less resistant to temperature extremes and high levels of humidity. One-component substances are used to seal gaps in concrete when processing joints.
Before applying the sealant, it should be thinned with water, and then it will acquire a fluid consistency. The product can be poured into cracks and crevices in concrete, and then everything should be carefully leveled. Once the surface is hard, there will be a smooth layer, which can be painted if desired.
The area of application of acrylic sealants is joints on a cement surface. There are no solvents in the composition at all, therefore staining is permissible.
Resistance to moisture from polyurethane is the main advantage of such a group of suture materials for concrete processing. The formulations help to provide a high level of strength for the cement screed.
Advantages of materials:
Polyurethane sealants for joints in concrete are excellently able to withstand heavy mechanical loads. In order for the application of funds to be convenient, construction syringes should be used. The formulations are not capable of reacting to chemicals - acids, oils and alkalis.
Two-component polyurethane-based sealants must be mixed in strict proportion, otherwise they will not have the required properties. The field of application is plinths, facades, floors and foundations.
Silicone sealants for concrete (joint) have maximum protection against moisture. Acid and neutral silicones can be distinguished - the second option is suitable for concrete substrates. The use of silicone acid sealants can cause soluble salts to precipitate from the cement, which can destroy the integrity of the substrate.
Features of using silicones for concrete surfaces:
- They contain antifungal components.
- "are not afraid" of the negative effects of aggressive environments.
- Can be applied over primed coat.
- The products have excellent elasticity.
Please note that silicones have a high degree of adhesion, and the formulations are capable of demonstrating high resistance to various influences.
Silicone-based sealants are widely used for wells that are made of concrete rings because they are best able to resist constant moisture.
Variety of thiokol type sealants contains polysulfides. Such substances will be characterized by high elasticity, as well as resistance to chemicals. The main producer of thiokol agents among domestic companies is Sazilast.
When two-component sealants are mixed, a flexible and highly durable rubber is obtained.
Such compositions are not able to shrink, they can remain stable even with unexpected and large temperature drops or upon contact with aggressive media. Additionally, it helps to protect the concrete from dynamic and static loads. A cement floor, after being coated with thiokol sealant, becomes much more resistant to chemical, mechanical and temperature influences.
Modified One-Part Silane are solvent-free sealants and are best suited for concrete surfaces that are in constant contact with moisture. They will be relevant to use for wells, foundations or cement tanks.
Modified silane substances have absolute elasticity and adhere firmly to the treated surface.
Immediately after applying the compound, it goes deep into the pores of the concrete, and then reliably adheres to the base. Silane can even be used underwater - sealing rings of concrete with a waterproof sealant. If the work is carried out on a dry surface, then after the sealant is applied to the cement base, it can be painted over.
The cost of sealants will directly depend on the composition, brand, country of origin.
If we talk about domestic products, it is natural that they cost an order of magnitude cheaper than imported sealants for concrete and expansion joints in it. In terms of affordability, silicone and acrylic compounds have become the leaders, the approximate cost of which starts from 130 rubles per 1 kg. More expensive polyurethane sealant - from 180 rubles per 1 kg. Thiokol products occupied the middle price category - from 200 rubles per 1 kg of the mixture. The most expensive type of sealant is silane modified products, and it costs from 710 rubles per 1 kg, but the cost is fully justified, because such a sealant for concrete is waterproof, and is also the most reliable and durable.
Any action to create coatings with full tightness begins with the fact that the base should be prepared. The composition with the best adhesion properties will not "take" on dusty or dirty surfaces. The cleanliness of the concrete will directly affect the bond strength of the surface and sealant. We present you with instructions for the use of means for sealing with a polyurethane-based sealant for sealing joints in concrete, or with substances of a silicone, thiokol, acrylic or silane modified group.
- Remove debris, dust, mortar residues from the cement.
- Avoid corrosion, oily stains, salt.
- Narrow seams need to be re-stitched to facilitate material application.
- Seams should be primed or primed.
- First mix the sealant (if two-component).
- Select the tool you need - brush, syringe, spatula.
- Fill the seam with an even layer along its entire length.
- Remove excess mass from tools before it hardens.
- Dip a spatula in soapy water and iron all joints.
- If applying two coats of sealant, they should be tucked in opposite directions.
Sealant drying time will vary depending on whether the one-part or two-part was used and the operating conditions (wet, dry, warm or cold).
Acrylic mixtures dry out in 15-20 minutes, and complete hardening will be after 2 weeks. Polyurethane sealants create a film on the concrete surface within two hours, but it will take up to 12 hours to harden. Thiokol substances will harden quickly if applied in a thin layer. Sealing the joints in the base of the concrete will increase their life and will also prevent rapid abrasion. The sealants are easy to work with and can be easily applied to the surface.
The processed joints of the cement screed have high strength and absolute moisture resistance.
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