Sealing and waterproofing of joints – concrete, cold and expansion joints

Types of seams, joints and junctions

Concrete is an important building material, it is durable, strong and can be formed into a variety of architectural shapes. Design considerations are necessary to ensure proper operation of the structure. Generally, any structure that is expected to be deeper than 6 meters underground will experience movement and dynamics.

Concrete must be designed and constructed to accommodate dynamics and movement: Types of dynamic load and movement:

• Shrinkage is initially rapid, less pronounced as the concrete ages.
• Creep is a phenomenon that causes a redistribution of stress away from points of intensity.
• Thermal movement is the expansion and contraction of a structure as temperature changes.
• In order to adapt the structure to movement, the structures are designed with “joints”. These joints are placed into the concrete slabs at regular intervals to prevent further development of cracks. The design of the joint is important to the functioning of the overall structure - Sealing these joints is a necessity.

Based on the above, various seams are formed in concrete and other structures.

There are different types of seams and joints:

• Expansion joints are separations between adjacent parts of a structure to allow movement during the dynamics of the structure.
• Control joints – designed to prevent accidental cracks in concrete to facilitate filling after curing.
• Construction, cold, process or concreting joints are stopping points in the construction process where new concrete is poured against existing concrete.
• Installation joints are installation gaps or junctions that must be filled with insulating materials.

Correct cutting

To make a concrete screed strong, wear-resistant, reliable and resistant to all kinds of loads, you need to use only high-quality materials. But you will also need to pay special attention to the seams. It is important to strictly follow the rules for cutting them:

• A technological method to prevent cracks in concrete is carried out immediately after laying the mortar or on a well-hardened composition that has gained maximum strength. In the latter option, cutters are used for asphalt or concrete pavement.
• A couple of hours after the cement masonry has set, a test cut is made, and if the filler particles do not fall out, then the seam is cut.
• After laying the mortar, the groove is cut using a cutter, and after complete hardening, the semi-sawing method is used.
• The depth of cutting suture joints is 1/3 of the thickness of the set concrete.

What materials are used for waterproofing seams and joints

• Waterstop - This is a special waterproofing tape made from plasticized PVC or polymer materials. Waterstop is used mainly in monolithic construction and is laid in cold and expansion joints in order to serve as waterproofing.
• Bentonite swelling cord is a flexible rubber or rubber waterproofing profile that swells when exposed to water or moisture. When the bentonite cord swells, it serves as a waterproofing barrier, preventing water from passing through. Bentonite or swelling cord is designed for waterproofing cold concreting joints.
• Waterproofing tape - waterproofing TPO tapes withstand the dynamics and movement of seam walls in various directions, while maintaining a high degree of sealing.
• Sealants – when it comes to sealing joints, non-shrinking and expanding sealants are mainly used. When moisture enters, expanding sealants have the ability to expand, preventing moisture from passing through.
• Injection waterproofing - Injected into the seam under pressure using equipment, through packers or pre-prepared tubes inside the seam. It is used to fill all voids, microcracks and pores of concrete.

You can find out more about Injection Waterproofing here – Injection Waterproofing.

Characteristics of epoxy grout

The material consists of the main components: epoxy resin and hardener. Based on this, the grout is called two-component. The mass also contains quartz sand and pigment. These are auxiliary components.

Resin and hardener - these substances are contained separately, because they immediately react, resulting in a material that has a limited period of use, because it dries quickly.

Two-component tile grout has a number of technical characteristics:

• increased strength;
• resistance to aggressive chemicals;
• the material is non-hygroscopic (does not absorb moisture);
• the surface of the coating is smooth;
• high wear resistance;
• there is no shrinkage when applied to the surface to be treated;
• cracks do not appear as the material dries;
• high adhesion;
• wide range of operating temperatures: -20…+100°С;
• a large number of flowers.

The listed properties appear only after combining the epoxy resin with the hardener. Separately, these substances are not used for grouting tiles. When epoxy resin and hardener are combined, a cross-linked polymer is formed. This results in excellent waterproofing and strength characteristics.

Technology of waterproofing and sealing various types of seams and materials used for this

In fact, construction seams and joints are the most common cause of structural leaks below grade. Therefore, protecting joints in concrete is vital, especially given the disastrous consequences if they are ignored or if the wrong material is used to seal the joints. Each type of seam has its own sealing technology.

Next, we will study all the methods of waterproofing joints, junctions and seams and the materials used.

Sealing and waterproofing of concrete joints and joints in concrete

In order for a concrete structure to be completely waterproof, all its elements, including construction, cold and expansion joints, must be protected. The required waterproofing systems are usually supplemented in the technical specifications for the project. Swellable cords, waterproofing tapes and sealants are commonly used to seal concrete joints. If during the construction of a building, the builders did not pay due attention to the seams and joints, then they may subsequently leak.

Sealing and waterproofing of expansion and expansion joints

Although buildings are often constructed using flexible materials, large building sizes require structural expansion joints, so-called expansion joints. These seams are needed to ensure that the constructed structure does not crack, since the constructed building is subject to various influences during its service life, such as:

• Ambient temperature during construction and the expected temperature range during the life of the building;
• Seismic phenomena;
• Uneven soil settlement and other impacts that can cause dangerous dead loads that reduce the load-bearing capacity of structures.

Expansion joints are:

1. Periodic ruptures in the structure of buildings.
2. A gap in a building structure provided by the design, architect or engineer to allow movement of the building due to changes in temperature, ground settlement, etc.
3. A unit designed to safely absorb thermal expansion and contraction of various building materials.

Expansion joints are commonly found between sections of slabs, bridges and other structures. “Assembly” can be as simple as caulked division between two sections of the same materials. In concrete and concrete block construction, the term “control joint” is used and serves similar purposes. Throughout the year, building facades and concrete slabs will expand and contract due to warming and cooling throughout the seasons. Structures will crack under the stress of thermal expansion and contraction if expansion gaps are not provided.

When designing a building, it is very important to take into account those same expansion joints and their proper sealing and waterproofing, since they are one of the weakest points in the building’s structure, and if improperly sealed, they will let a large amount of water into the building.

Today, many builders and designers ignore those very deformation nodes and do not pay due attention to their sealing, as a result of which the majority of premises put into operation, where those same seams pass, leak and require waterproofing.

Technology of sealing and waterproofing expansion joints – How and with what materials this work can be performed:

From the outside: If there is access to this unit from the outside, then it is best to use a system of a special elastic tape for waterproofing expansion joints and epoxy glue (to fix it), similar to the Sikadur-Combiflex system, which consists of a waterproofing TPO tape and a specially designed epoxy adhesive composition Sikadur. This tape can withstand significant and uneven movements of the seam walls in various directions, while maintaining a high degree of sealing.

From the inside: If there is no access from the outside to the expansion or expansion joint, then seal it from the inside of the room. For this purpose it is best to use a combination of methods and materials:

1. Unstitch and clean the seam;
2. Compact the inside of the seam with a swelling profile using the vilatherm type - this is done so as not to fill the seam to its entire height, but only its edge zone;
3. Compact another swelling profile;
4. Seal the remaining gap with a special non-shrinking compound or expanding sealant;
5. Make holes and install a packer around the perimeter of the seam, so that, when performing an injection, the injected composition gets between the two installed seals;
6. Perform injection waterproofing using special equipment through the installed packers, a gel composition of the HydroInject type (injection waterproofing from the German company Hydro) is supplied into the seam, which spreads throughout the entire seam, hardens (without losing elasticity) and prevents water from entering the room;
7. Installation of waterproofing TPO tape with epoxy adhesive, similar to the Sikadur-Combiflex system.

Waterproofing cold joints and concreting joints

Cold seams in concrete form when there is a break in the concreting process. For example:

• First, we fill the foundation slab, and then we begin to fill the walls - a cold seam is formed at the junction of the foundation slab and the wall.
• When pouring concrete walls, there is a break in work - here a cold seam is formed at the junction of the old and new concrete pouring.

Cold seams are weak points in the structure, and in the absence of good external waterproofing, they will let water through first. To protect cold seams during construction, it is necessary to lay a so-called swelling cord at the joints, following the established standards and technology for its laying.

If during concreting there were violations of the technology for sealing cold joints, as a result of which it is necessary to eliminate leaks at the joints of the cold joint from inside the room, then the following stages of work must be followed:

1. The cold seam must be embroidered (make a small groove 3x2cm) in the shape of a swallow;
2. The made groove must be cleaned and dust-free;
3. Compact layer by layer with a non-shrinking compound or expanding sealant, like HydroExpand;
4. Mark injection centers along the perimeter of the seam in 0.20 cm increments in a checkerboard pattern;
5. Drill holes - holes and install a packer (hollow tubes for wire injection composition);
6. Injection waterproofing - injection or injection under pressure (using special equipment) of polyurethane compounds, like HydroInject, into a cold joint;
7. Removing packers;
8. Seal injection centers with expanding or non-shrinking sealant.

In addition to sealing concreting joints using sealants and injection compounds, it is also recommended to apply a special protective membrane from waterproofing compounds that operate on negative water pressure (from outside to inside the room), similar to cement-mineral two-component waterproofing.

Waterproofing of interblock seams

If the walls of the house are made of blocks, then they have so-called interblock seams that require special attention. Interblock seams are those seams that are located between concrete blocks. When constructing the walls of a basement or basement from blocks, it is very difficult to lay the blocks so that the mortar underneath them lies everywhere evenly and perfectly; accordingly, when carrying out external waterproofing with built-up or rolled materials, most likely in places where the mortar lies unevenly, a void may form, which will be a weak point for the penetration of moisture and water into the room through the interblock seams.

If the house is already standing and the interblock seams allow moisture and water to pass through, then to seal them, the following technology should be used:

1. The cold seam must be unstitched (make a small groove 3x2cm);
2. The made groove must be cleaned and dusted
3. Compact layer by layer with a non-shrinking compound or expanding sealant, similar to HydroExpand
4. If the interblock joints are severely damaged, or there are damage and microcracks in the blocks themselves, then the interblock joints can be additionally injected.

In addition to sealing interblock concreting joints using expanding and non-shrinking sealants, it is also recommended to apply a waterproofing compound operating under negative water pressure, such as a cement-mineral two-component waterproofing.

Waterproofing of balcony and assembly joints

When installing windows or balconies, so-called installation joints are formed. If these seams are not sealed in time with sealants or foams, then water may leak through them in the future.

Here you can download several state regulations that describe in detail the technology for sealing balcony seams and assembly seams:

GOST 30971-2012 Seams of assembly units connecting window blocks to wall openings. General technical conditions

GOST R 52749-2007 Window installation joints with vapor-permeable self-expanding tapes. Specifications

Pros and cons of using epoxy grout

Positive traits:

• strength, under the influence of increased mechanical loads the layer does not deform;
• versatility: the mixture can be used to decorate coatings made of different materials outside and inside the object;
• working with epoxy grout is done without much effort, it does not require experience to prepare the mixture, you do not have to calculate the number of components, since they are already specified by the manufacturer;
• long-term operation;
• resistance to ultraviolet radiation;
• the material retains color throughout its entire service life;
• ensuring waterproofing of seam joints;
• large selection of shades;
• high adhesion;
• the coating is much easier to clean from contaminants during operation, this is due to the smooth surface of the epoxy layer and the absence of cracks;
• resistance to alkalis and acids, which allows the mixture to be applied in rooms where there is a high risk of contact with such substances (bathroom, kitchen).

Grout can be used for different purposes. It improves the appearance of the coating and gives it completeness; allows you to hide minor defects on the surface; protects against moisture; It is used in the same way as glue, which allows you to further strengthen the coating. However, there are also disadvantages to this type of material:

• the mixture instantly hardens, therefore it requires increased care and quick reaction, since it is necessary to immediately remove excess substance from the tile;
• special tools are prepared for the work and special chemicals are used;
• difficulty in cleaning, due to increased adhesion and strength of the material;
• high cost of the mixture.

What kind of grout will you use?
Epoxy Cement

Waterproofing seams from the inside

If we are talking about sealing seams from the inside, then most likely we are talking about repairs and eliminating leaks in places where there are joints, joints and seams. Waterproofing from the inside is carried out if access to the seam from the outside is impossible.

Work from the inside is carried out mainly by opening the seams, sealing them with a swelling cord or sealant, as well as by injecting 2-component polyurethane resin or gel (where there is dynamics).

When carrying out work from the inside, certain technological processes should be followed, depending on what kind of joint we are dealing with. For each type of seam, different technologies for its sealing and waterproofing are used; you can read in detail about each in the continuation of this article.

Manufacturers

Several of the most famous foreign and domestic manufacturers:

• Litokol (Italy). The material is stored for two years at a temperature of +5°C. The temperature must not be allowed to drop, otherwise the components will become hard and lose all their properties. This manufacturer offers grout in 103 colors, including various additional effects. Suitable for both indoor and outdoor use. The price ranges from the smallest (1 kg) - 1300 rubles, the medium (2.5 kg) - 3500 rubles. up to the largest package (5 kg) – 4000 rubles. Positive qualities of the brand's products:
  No smell.
• Suitable for use in rooms with poor air ventilation.
• Easy to apply.
• High resistance to temperature changes and high humidity.

• Mapei Kerapoxy. The main difference between the products of this manufacturer is that the grout has minimal grain size. However, the range of products is limited: only 26 colors are presented. The manufacturer produces a grout of three components, which is even more resistant to acids and other aggressive chemicals. Price 3 kg – 3500 rub., 10 kg – 5600 rub.

• "Diamant" (Russia). The grout is available in an assortment of 46 colors. But it can only be used to treat the bathroom. Sold in packages of 2.5 kg - from 2000 to 5000 rubles.

• "Basic." The epoxy grout from this company is characterized by high resistance to temperature changes (from – 50 to + 75°C), elasticity, hydrophobic properties and is not prone to the development of fungus. The solution is usable within an hour. The grout is available in 29 colors, packing 2.5 kg - 2000 rubles. In general, it has all the properties that are characteristic of epoxy.

• "Fugue". The product has all the properties characteristic of epoxy grout. Suitable for processing both indoors and outdoors. The solution is usable within two hours. The material is available in 32 colors. The cost varies significantly, for example, in online stores you can purchase 2.5 kg of dry mixture for literally 2,000 rubles, while in retail stores the product will be much more expensive.

Whatever company the buyer chooses, when starting to work, it is necessary to read the instructions on the packaging and act on them.

Waterproofing foundation joints, walls and basements

As mentioned earlier, seams are one of the weakest points in any structure. Seams exist in walls, foundations and basements, and it does not matter what material the walls of the basement or foundation are made of.

Waterproofing foundation joints

Foundations are different, but regardless of whether it is a strip foundation or a monolithic foundation slab, there may be seams.

There are several types of joints in the foundation:

• Deformation – used mainly when it comes to a large building or structure.
• Cold or concreting seam - although when pouring the foundation, it is not recommended to take breaks and pour the foundation in several stages, sometimes it is necessary to carry out concreting work in several stages with breaks. This scheme is mainly used when working with objects of large area or complex geometric shape, where continuous concreting in one layer is technically difficult or completely impossible.

The method for sealing these seams was described above.

Waterproofing wall seams

During the construction of walls, various types of seams can form, depending on how and with what material those same walls were erected.

• Monolithic walls - When pouring concrete walls, seams may form if the walls were poured in several stages. When pouring walls from a monolith, at least 1 cold seam almost always forms - this is the joint between the slab and the wall, since the walls are poured separately from the base floor.
• Walls made of FBS blocks - here we are talking about the cold joint between the slab and the wall, as well as the seams between the blocks that form the walls.
• The walls are made of brick - here there will be seams both between the bricks and at the junction between the floor and the wall.

To waterproof and protect cold slab-to-wall joints and other joints, when constructing walls, the jointing method, layer-by-layer sealant sealing and injection (if necessary) are used.

Waterproofing basement joints

If there are leaks in the basement, then first of all, you need to decide from which places or seams in the basement. If water comes from below, at the slab-wall junction seam (this happens in most basements), then it is necessary to unscrew the lower wall-to-slab junction seam and seal it with a swelling cord or expanding sealant, but also inject it.

Important: When jointing a cold seam, it is not enough to make a 3-5 cm groove, then seal the swelling cord into it, sealing it with a non-shrinking compound, or initially seal it layer by layer with a special expanding sealant - You need to additionally perform an injection (mainly with a 2-component polyurethane resin, like HydroInject - this technology will serve as a cut-off and will not allow capillary moisture to rise up the wall. The groove produced is not made across the entire thickness of the wall and, accordingly, in the absence of an injection (as a cut-off), capillary moisture will pass directly behind the groove you made and will come out as a wet spot, just above yours seam

Choosing the appropriate composition

First of all, you need to pay attention to the type of main components that the epoxy-based grout contains. The composition of such materials may include cement, various additives that increase elasticity and improve other properties. The cost of grouting will depend on this. Another factor is brand. Common options:

• Mapei Kerapoxy Design;
• Litokol Litochrom Starlike;
• Diamond.

The cost varies between 900-1100 rubles. per 1 kg of substance. The grout does not have to be updated regularly, since it does not lose its properties throughout its entire service life.

By comparison, the cement version quickly deteriorates. This substance loses strength, over time it begins to absorb moisture more strongly, and cracks form on the surface.

You also need to calculate the volume of grout required to finish the wall or floor. In this case, information from the manufacturer is taken into account. In most cases, the label indicates how much substance is consumed per 1 m². Based on this, you need to calculate the total amount of grout per area to be treated. If you immediately purchase the required amount of material, you can reduce the surface finishing time.

Work on sealing and waterproofing joints

Each type of seam has its own set of works and its own technology, with the help of which it is protected from future leaks. Seams are the most vulnerable places in the structure of your home; therefore, if the work on sealing the seams is performed poorly, in the future they will allow water or moisture to pass through and will require expensive repairs. Based on the above, in order to carry out these works efficiently, it is necessary to invite a professional waterproofing company with the appropriate experience and qualifications.

Waterproofing seams prices, price and cost of 1 linear meter

Cost calculator for waterproofing joints

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Calculation of the cost of injection and suture waterproofing