Waterproofing concrete slab joints

Waterproofing concrete can be implemented at the construction stage of the building or during operation. In practice, maximum efficiency can be achieved using an integrated approach.

Reinforced concrete products can be processed using the following materials:

sheet and roll coverings (geosynthetics or PVC membranes);
liquid compositions – bitumen mastics, liquid rubber;
sheet metal (metal-based materials are not used for waterproofing the floor);
mixtures based on bentonite clay;
mineral-based binders;
penetrating mixtures;
Waterproofing concrete is used for surface treatment of reinforced concrete structures.

Waterproofing concrete joints can be implemented:

at the joints of walls and foundation slabs of a house, floor slabs, lintels, etc. (with materials like “Dehydrol”). To waterproof the joints of concrete slabs, grooves of 20x20 mm/30x30 mm are installed. Material consumption 0.8 kg/m.p of concrete;
on prefabricated reinforced concrete structures. Recently, special sealing tape has been used to waterproof joints. The material is fixed on the surface of the structure in the abutment zone, after which it acquires waterproof properties;
joints of balcony slabs, various canopies and walls, other external seams, including foundation ones, are best treated with coating waterproofing.

Insulation of floors must be carried out using penetrating materials. The slabs are processed from below or from the outside . In technical rooms it is better to use rolled materials or bitumen mastic.

Type of foundation waterproofing

Two main types of insulation are used - vertical and horizontal waterproofing of the foundation; both methods are not always used in construction.

For horizontal processing, only materials intended for this purpose are used, mainly weld-on or self-adhesive rolls. Vertical includes coating, screen, internal, external waterproofing.

There are several options to protect the foundation from water penetration:

Coating is the most common method that gives a good long-lasting effect and is easy to do with your own hands;
Penetrating method – cutting off excess moisture using new technology. The principle is that after treatment, concrete, when interacting with water, is covered with a protective layer and crystallizes, closing the most microscopic pores;
Roll processing. It is not durable, but it is a very convenient and quick way to create a barrier to water penetration. Rolled or coating materials are used for work.

It is worth understanding that waterproofing the foundation slab begins only after the concrete has completely dried.

Roll processing today uses materials such as stekloizol, rubemast. It gives the structure good strength and is convenient to use under a slab. It is laid on a sand and gravel cushion; no additional screed is needed. Each joint is glued with bitumen mastic; for this you will need a burner. Strips of material are driven 10-15 cm upward over the entire area of the base of the house. Do not skip the side seams of the foundation.

The foundation is waterproofed with bitumen mastics by cutting off the water. The mixture is applied to the slab with paint brushes, rollers or spray. The complexity of this option lies in the concrete screed, which is made on a cement pad, after which a layer of mastic is applied. The sides and top are processed last.

Just as in the previous case, the rolled material in penetrating insulation is laid on a concrete screed. Once the slab is poured, a layer of waterproofing is applied to the top and side walls. It works as follows: a reaction occurs between the lime contained in the concrete and the active chemical elements in the waterproofing material. As a result, all the smallest pores become clogged for a long time. This method is the most effective.

Preparation for waterproofing

During the construction of a slab foundation, it is imperative to waterproof the joints between the elements. The seams are sealed with durable concrete, but it quickly absorbs moisture, so it is sealed with special polyurethane cords, coating treatment and sealants. Waterproofing under the foundation slab is also mandatory; it is done with liquid rubber.

Application of liquid rubber

Separately, it is worth saying a few words about filling with liquid rubber, which protects the foundation from moisture penetration. This method involves spraying a layer of molten rubber onto the surface of a bed of sand and gravel using a spray gun, onto which the foundation is later laid.

This method is quite expensive, but it promises complete isolation of the concrete base from groundwater, which has a positive effect on the durability of the building.

Waterproofing concrete joints

The most likely places for water leaks in structures made of waterproof concrete are expansion joints, junctions of vertical and horizontal structures, joints between prefabricated structural elements, and utility entries.

Expansion (temperature, sedimentation, anti-seismic and shrinkage) joints dividing the building into compartments are installed in the right places in the load-bearing and enclosing structures to prevent the appearance of random, unorganized cracks.

Technological (cold, working, structural) seams are made where the day's work on laying concrete has been completed.

Interruptions in concreting during the construction of structures, separate casting of the horizontal part and then the vertical part, or laying concrete on metal, stone, etc., for example, when concreting embedded parts and utility inputs, lead to the formation of so-called “cold joints.”

Cold joints in cast-in-place concrete structures are among the weak points in underground building structures and are the most common cause of water penetration.

Joints between prefabricated structural elements

Quite often, reinforced concrete blocks are used to build foundations or basements. In this case, the problem area is the joints between them.

The joints between structural elements are sealed using fine-grained cement-sand mortars. However, this creates cold (technological) seams, which in turn represent a potential place for water leakage.

To reduce the likelihood of leaks and increase the strength characteristics of butt joints, in recent times non-shrinking or slightly expanding dry cement-based building mixtures (see section “ Waterproofing mixtures” ) with high compressive strength (25-45 MPa) and water resistance ( W12-W16). However, it is advisable to additionally waterproof the butt joints formed using such mixtures with penetrating (penetrating) mineral compounds.

Pressure joints

Waterproofing of joints (when one reinforced concrete structural element is placed on another) is provided immediately before installation of concrete structures on concrete preparation.

To do this, it is recommended to apply a layer of mortar or dry powder of a penetrating cement-salt composition, a non-shrinking or expanding cement-based mortar onto the joint plane.

Strengthening waterproofing

In practice, it has been proven that strengthening flexible coating waterproofing along joints, abutments, mates and cold seams using reinforcing strips made of glass fiber materials (fiberglass, fiberglass) or geotextiles (density 100-150 g/m2) is an effective solution.

The use of reinforcing (strengthening) material ensures the distribution of tensile loads occurring in the waterproofing coating onto areas of the coating adjacent to the stressed zone and thereby preserves its integrity at the point of the load.

Materials for sealing seams

To seal the technological seam, the contact surface is coated with a penetrating material or a swelling cord (profile) is laid, which is also used to seal gaps.

Sealing of movable expansion joints is achieved by laying expansion joints (waterstops) made of rubber and various types of PVC.

Sealing seams: 1 – swelling cord; 2 – coating with penetrating material; 3 – waterstop

Features of the construction of the basement floor

Vertical waterproofing is performed on the outside of the basement walls; You can use adhesive or coating waterproofing, depending on design decisions and construction conditions. Penetrating waterproofing can be used on the internal surface of concrete structures.

The use of penetrating waterproofing (for example, Penetron) for monolithic reinforced concrete foundation structures is especially effective, and the obvious advantages are the following:

interacts well with the concrete mass in resistance to dampness and moisture;
eliminates even the most minor flaws in structures, due to which the strength properties of the material become 20% higher;
highly resistant to the influence of aggressive waters and solutions;
high resistance to mechanical stress;
increases frost resistance;
increases the service life of structures.

Naturally, such problems do not arise if there is no groundwater and there is no need to carefully carry out waterproofing measures. In this case, there is a greater range in choosing the type of foundations and materials - for example, installing a strip foundation from prefabricated foundation blocks (FBS).

In the case of a basement floor, as a rule, the level of the base of the foundation is not lower than the groundwater level. Sometimes it is very important to perform drainage.

To achieve a convenient vertical landing of the building, the level of the ground around the house can be increased by adding the required volume of soil in the adjacent areas of the construction site - in this case it will not be difficult to achieve the installation of the base of the foundations above the groundwater level.

The ground floor is operated at positive temperatures. Freezing of the soil under the floor and along the basement walls is not allowed, for which purpose the walls and floor of the basement are insulated. Extruded polystyrene foam can be used as insulation, the high strength and moisture resistance of which sets it apart from other insulating materials.

Effectively reducing or eliminating soil freezing is the installation of insulation under the blind area around the building.

In conclusion, we can note the additional advantages of a house with a basement:

tangible savings in space on a plot of land;
the optimal solution when building a house in an area with complex multi-level terrain;
the basement floor is an additional area of the house to accommodate premises such as a pantry with shelves for food, a laundry room, a bathhouse, a gym, a boiler room, etc.;
the ceiling of the ground floor can be used as an open terrace.

In the end, the ground floor, like a strong semi-underground structure, is structurally a convenient and reliable base for the subsequent construction of a house.

Injection with acrylate gels and polyurethane resins

The technology for injecting concrete and reinforced concrete structures allows you to introduce insulating materials inside the body of the floor slab or create an insulating layer behind its outer surface between the wall and the surface layer. Filling expansion joints, voids, cracks, and even concrete capillaries by injection with polyurethane resins and acrylate gels allows you to create a continuous monolithic barrier to the flow of water, as well as protect the room from negative manifestations of dampness, such as mold and mildew.

Waterproofing materials

The following products are used for waterproofing:

bitumen roll (roofing felt, roofing felt, stekloizol). They are cheap, but their service life is about 8 years, with the exception of glass insulation - lasts up to 20 years;
mastic mixtures made on an adhesive basis. Service life 10 years;
dry and liquid mixtures, last from a year to ten;
made of foamed polyethylene and polypropylene, depending on the manufacturer, lasts from 25 to 50 years.

In order for polyethylene foam insulation to serve its intended life, a plastic composition of mastic or plaster is applied on top of it to protect it from ultraviolet radiation.

Types of waterproofing

Based on the method of protecting concrete structures, a distinction is made between surface and penetrating waterproofing. Surface waterproofing, for example, coating or roll, is subject to constant dynamic loads due to water pressure. Over time, the protective layer peels off from the surface of the reinforced concrete structure, and moisture seeps into the gaps.

Penetrating waterproofing using the injection method is considered a more effective technology. Injection is the injection of active substances through holes drilled in concrete or masonry. Due to its low viscosity, the solution spreads through the pores throughout the entire volume of the treated area. The substance increases in volume, fills the cavities of the monolithic structure, and reliably blocks the access of water.

The advantages of the injection method of waterproofing include

formation of a strong protective frame;
all work is carried out from the inside;
adhesion of materials to any, including wet, substrates;
lack of excavation work;
long period of exposure - some substances do not lose their beneficial properties for 100 years or more.

Injection technology is used on the most complex objects - in subway tunnels, concrete tanks, swimming pools, and hydraulic structures. The injective method has no restrictions and is used on reinforced concrete structures of any size.

Waterproofing methods

The joints are sealed from the inside and outside. External waterproofing protection must be carried out during the construction of the structure. The moment of performing internal protection depends on the purpose of the structure. The need for internal protection arises if the external seal is significantly damaged. This leads to a decrease in the effectiveness of external sealing and entails a labor-intensive restoration process.

Popular waterproofing technologies involve the use of the following means:

swelling tapes and cords;
elastic polyvinyl chloride tapes;
waterproofing seals;
penetrating solutions;
sealants;
mastic;
bitumen backfills;
injection solutions.

The selection of technology is carried out at the time of project development. As a result of the measures taken, the ability to withstand operational impacts for a long time is strengthened. In this case, the tightness of the seam is the main point.

Stages of waterproofing joints at the construction stage of buildings:

installation of waterstops made of elastic material with high adhesion to concrete surfaces;
laying swelling cords;
layer-by-layer backfill of fine-grained crushed stone using bitumen filling.

Main structures requiring insulation:

floor slabs between pillars and strip foundations,
load-bearing foundation slabs,
ceiling tiles, etc.

They are made from different materials: wood, reinforced concrete, steel beams. However, sealing is carried out even in the case of concrete solutions. Particular attention must also be paid to protecting the seams between products. They need proper treatment and careful moisture-proof filling. Proper waterproofing of concrete slab joints prevents leaks from upper to lower levels and guarantees the absence of traces of moisture that negatively affect the condition and appearance of the structure itself.

Why do you need waterproofing of concrete floor slabs?

There can be many reasons for dampness:

poor seams;
low quality of cement used in the installation process;
worsening weather conditions;
for floors at the base of a building - capillary moistening of the structure with moisture from the soil.

Protection of slabs and seams between them can be done both during the construction of the house and during its operation. But the most reliable option is waterproofing concrete floor slabs at the construction stage.

There are many methods of protective treatment of slabs of such structures, but only a few of them are most often used.

Correction Methods

Naturally, it is always better to prevent a problem than to correct its consequences. But if the measures were not used correctly and freezing nevertheless began, it is necessary to begin correcting the mistakes as quickly as possible. There are a number of different ways to correct wall freezing problems.

Depends on circumstances and locations

Floor slab laying diagram.

The appearance of dampness and dark spots in the area of the outer floors usually occurs if the installation of attic floor insulation is insufficient or poor quality. First, deficiencies in the connections between the slabs are eliminated, which reduces the occurrence of water on the internal walls. Typically, expanded clay is used as insulation in attic floors. According to standards, for it to be productive it must be more than 30 cm.

Types of putties for sealing outside and inside

much attention is paid to external putty , since the following depends on its condition:

microclimate and heat preservation in the room;
resistance of slabs to unexpected seismic events;
no deformation of load-bearing walls and protection from water, insects, and temperature changes.

For sealing in apartment buildings they use:

cement mortar;
mastic;
sealants;
polyurethane foam used simultaneously with the sealant.

Each type of embedded material must be several times larger than the slot space , but should not extend beyond the wall structure. Therefore, it is laid in an even layer and trimmed with a spatula. The frozen expanded remains of the polyurethane foam are trimmed using a construction knife.

Mastic

This type of material is a plastic viscous mass, which is produced on the basis of natural substances with added fillers - resins, rubber, plasticizers, etc.

The industrial product is available in several varieties; it can be one-component or two-component. The polymer base of the mastic is characterized by good adhesion to various surfaces and has sufficient elasticity.

The most popular manufacturers of the material are companies:

CJSC "RASTRO" (St. Petersburg);
LLC TPK "MasticIzol" (Moscow);
“The latest technologies” (Novosibirsk).

The material has a long shelf life - up to 15 years, and is easy to work with. Mastic can be bitumen or polyurethane.

Based on the quality of hardening, it is divided into quickly hardening and non-hardening (for lubricating door and window openings and mechanisms).

Fast-hardening mastic is more suitable for seams. An important quality of the product is its water-repellent properties.

Each type is further divided into different types. For example, popular bitumen mastic is divided into rubber, polymer, emulsion and purely basic types. There is also cold and warm mastic, which is heated at the time of application. The polyurethane type is available in a lighter color than bitumen.

The mastic is sealed after thoroughly cleaning the surface and treating the seam with a primer solution, as well as fungicidal additives. Also, the mastic composition is used in a complex of layers for sealing - it is applied last so that it hardens and provides protection from the effects of water.

Sealant

The material is produced in a ready-made composition, in hermetically sealed packaging, and comes in :

one-component;
two-component.

Various types of sealants are especially good for expansion joints, and also as one of the layers of the “Warm Seam” method, the technology of which is based on the use of acrylic as well as polyurethane components.

Sealants can take the form of convenient cylinders or come in the form of “pistols” with a cone-shaped nozzle from which a certain amount of product is applied. But they can also be sold in buckets of 1-2 kg, from which they can be removed with a spatula and applied with a brush.

Step-by-step instruction

For interfloor ceilings that are located in areas with equal temperatures, two vapor barrier schemes are used. The first option is when it is installed on both sides of the heat insulator. It is allowed only if the internal air temperature between floors is equal and the following conditions are met:

The wooden elements for the partitions are dried using the chamber drying method and a dry heat insulator is installed.
Both vapor barrier films must be installed completely airtight.

These conditions are quite difficult to fulfill in practice, especially the first point, so protection is more often installed according to the second option - a vapor-proof layer is installed on one side of the heat insulator under the rough ceiling , and on the other side a vapor-permeable hydro-windproof film is installed.

The procedure for performing work on floors in a wooden house:

Fix 40x40 bars along the bottom of the beams with 75 mm self-tapping screws, at intervals of 50 cm.
On top of the beams, a roll of 20 mm boards is attached, laid across the beams and with a gap of 10 mm from the edge of the board and beam on each side.
Hem the vapor barrier with the heat shield facing down.
Carefully seal the joints with metallized tape.
Mineral wool 100 mm thick or other sizes are installed on top of the roll-up according to the calculation of the required insulation.
The heat insulation layer is covered with a vapor-permeable membrane. In order to prevent the penetration of insulation fibers through underground ventilation ducts into the room.
Fastening is done with a construction stapler.
Joists are placed on the beams under the subfloor with a ventilation gap above the insulation of at least 40 mm.
The system is closed with MDF sheets no thinner than 22 mm and an external covering is arranged.
A ventilation system is being created for the underground space.

Thus, even if moisture gets into the ceiling, it will be able to leave it through the vapor-permeable film and further into the air gap, after which it will be removed by house ventilation systems.

Waterproofing walls in an apartment

If you notice that moisture is appearing on the walls of your apartment, you shouldn’t blame it all on the poor waterproofing. In fact, a similar phenomenon can occur, for example, in corner rooms or rooms adjacent to the landing.

The cause of humidification is the condensation of warm air vapor inside the apartment on a cold section of the stove. In order for the walls to stop “crying”, you will have to restore or improve the insulation of your home.

If the walls get wet due to a violation of the waterproofing of the seams between concrete slabs, the seam will have to be repaired not only inside the room, but also outside the building. If the apartment is located on a high floor, it will not be possible to carry out external work yourself.

They must be carried out by workers of special construction organizations, who climb to the problem area of the facade in a special cradle, open the seam and seal it.

You can only seal the joints between the wall and the ceiling indoors on your own by gluing the seam in an accessible place with some kind of sealant. To do this, you can use Guerlain tape sealant made from synthetic rubber.

This material is successfully used for sealing joints, roofing seams and when installing windows. You can also use “Abris” SL-T butyl rubber tape with a width of 50, 70, 100 mm, which can be double-sided, metallized, etc.

Before you start insulating the walls, you need to find out whether leakage occurs at the joints (seams) of the slabs or whether the entire wall gets wet due to the presence of microcracks. In the first case, the joints should be treated, and in the second, the entire walls.

Walls covered with microcracks should be treated with one of the penetrating waterproofing compounds, which will increase the performance characteristics of concrete. It is also possible to carry out internal coating waterproofing of the wall with a composition based on cement, polymer-cement or polymer.

Among the materials that allow for external work, we recommend the organosilicon water repellent "Aquastop-K", which is used to increase the moisture resistance of brick, slate, concrete and aerated concrete, stone, gypsum and other materials that absorb moisture.

This waterproofing material not only increases the moisture resistance of the walls, but also retains at least 95% of the original vapor permeability and practically does not change their appearance, which is very important when repairing facades. Aquastop-K is usually not used for interior work.

Water-based hydrophobic liquids GSK-1 and solvent-based GSK-2 are widely used. The latter can be used even at an air temperature of -5 C.

Also suitable for waterproofing walls is the elastic polymer-cement waterproofing dry mixture “Ceresit CR166” made in Germany. It can be used for interior and exterior work on concrete, brick and other permeable materials.

This material forms a common crystal lattice with the base, eliminating the possibility of peeling, and thereby significantly increases the service life of the walls.

For plastering waterproofing of walls, the Kalmatron-Economy material is used. It is applied to the surface of concrete, brick, cinder block and other building structures. Thanks to this material, the waterproofness of the walls is restored, it also gives them strength and frost resistance. The technology for using this composition is quite simple and accessible.

Conservation of a construction site

For whatever reasons, the construction of the facility was suspended in the winter, it is necessary to carry out a set of necessary work to prepare for the conservation of the facility itself and the materials brought for construction.

Snow and frost can greatly damage the foundation

There are several reasons that can cause damage to prepared building materials and erected structures:

Atmospheric precipitation - water from rainfall is absorbed into materials and accumulates in the cavities of building structures. With the onset of the first frosts, the water freezes and expands significantly, which can cause destruction of building structures and damage to materials.
Low temperatures can cause deterioration in the properties of some building materials, which lose their properties and become very brittle. To prevent damage to material resources, it is very important to cover them correctly.
Water and frost cause a phenomenon called soil heaving - frozen wet soil begins to push foundation structures to the surface of the earth. Shallow foundations suffer greatly from this phenomenon.
Excessive snow load in winter can cause the collapse of building structures that are not designed to withstand a load of such force.
The last reason in favor of conservation is not related to natural phenomena or the design features of the building. At a site unprepared for wintering, there is a danger of theft of materials that are not guarded by anyone during the winter period.

Recommendations for materials for waterproofing joints

Work on waterproofing seams is aimed at reducing the loss of thermal energy and protecting premises for various purposes from noise, dust, drafts, as well as from slow but sure destruction.

Such work can be carried out in new buildings and in already used buildings and premises.

Innovative compounds that are used for waterproofing work are made on the basis of foamed polyolefin and polyethylene and can last up to 50 years.

Waterproofing materials

mastic mixtures, which are produced on an adhesive basis, with a service life of 10 years;
bitumen-roofing felt materials are affordable in price, but have a short service life, about 8 years (roofing felt, glass, roofing felt), the exception in this series is glass insulation, which can last up to 20 years;
materials based on foamed polyethylene and polyolefin with a service life of 25 to 50 years, depending on the manufacturer of the composition;
waterproofing mixtures are dry and liquid , which last from one year to ten years.