Waterproofing a septic tank of concrete rings: methods and materials

Underground concrete structures need protection from the aggressive environment in which they have to work. Local sewage treatment plants are not an exception, besides aggravated by the possibility of damaging the environment in the event of a leak. You must admit that such a catastrophe, even if it is of local significance, must be prevented.

Properly made waterproofing of a septic tank from concrete rings will prevent the occurrence of corrosion of the structure. Eliminates the likelihood of direct communication of content with surrounding soils. The water-repellent material will protect the concrete and the compounds used to treat the joints from erosion.

The article introduces the types of waterproofing used in improving the stability of concrete. We described in detail the technology of protection performance, gave an assessment of the effectiveness of the options. Faster get settled into the topic will help photo-collection and video instruction.

Purpose and types of waterproofing septic tank

In concrete, under the influence of moisture, leaching of lime is observed, which manifests itself by the appearance of stalactites and growths on the surface of rings. The material is destroyed by the magnesium salts contained in groundwater.

By reacting with lime, they create a compound that dissolves in water, calcium sulfoaluminate, which water washes away the concrete from the body, destroying it.

Carbon dioxide, also present in groundwater, triggers destructive processes in concrete, reacting with calcium hydroxide.

Water entering microcracks and pores turns into ice as the temperature decreases. The increase in its volume leads to fractures and large cracks in the already porous structure of the material. Biological corrosion of concrete is caused by microorganisms living in water.

Salt solutions, in contact with metal reinforcement located in the body of concrete, cause electrochemical corrosion of steel. Due to its gradual destruction, the strength characteristics of the product are reduced, and then the structure becomes completely unusable. Replacing concrete rings involves many difficulties, and sometimes is simply impossible.

If you do not protect the septic tank from the effects of destructive factors, the dirty water will fall into the ground, and infect it with microorganisms. An unpleasant smell will appear on the site, and representatives of the supervisory authorities will become your frequent guests.

All these reasons are enough to allocate funds and time to perform high-quality waterproofing of the septic tank, thereby avoiding problems with frequent and time-consuming repairs.

Particular attention should be paid to waterproofing the bottom of the first well at its junction with the lower ring. The foundation is concreted using mesh as reinforcement.

To increase the strength of concrete rings outside and inside there are many materials.

The most commonly used are:

1. Sprayed compounds. Rings process them outside using special equipment.
2. Injection protection. It happens on an epoxy, mineral or polyurethane basis. For septic tanks it is used in extreme cases, because it is expensive.
3. Coating compositions. Bituminous and bitumen containing. These are film-forming mixtures that create a thin, water-impermeable layer when applied in several layers.
4. Rolled materials. Used for waterproofing waterproofing. They are stabilized bitumen or bitumen-polymer mastic applied to a fabric base of geotextile or fiberglass.
5. Penetrating formulations. Insoluble crystalline hydrates are formed in the thickness of the concrete, creating a reliable hydro-barrier from the side of application to the penetration depth declared by the manufacturer of the means.

Many different waterproofing materials come to the construction market, it’s not so easy to understand them and choose the one you need.

According to the criteria of durability and reliability, each type of waterproofing is different from each other. So, bitumen protection after a few years begins to crack, and mastic has a longer service life.

For more information about the options for waterproofing device for sewer manholes you find here.

Sprayed water barrier

This type of insulation allows you to create a monolithic seamless layer. Water repellent emulsions are sprayed onto the surface of concrete rings under high pressure. The composition penetrates into splits, cracks, pores and completely fills them, blocking drains in a confined space.

The composition for spraying has a polymer composite, water and fillers such as talc, calcium carbonate, titanium dioxide, barium sulfate.

The use of waterproofing applied by spraying provides many advantages:

1. The speed of execution.
2. Excellent adhesion to concrete.
3. Fast freeze.
4. Durability. Operated up to 20 years without loss of initial effectiveness.
5. Resistant to rapid temperature changes.

Sprayed waterproofing significantly improves the performance of the septic tank, thereby preventing the ingress of sewage into the surrounding soil structure.

This type of waterproofing provides adhesion to the surface of concrete rings at the molecular level. It can be applied over the old layer by spraying. The main thing is to remove before this excess moisture from the surface.

Coating compositions to protect the septic tank

Compared with other waterproofing technologies, the advantage of using coating materials is that they can be applied to surfaces with any geometry. No special devices and mechanisms are required.

Classification of water repellent materials

There are 4 groups of coating compositions, differing in the basis, which is used as:

• bitumen;
• cement;
• polymers.

By the 4th group include mastics, containing in its composition sealants. Regardless of the base, the coating waterproofing fills the smallest cracks, eliminates defects and makes the surface monolithic.

Some brands of bitumen-polymer mastic contain volatile toxic compounds. Sometimes they provoke disorders of the nervous system, lead to poisoning, therefore, you need to work only using protective equipment - respirator, gloves, and a special robe.

If the groundwater is at a great depth, then the isolation of the lower ring of the septic tank is increased. If they lie high, then the top of the structure should be sealed.

Bitumen-polymer mastic contains polymer additives and latex, due to the presence of which the characteristics of the material are changing for the better. When applied to the surface, an elastic, very durable layer is created, which retains its qualities at low temperatures. But in order for the bitumen-polymer composition to work, it must be applied in several layers.

It is relatively inexpensive mastic, you can apply it yourself, and if leaks appear somewhere, it is easy to restore the layer.

In addition, compared with other waterproofing technologies, the advantage of using coating materials is that they can be applied to surfaces with any geometry.

No special devices and mechanisms are required. Distinguish mastic with a bitumen base and with additives in the form of polymers for cold and hot application.

The mastic for applying the hot method is first heated to 160 degrees C, so that the bitumen goes into a plastic state. After they cover the surface of concrete rings. Cold formulations are diluted with a solvent that evaporates after the insulating layer hardens.

Single- and 2-component mastics. Bitumen, the polymer is present in their composition is mandatory, and additives that provide individual properties are different. Depending on the second component, the compositions are called: bitumen-latex, bitumen-rubber, bitumen-oil, bitumen-polyurethane.

Polyurethane and rubber make the material particularly elastic. The coating is well stretched, not forming cracks. The mixture with rubber is applied in a cold way. It has antiseptic properties and high heat resistance.

The surface covered with the mixture with oil ingredients does not harden. It is adhesive, well resists the aggressive influence of groundwater and soil, does not crack, endures both frost and -50 degrees C, and high temperatures.

Coating application rules

Waterproofing is applied after sealing the inter-ring seams and places where the pipes go into the septic tank.

The process itself consists of 5 consecutive stages:

1. Cleaning the surface from dirt, identifying defects, cracks and removing them with the use of sealants or putty.
2. Application of a bituminous primer as a primer. It is first prepared according to the manufacturer’s instructions, then covered with a construction brush. The bituminous primer can also be made with your own hands, for which you take gasoline or engine oil, heat and add crushed clean construction bitumen. Stirring the mixture continues to heat to 200 degrees C, after which the primer is ready for use. Apply the first layer, and after it dries - the second.
3. Leave everything for 24 hours. During this time, the primer will dry completely and its fine particles will penetrate deep into the concrete.
4. Apply with a construction brush mastic, after carefully mixing the composition. If the mixture is too thick, it is diluted with any organic solvent. After completing the first layer, take time to dry it and repeat the procedure.
5. Check the quality of the applied layer after drying. When flaws are found, the surface is treated again and left for 2-3 days to dry.

Bitumen mastic is much cheaper than bitumen materials with polymer additives. It adheres well with concrete wall septic tankIt has good water repellency and is resistant to chemicals.

Poor bitumen mastic makes negative temperatures, the coating becomes brittle, covered with micro-cracks. Enough of this waterproofing for 5 years, a maximum of 7.

Some brands of bitumen-polymer mastics contain volatile toxic compounds. Sometimes they provoke disorders of the nervous system, lead to poisoning, therefore, you need to work only using protective equipment - respirator, gloves, and a special robe.

Clay lock device

Good results are obtained by processing the rings with bitumen mastic followed by a clay castle. This means that the space between the concrete rings and the ground is filled with clay without any impurities. It is necessary so that after the snow melts or heavy rain the water does not fall into the septic tank.

It is recommended not to do it immediately, but after the ground has settled and compacted. The castle, made earlier, will be destroyed when the soil subsides. Clay is poured in small layers, each time carefully tamped. Over the entire surface of the material should fit. The slightest voids are not allowed, otherwise the work done will not give a result.

Rolled waterproofing surface septic tank

This type of material is used to waterproof the outer surface of reinforced concrete rings. First, to improve adhesion, the surface of the rings is primed using Betokontakt-type compounds.

When the layer dries, visible defects are eliminated on the walls of the septic tank, filling cavities and cavities with a solution including cement, sand and PVA glue. Between the rings close up the seams. When the repair patches dry up, they are primed.

To fix the rolled material on the surface of the rings, the walls are coated with tar or bitumen mastic, and then waterproofing is glued. It is not enough one layer, it is practiced to do a layer 3-4. In the end they take mastic and put it on the seams between the strips.

Pressure plaster

Apply also plaster under pressure to an internal and external waterproofing. Non-shrink waterproof cement is fed under high pressure generated by compressed air. The sealing layer is uniform and dense.

The use of this method is not always justified due to the considerable financial costs. To implement it, it is necessary to have a special device, the so-called "cement gun". Work is carried out at a temperature of at least +5 degrees C, 2 layers are laid, the thickness of each is from 5 to 10 mm.

To apply the next layer, you have to wait until the previous one is fully grasped, and this sometimes takes up to 2 weeks. To prevent cracking of cement on a hot day, its every 3.5 hours. moisturize. In cool weather, the interval is increased to 12 hours.

Waterproofing penetrating or capillary

This type of waterproofing is the most reliable. The materials, after being applied to the concrete surface, penetrate into the pores, crystallize, fill all the voids. Threadlike crystals are embedded in the structure of concrete, clogging microcracks and become one with its body. They do not impair the air permeability of the surface, but, sealing its structure, they do not allow water to pass through.

Crystal hydrates do not decompose and are not washed out from concrete, therefore such protection of a septic tank serves for a long time. The layer on the surface of the rings only fixes, and for some time holds the active chemical components that play a major role in creating high-quality waterproofing design.

Some manufacturers claim that once all chemical processes are completed, the layer can be removed.

The duration of crystallization and the depth of penetration of the insulating material into the thickness of concrete are influenced by the degree of porosity and the moisture content of the septic tank rings. At high humidity parameters, crystals are formed faster, and as this index decreases, the process slows down. In concrete surfaces treated in this way, the microcracks themselves are tightened.

The application of penetrating waterproofing is preceded by a thorough surface treatment. It is completely cleaned using special chemical solutions or mechanical method.

When the result is a flat surface, it is saturated with moisture, pouring water from a hose under high pressure. The active ingredients of the waterproofing compound penetrate the same depth as water.

Processing begins with seams. It is better to do this during the installation of the rings. They are placed on a layer of cement mortar, then treated with a penetrating mixture. Further, the mixture is applied to the entire surface, strictly adhering to the manufacturer's instructions, otherwise the waterproofing layer will not meet the stated requirements.

The mixture is prepared in small portions. For mixing it with water used electric drill, working at low speeds and equipped with a spiral nozzle. The composition is applied to the surface of the rings using a spray gun, roller or paint brush. You need at least 2 layers with an application interval of 1.5 to 3.5 hours.

The second treatment begins when the first layer has not yet had time to dry completely. It should be a coating with a total thickness of 1.5-2 mm. Material takes a lot - about 1 kg per 1 square. m

For penetrating waterproofing used such compositions:

1. "Lakhta". Inexpensive cement-based dry mix.
2. Kalmatron. The composition includes Portland cement, sand, patented active reagents.
3. "Hydro S". The waterproofing covering on the basis of mineral raw materials.
4. "Penetron". Penetrating mixture that creates a barrier that prevents capillary suction of fluid.

If to process a septic tank from the outside and inside, then as a result you will have a durable hermetic construction with a homogeneous structure.

Materials for sealing the interring seams

The seams between reinforced concrete rings are the weak link of the septic tank. Most often, the first leaks appear here. For this reason, their sealing is necessary. As an insulator used reinforcing fabric, rubber band seals, rubber pads with bentonite granules, polymer cement in combination with jute or hemp rope.

In the first and second cases, the insulation is effective, but it is expensive, and the reinforcing fabric must also be irradiated with ultraviolet light. Rubber pads are cheaper, they fill the gap, creating a plastic layer. Pick them up, focusing on the thickness of the walls of concrete rings.

Manufacturing companies producing penetrating waterproofing, produce auxiliary mixtures. They close up not only the seams between the rings, but also seal the pipe inlets, repair wide cracks. They also include high-quality cement, silica sand of the smallest fraction, chemically active additives. They have excellent adhesion to concrete.

To seal the seam or crack, along them, the grinder and the perforator make a strobe to a depth of 2.5-3 cm and to the same width. It is cleaned from dust, small particles, moistened with water, and a primer is applied. When the primer composition dries, fill the strobe with an auxiliary composition. After the seam and part of the surface around it is treated with the main waterproofing mixture.

Among the additional materials there is a group designed to eliminate pressure leaks. They are distinguished by rapid setting with simultaneous expansion. Around the leak just clear the surface, then a punch do a sample resembling the shape of "dovetail".

A cork is formed from the mixture, with dimensions slightly exceeding the dimensions of the sample, with an effort is pressed into the leakage place, and is held until fully set.

When the water stops flowing, the cavity is primed with the basic composition, completely filled with an additional solution, allowed to dry, and moisturize. Next, apply a 2-layer coating using the main waterproofing mixture. With respect to technology, the likelihood of re-occurrence of a leak is 0.

Popular auxiliary formulations include:

1. "Waterplag". Hydraulic valve is used to eliminate a weak leak. Grabs within 3 min.
2. "Peneplag". The fast-setting mixture stops the most intense flow in 40 seconds.
3. AQUAFIX. Hydraulic block, freezing under the influence of moisture in a short time, therefore, is well suited in the case when it is necessary to eliminate the leak.
4. "Penekrit". Used for sealing joints, pipe entry points in the septic tank.
5. MEGACRET-40 - repair composition based on cement with the inclusion of polymers. Suitable for sealing intercircular joints, and for sealing cracks. It has excellent adhesion to the concrete surface, is easy to apply, does not shrink.

All manufacturers declare that their mixtures have a unique patented composition. In fact, their characteristics, like the methods of creating a protective layer, are about the same. The final result is influenced by the fact that the surface and the waterproofing composition are so well prepared.

Conclusions and useful video on the topic

Here you will see how to eliminate active leaks:

Using any option of waterproofing septic tank, remember that the guarantee of obtaining high-quality durable coating is accurate adherence to technology. Do not neglect the recommendations of the manufacturers, concerning both the preparation of mixtures and their application.

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