How to waterproof concrete rings

Good afternoon Tell me, what is the best way to waterproof concrete rings? Do they need to be pre-dried? And is it possible to do this yourself?

Hello.

It’s a pity that you didn’t indicate what type of structure the concrete rings are used for and what it is. The answer would be shorter and more precise. Because, for example, different requirements are imposed for insulating a water well with drinking water and a septic tank with fecal wastewater. Since we don’t know anything about your rings, we will have to limit ourselves to considering the basic principles of waterproofing underground structures made of prefabricated reinforced concrete elements.

Types of waterproofing materials

For waterproofing underground structures, we recommend using three types of materials: cement-polymer compositions, bitumen-polymer and polymer insulation:

• Cement-polymer mixtures

They are inexpensive, have excellent adhesion (the ability to adhere to a surface) to concrete, and are very durable. Moreover, the reliability of penetrating cement waterproofing only increases with time, and its service life is at least 40 years. The application method is extremely simple: just apply the composition to the mineral surface with a brush or spatula in two or three layers.

It is not difficult to apply cement-polymer waterproofing with your own hands; you do not need to have any special qualifications or special tools

There is no need to dry the concrete; on the contrary, you need to moisten it. Work can be carried out in almost any weather at temperatures above +5 ºС. Concrete products should be pre-prepared: cleaned of dirt; it is more convenient to do this using a high-pressure washer. Grind sinks and uneven areas with a solution or repair compound; you can use frost-resistant tile adhesive. Cement-polymer insulation has another very useful property: without allowing water to pass through, it is capable of passing water vapor, which is important for maintained wells. A significant portion of cement-polymer mixtures are suitable for treating drinking water tanks.

The choice of brands of cement-polymer compositions is quite wide. Among the domestic ones, we can recommend the compositions Penetron (http://penetron.ru), among the foreign ones - Ceresit products (http://www.ceresit.ru/products/waterproofing_materials), which are mostly produced in the Russian Federation, EurAsEC countries and Ukraine under strict control of German technologists.

It must be taken into account that standard inexpensive cement-polymer compositions are very resistant to abrasion, but are inelastic. If a crack occurs in a concrete structure (as a rule, this occurs at the joints between the rings), the integrity of the waterproofing coating will also be compromised. If the structure is unstable, there is a risk of cracks, or they have already appeared, the problem can be solved using a special elastic tape for sealing seams (for example, CeresitCL 152) or a two-component composition with increased elasticity (CeresitCR 166), applying it in two layers with intermediate reinforcement fiberglass mesh. True, these materials can no longer be called cheap.

Elastic seam tapes are most often used to seal the joint between vertical and horizontal surfaces, but can be used for any problematic seams or cracks

• Bitumen-polymer waterproofing

We do not recommend using bituminous materials (roofing felt, mastics) without polymer additives; they are cheap, but their service life is only 5-15 years. Polymer-bitumen waterproofing can be coated (mastic) and built-up (rolls hot glued to mastic. The latter is much more expensive than coating, more difficult to install, and requires special tools.

In order to fuse rolled insulation with high quality, you need to have a special gas burner; a more affordable blowtorch will not give the desired result

However, fused insulation is more reliable and durable, with a service life of up to 30 years. The rolled material tends to stretch a little; small cracks in the concrete structure are not harmful to the waterproofing coating.

Despite excellent waterproofing properties, bitumen-polymer materials have mediocre adhesion to concrete. Applied to a clean, leveled and dry surface, they will remain securely in place only as long as the moisture content of the concrete does not become too high. If the base is wet, capillary moisture will gradually begin to tear the bitumen material away from the mineral surface; if it becomes very wet, the insulation may come off completely. When roll waterproofing is glued to concrete rings from the outside and pressed with soil, it still can’t get away, even if it moves away from the surface. But if it is applied from inside the well, and the concrete is often and abundantly moistened, over time it may come off in places and stop performing its functions, or even the rolls will completely peel off and fall to the bottom of the structure in a useless heap.

• Polymer insulation

It is similar in properties to bitumen, but significantly exceeds it in elasticity, which is why polymer roll membranes and mastics are recommended for use on deformable surfaces in which unstable cracks may appear. The service life is also significant - 40 years.

“Liquid rubber” (polymer mastic) is the most elastic waterproofing material

Unfortunately, the high price limits the use of polymer insulation.

Bitumen-polymer and polymer waterproofing produced in Russia by Technonikol (http://www.tn.ru/catalogue/?bokm_id=rullon_materials) has a good price/quality ratio.

Pay special attention to sealing the seams between the rings

Concrete compacted in a factory almost does not allow water to pass through; we can only talk about capillary penetration if the products are of high quality. Practice shows that in wells assembled from standard concrete rings, leaks occur mainly due to leaky seams. It is important even at the installation stage to ensure that the seams between the rings are filled with mortar. It is mixed using Portland cement and sifted sand in a ratio of 1:3. The result will be much better if you add Penetron Admix to the mixture, it will give the solution waterproofing properties.

Careful sealing of seams is an indispensable condition for high-quality waterproofing

Drinking water well insulation

For waterproofing drinking water tanks, only cement-polymer compositions should be used, the packaging of which clearly indicates this. Bitumen - not possible. Wells, as a rule, have great depth and are built by the method of sequential lowering of reinforced concrete rings with parallel excavation of soil. This technology gives two limitations: waterproofing can only be done from the inside; installation sealing of seams between the rings often leaves much to be desired due to small displacements during the settling process. If there is concern about the quality of the joint seal, the mortar should be removed from the seam to a depth of 25-50 mm; weak fragments that crumble and crumble when hit with a hammer should be removed completely. Carefully fill the seams with a special non-shrinking waterproofing cement-polymer mixture (for example, Penecrit).

When filling a seam to a great depth, you will have to do it not in one, but in two or three steps

If the well is located in very wet soils and you need to eliminate an active leak (water erodes the usual mixture for joints), you can seal the leak with a quick-setting cement-polymer hydraulic seal (“Peneplug”). Then treat the entire inner surface of the well with penetrating insulation (for example, Penetron) and keep it moist for two weeks.

No matter how carefully you waterproof the well, do not neglect cheap and effective methods of drainage: build a blind area over a clay castle.

A castle made of rich clay will drain melt and rain water and prevent it from leaking along the walls of the well

Septic tank insulation

If we are talking about a multi-chamber septic tank for wastewater, there is no need to isolate the last absorption well in the chain. On the contrary, water should flow from it into the ground in maximum quantities. And there is no particular need for waterproofing the first sections of the septic tank, which are not located below the groundwater level. Unless this is required by environmental protection. It's not a big deal for the environment if a little waste seeps into the ground; it is an excellent biofilter. What is really needed is to prevent large quantities of melt and rainwater from entering the structure. To do this, it is enough to carefully seal the seams between the rings, and do not forget about the cover, the head of the well, and the pipe entries.

When waterproofing a septic tank, pay special attention to sealing the seams between prefabricated structural elements

If waterproofing is still done, the material is selected depending on whether it is an external or internal surface. When constructing a well using the sequential lowering method, insulation is performed from the inside and only with the help of cement-polymer compositions; bitumen ones will not hold well. If the hole was dug by an excavator, there is enough space to waterproof the outside. In this case, you can use any material. It is convenient to fuse a roll of bitumen-polymer coating onto the ring before installation, when it is located on the surface of the ground. And having installed it in place, glue only the joint between the rings.

Bituminous insulation is only suitable for use outside the structure

Do not stick rolled material onto an uneven surface. The head of the septic tank, lined with concrete bricks, is coated with a polymer-cement composition

Process well insulation

For a dry well located in wet soil, waterproofing is required. The application technology is the same as for a septic tank. If possible, it is better to insulate the structure from the outside. Not only the walls, but also the bottom of the well must be protected from moisture. For external insulation, a bitumen-polymer or cement-polymer coating should be applied to the concrete bottom slab before installing the rings. You should also pay attention to the height of the hatch relative to the ground: when it rains, water should not flood it.

If possible, waterproofing can be done on both sides, this will increase reliability. In the photo - a serviced service well for communication input, the outer and inner surfaces are treated with an inexpensive cement-polymer composition