How and what is the waterproofing sewer wells
One of the most common ways to build a sewage system in a private house is the construction of a concrete septic tank. Moreover, not everyone is wondering about its tightness.
And in vain, after all correctly executed waterproofing of sewer wells not only will prolong the term of their operation, but also will protect soil from pollution.
Why waterproof the sewer well?
A serious mistake is made by those who believe that it is possible to neglect the work associated with the sealing of the sewer well.
At best, there will be severe pollution of groundwater, and at worst, a septic tank of concrete rings will collapse in a few years.
There are several reasons due to which the waterproofing of the well cannot be neglected, it is:
- Corrosion reinforcing component of reinforced concrete rings.As a result of the formation of foci of rust on the reinforcement elements, the bearing capacity of the well shaft, which is constantly subjected to the pressure of the soil enclosing it, is significantly reduced.
- The weakening of the concrete walls of the mine.Wastewater and groundwater contain chemically aggressive substances that adversely affect the structure of concrete. Over time, under their action, shells and cracks are formed, leading to the destruction of concrete.
- The probability of infiltration of wastewater.The walls of the concrete mine with caverns and cracks will not be able to prevent the infiltration of wastewater into the surrounding soil. As a result, it will lead to a critical change in the ecological balance.
- Depressurization of joints.The concrete that has absorbed water during the frosty period will slightly increase in size. Imperceptible visually "shifts" of concrete rings will become a serious threat to the joints of the mine assembled from them.
- Concrete destruction. The freezing of the binder component of the concrete stone at sub-zero temperatures, especially in the zone of seasonal freezing of the soil, leads to a rapid disruption of bonds in the monolithic array. For this reason, the well will serve two to three times less than the allotted time.
If the protective properties of waterproofing everything is clear, then there is another important reason for sealing the sewer well. We are talking about floods and groundwater, the level of which during the period of active snowmelt and heavy rain becomes significantly higher.
Flood and groundwater can cause premature filling of the well, because concrete without waterproofing is able to pass water. As a result, you will have to carry out pumping using special equipment.
Works on isolation of sewer wells can be divided into two main types:
- Internal waterproofing;
- Exterior waterproofing.
It is recommended to perform both internal and external waterproofing at the same time, which will allow the maximum protection of the walls of the well against erosion, and the soil and groundwater - from pollution.
The main task of such waterproofing is to minimize or completely eliminate the contact of the external walls of the septic tank with groundwater.
It is best to perform the work at the stage of construction of the well. If this is not done on time, then you will have to perform a significant amount of earthworks.
Waterproofing with bitumen materials
Bitumen mastics and bitumen rolled materials are used for external waterproofing:
- On the cleaned and prepared surface it is necessary to apply the composition of 3 parts of gasoline and 1 part of bitumen. Apply the mixture using a compressor by spraying, but you can restrict yourself with a regular brush.
- For maximum sealing of seams, they should be glued with a rubber-concrete tape.
- After the first layer of primer dries, it is necessary to prepare the concrete rings - seal the chipped and hollows to obtain a smooth surface. To fill the sinks, it is best to use a mixture of PVA glue with a cement-sand mortar in a ratio of 1 to 5, but you can restrict yourself to the usual cement mortar.
- After the cement dries, you need to apply another 1 layer of soil from a bitumen-gasoline mixture, but in a ratio of 1 to 1.
- The next step is the application of mastic, it is better to use tar mastic, as the bitumen mastic easily exfoliates. You can also apply coating bitumen mastic with polymer additives.
- It remains to apply 3-4 layers of rolled materials (roofing material), carefully sizing the joints.
- Upon completion of the work it is necessary to fill up the soil, if necessary, arrange a clay castle and a concrete blind area.
The main advantage of the waterproofing of the well bitumen materials are the simplicity of the work and cheap material. It should clearly adhere to the technology of work, as a violation of the proportion of bitumen-gasoline mixture can cause premature destruction of the protective layer.
Waterproofing penetrating impregnation
Waterproofing penetrating action is a good alternative to bituminous materials.However, for its use requires more thorough preparation of the concrete surface with the elimination of all irregularities and grinding. At the same time, sanding is best done by sandblasting, which will maximize the opening of the pores of the concrete.
After grinding the concrete primer is not performed. Before applying deep penetration waterproofing, it is necessary to wet the treated surface well. It is best to give preference to the proven primer "Penetron", "Kalmatron", "KTTron", but you can restrict yourself to cheaper counterparts like "Elakor-PU".
Waterproofing should be applied with a sponge or a brush with a stiff brush. The drying time of the composition is three days. At the same time, during the drying process, it is necessary to moisten the surface to avoid cracking, and in hot weather it is necessary to carry out moistening every 3-4 hours.
After the first layer has dried, another layer of waterproofing should be applied. Smears can be done with a brush or spatula, they should be directed perpendicular to the previous strokes.It is important to ensure that the surface is not subjected to mechanical damage and drying during the freezing period.
Plaster under pressure (shotcrete)
When cementing a concrete with concrete, the surface of concrete rings does not need preliminary preparation. With the help of a cement gun, providing a minimum pressure of 4 atmospheres, a layer of cement 5-10 mm thick is applied. High pressure provides maximum compaction of cement and a decrease in its porosity.
Cement coating requires periodic wetting (3-4 hours in hot weather and 10-12 hours in normal conditions). After 10-12 days, you need to repeat the gunning and apply another layer of cement.
Clay insulation device
If it is not possible to isolate the upper rings of a sewer well by expensive means, ordinary wrinkled clay will do. The principle of protection of concrete walls is similar to the arrangement of wells with drinking water clay locks. Only a layer of clay is placed in a narrower trench around the mine, because it is not necessary to protect the drains from precipitation and flood waters.
Clay castle is best done in the spring in warm, dry weather. You can use the clay that was extracted during the construction of the well. At the same time, it is necessary to remove sand impurities and remnants of stones.
At the first stage, it is necessary to free up the space around the rings with a thickness of 20-25 cm to a depth of about 2 m. Initially, the resulting gap must be filled with moist and oily clay, carefully tamping it down.
Next, you need to remove a layer of earth 30 cm thick within a radius of 1-2 m from the ring wall. The resulting space should be filled in layers of clay, laying it in layers of 8-10 cm. Each of the stacked layers must be well compacted. The resulting clay castle will minimize the contact of the external walls of the well with flood waters and precipitation.
After a couple of years, when the ground is as thick as possible and set, you can begin to build a concrete pavement. For this you will need to install the formwork, make filling cement-crushed stone mixture in a ratio of 1 to 10.The thickness of the backfill should be 0.1-0.15 m, it must be well compacted. It remains to prepare the concrete and fill.
The following materials can be used for internal waterproofing:
- Cement putty;
- Bituminous gasoline mastic or molten bitumen;
- Cement-polymer composition;
- Bitumen-polymer mixture;
- Polymer waterproofing.
The internal waterproofing of a sewer well can be made shortly before its operation.
Before carrying out waterproofing works, the well must be dried. The surface of the concrete should be cleaned of dirt and dust, if necessary - to make grinding. Cracks, joints and gaps need to be expanded to 20-30 mm, cleaned with a brush on metal and sealed with a cement-polymer mixture.
Waterproofing cement mixture
For the waterproofing of a septic tank, it is best to use a ready-mixed mixture, which is sufficient to be diluted with water in accordance with the instructions. The resulting composition should be applied with a spatula 2-3 times so that a layer of 6-8 mm thick is formed.
After applying the last layer, the surface should be moistened and the well closed with a lid.Depending on the temperature, the drying time of the waterproofing layer may be 4-5 days. During this time, it is necessary to open the well 3-4 times a day and moisten the inner surface. The service life of cement insulation is up to 15 years.
Most often, the cement mixture is used to isolate the joints before applying the finishing waterproofing.
The use of bitumen-gasoline painting
The works are performed in the same way as with the device of similar external waterproofing. The mixture is applied in three layers, the time of solidification of each of the layers is about 12 hours. This type of waterproofing is not durable, the service life does not exceed 10 years.
If instead of bitumen-gasoline paint put two layers of bitumen mastic and weld the roll insulation, then the service life can be tripled. It is necessary to work as carefully as possible and to ensure the ventilation of the well, so surfacing inside is associated with certain risks.
Waterproofing cement-polymer composition
Cement-polymer mixture penetrating - one of the most modern and effective methods of waterproofing devices. The best proved mixture from the Greek company ISOMAT. They are environmentally safe and durable.
Since environmental cleanliness in a septic tank is not as important as in a well, the internal waterproofing can also be carried out using cheaper penetrations of Penetron Admix or Penekrit penetrating action. The mixture must be applied in 3 layers with a spatula. Cement-polymer waterproofing will last at least 40 years.
If a two-component mixture of CeresitCR 166 is used as insulation, then the service life of the waterproofing layer can be extended to 60 years. The prepared mixture should be applied to a wetted concrete surface without efflorescence using a brush.
On the first, not yet frozen layer, it is necessary to lay a reinforcing mesh and apply a second layer of the mixture. The two-component composition of CeresitCR 166 is characterized by high elasticity,which reduces the risk of destruction of waterproofing as a result of small displacement of the rings or their deformation.
Polymer blends for waterproofing
This material is the most expensive, but at the same time the most effective. The use of polymer blends will be justified when unstable septic tanks, in which there is a deformation of the rings. Maximum efficiency is ensured by high elasticity, achieved by installing the membrane on special mastics.
Best of all proved film polymer membrane. First, concrete rings must be treated with special mastic and left for 24 hours. The film has a glue base, it is enough to unfold the roll, press the film to the surface and smooth it to remove air bubbles. The service life of the insulation of the polymer membrane reaches 50 years.
The use of plastic inserts
One of the most reliable and simple ways to waterproof a sewer well is to use a multi-layer polymer or plastic insert. It has the shape of a cylinder, is equipped with a bottom, a lid and a neck. The height of the insert reaches 4.5 m, and the diameter can be 90 cm, 140 cm, 190 cm.
The wall thickness of the insert varies between 8-25 mm depending on the manufacturer.To prevent deformation of the insert reinforced ribs. Installation is very simple, just lower the insert in the well and fill the space between the walls of the insert and the concrete ring with a dry cement-sand mixture.
Sealing joints between concrete rings
Whatever method was used to waterproof the septic tank from concrete rings, it will not be able to ensure complete tightness without the mandatory processing of joints between the rings. Even at the stage of installation work between the rings should be laid waterproofing and shock-absorbing gasket.
It is best to use a rubber concrete pad. Granules of concrete clay, present in its composition, upon contact with water, can increase its volume by 3-4 times. Such a clay reaction makes it possible to fill cracks and voids present between the concrete rings of the sewer well.
The rubber-rubber liner has a high level of plasticity. This quality allows you to maintain the integrity of the septic tank, even in the case of a small displacement of concrete rings. Laying the gasket should not only be between the rings, but also when mounting the first ring on a concrete base.
You can do it easier and instead of an expensive rubber concrete pad put ordinary hemp, jute or flax rope. By themselves, the ropes will not ensure the tightness of the seam, so they must be impregnated with fibrous rubber. Laying the rope should be on the polymer-cement mixture, which can be replaced with a mixture of cement with white glue.
Conclusions and useful video on the topic
Installation of the lower ring on the slab, treated with a single component composition RABERIT:
The device of the clay castle around the concrete shaft:
Installation of a plastic insert in the sewer well shaft:
Whichever method is chosen for waterproofing a sewer well, all work must be carried out with the highest quality.The smallest defect can cause the destruction of the insulating layer and will inevitably lead to the need for re-waterproofing.