Polyurea: a revolution in waterproofing or just another myth

Recommendation points

• Characteristics of polyurea coatings
• Scope of Polyurea
• Benefits of Polyurea Compared to Traditional Insulation
• Disadvantages of polyurea and restrictions on use
• Insufficient resistance to UV radiation
• Moderate chemical resistance
• High cost of raw materials
• Expensive spraying equipment
• Pure polyurea or hybrid
• Features of applying a polyurea coating
• How much does polyurea coating cost

In this article, you will learn about a modern waterproofing material – polyurea. The main characteristics of polyurea coatings, the area of ​​application, as well as the advantages and disadvantages of this material in comparison with traditional waterproofing will be considered..

Polyurea (polyuria, polyurea) is a thick, highly elastic monolithic coating that is a film. It is formed by spraying a highly reactive two-component system onto the surface. At first glance, it may well seem that the product is not much different from polyurethane. Indeed, there is some similarity in their structure, but polyurea is a completely different coating with unique performance properties. It contains two components: isocyanate and resin.

As the second, polyether amines are used, at the ends of which there are very active amino groups. Their reaction rate with isocyanates is very high, even on very cold surfaces, and no catalyst is required. In comparison, polyurethanes have the same two-component composition. But instead of polyether amines, polyesters are used. It takes time and a catalyst to speed up the process for them to react with isocyanates. That is why the polyurethane film manages to get defects during the formation process, which seriously affect its subsequent operation. The polyurea system is completely devoid of this disadvantage..

Characteristics of polyurea coatings

The composition of polyurea determines its characteristics:

1. High strength and elasticity. The tensile strength of the material is about 38.5 MPa. At the same time, the polymer is characterized by the highest wear resistance, far exceeding even the standards for floor ceramic tiles..
2. The material does not contain solvents. It is completely solid with 100% solids content. Which makes it possible for polyurea to meet the most stringent safety and environmental requirements.
3. The highest curing speed of about 10–20 seconds and the good reactivity of the substance allows the coating to be sprayed under various conditions. At the same time, the air humidity does not matter, and the temperature should be above -28 ° C. The moisture content of the substrate can only affect the adhesion of the film, but not its quality. You can start operation in an hour.
4. Polyurea forms a monolithic seamless fabric of a given thickness, on average from 0.4 mm per pass. A drip-free coating fits on horizontal and vertical planes of any configuration.
5. Spray film solves problems related to moisture, wear and corrosion protection.
6. Excellent adhesion to almost all materials used in construction. Exceptions – PTFE and Teflon.
7. Good resistance to various chemicals. Aliphatic polyurea can resist the damaging effects of UV radiation.
8. High fire safety: the material practically does not burn and is characterized by the ability to self-extinguish.
9. A wide range of coating colors, allowing you to use it as a decor.
10. Durability and good maintainability of the polymer film.

Scope of Polyurea

Polyurea has a wide range of applications. Very good waterproofing properties of the polymer are used in the construction of various structures for moisture isolation of various types of roofs, foundations, basements, cellars, basements, bunkers, etc. As a waterproofing coating can be applied to any tanks and containers: collectors, pools, aquarium ponds.

As a corrosion-resistant and at the same time moisture-insulating coating, polyurea is used in the construction of piers, overpasses, pipelines, tunnels, river and sea vessels, piers, quays and bridges. For the same purposes, it is sprayed onto the inner walls of gas and oil tanks..

The polymer laid on the geotextile is used as a seamless membrane covering for earthen sedimentation tanks and pits. The material is also used in the construction of sewage treatment and sewage facilities..

For waterproofing works, the polymer is used in road construction.

As a corrosion and abrasion resistant material, polyurea is used in the arrangement of parking areas, protective coatings for cars, truck bodies, crushing and mining equipment, floor coverings.

As a decor and a protective layer for structures made of porous compounds, polyurea is used to create objects for entertainment and recreation, sculptures and art objects..

The listed options are a small part of the wide range of possible uses of a unique coating.

Benefits of Polyurea Compared to Traditional Insulation

The advantages of the new material are most clearly visible at the installation stage. Most of the usual polymer coatings, rubber, polyester, epoxy, etc., are stacked in several layers, which requires a long intermediate drying. Depending on the ambient temperature, which should only be positive, it takes several hours or even days for the material to completely harden..

Polyurea allows you to apply the desired film width in one pass. The coating can be used a maximum of one hour after installation. The negative influence of the seasonal factor during construction work is minimized due to the low sensitivity of the polymer to the temperature of the base and the environment. There is experience of successful coating on cold substrates with high heat absorption, such as steel at -20 ° C.

Conventional polyurethane spraying is extremely sensitive to moisture and requires many installation restrictions. It can only be applied to a well-dried substrate that is at least 3 ° C above the dew point. In this case, the relative humidity should be no higher than 80%. During installation work, the components of the working mixture should be reliably protected from contact with moisture contained in the atmosphere. Failure to meet all these conditions leads to deterioration of the coating, manifested in the form of micropores, foaming, craters, bubbles and small holes..

If we consider the speed of the curing reaction of polyurea, then it is very high. Under such conditions, the side reaction of the isocyant, one of the components of the coating, with water simply does not have time to pass. Thus, it is possible to prevent the appearance of carbon dioxide and, accordingly, damage to the coating. Such a low sensitivity of polyurea to moisture allows it to be laid with high quality in such conditions when other materials are simply inoperative..

Let us compare the traditional bikrost clad roof and the polyurea elastomeric coating. Bikrost is a material that is a durable panel on which a mixture of a binder based on bitumen and various fillers is applied. Its service life is no more than ten years. Whereas polyurea can be used for more than 50 years. When installing bikrost, the use of open fire is required. On average, a maximum of 300 square meters can be laid per day. m of the deposited material. No open fire is required when laying polyurea, but special equipment is used. Up to 1000 square meters can be covered per day. m.

Bikrost is more fire hazardous, its operating temperature, without compromising properties, varies from -30 ° C to +40 ° C. Whereas for polyurea, these values ​​range from -60 ° C to +150 ° C. Chemicals such as gasoline, acetone, hydraulic oil, hexane, etc. are hazardous to conventional material. Bikrost has poor resistance to them; they are safe for polyurea complexes. Traditional coating can be installed only with the presence of seams, sprayed on makes it possible to obtain a monolithic surface. A roof covered with bikrost cannot be used as an exploited one. Polyurea spraying allows you to transfer the roof to the category of exploited.

Disadvantages of polyurea and restrictions on use

Perfect coatings are unknown to builders, and polyurea is no exception. There are certain disadvantages that limit its use..

Insufficient resistance to UV radiation

This quality is not characteristic of all materials. Polyurea is divided into two groups. The higher cost aliphatic is less susceptible to UV rays. Materials created on its basis practically do not lose color. In cases where the appearance of the object is important, this type of coating is used. Aromatic polyurea differs in a more democratic cost, however, it changes color during operation. This is a purely cosmetic issue and does not affect its performance. To reduce the negative effect when using aromatic material, try to choose darker colors as a decorative coating – gray, brown, black, etc..

Moderate chemical resistance

Concentrated mineral acids, as well as some solvents such as benzene, acetone, toluene, antifreeze, xylene, brake fluid destroy the polyurea film. Highly corrosive chemicals also degrade the material. At the same time, the polymer is highly resistant to salt solutions, dilute acid and alkali, oil products and wastewater, which determines the possibilities of its use..

High cost of raw materials

The components for the production of polyurea films are the so-called “liquids A and B”, which are supplied in separate packaging. For the manufacture of each of the components, which occurs only in specialized enterprises, depending on its recipe, from 10 to 20 ingredients are used. All of them, as a rule, are expensive and, more often than not, are not produced in Russia. Accordingly, the cost of the final product will be high.

Expensive spraying equipment

Polyurea can only be applied to the substrate using special equipment. Its performance, pressure and heater power directly depend on the model of a two-component dispenser. The equipment of the device is also important: the presence of heated hoses, a recirculation unit and barrel pumps, the performance of the compressor, the brand of the spray gun. The total cost of the kit with the necessary spare parts varies from 27 to 40 thousand dollars. Only highly trained personnel can operate such equipment. His duties include not only applying a layer of film of a given width to the base of any configuration, but also maintaining complex equipment in working order.

Polyurea should not be overestimated. It really has unique properties, but only if the technology of its application is strictly observed. Spectacular commercials, in which the material was sprayed on an unprepared substrate or even water and ice, created the image of polyurea as a “problem-free” coating. This is not entirely true. The material requires careful preparation of the base for spraying, otherwise disappointment and serious material losses cannot be avoided.

First of all, you need to understand that, like any sprayed coating, polyurea is not able to hide the defects of the base. It will only emphasize all the differences and irregularities of the insulated plane. If a flat surface is required, it must be prepared in advance. Unpleasant surprises will await those who try to apply the polyurea film directly to the porous substrate. For example, cement-sand screed, concrete or plywood.

Lack of preliminary priming will lead to uneven adhesion and, as a result, the appearance of many defects in the form of craters. It is not possible to “cover” them even in several subsequent passes. Another myth is the possibility of applying a polyurea film to wet, unprimed steel. In general, polyurea can “forgive” minor imperfections on the substrate, but requires high-quality surface preparation. Otherwise, polymer adhesion is significantly reduced, and coating defects may appear..

Pure polyurea or hybrid

Polyurea systems are divided into two types: pure and hybrid. Polymers belonging to the first group are fully inherent in all the unique characteristics of polyurea. However, their cost is high. Hybrid polyureas are significantly cheaper, which makes them more affordable for the consumer. Partial losses of some performance, resulting from small changes in the composition of the material, are often not fundamental and do not interfere with the use of an insulating coating.

Today, the most in demand are polyurea and polyurethane hybrids. They are used as insulation where less stringent protective layer requirements may be imposed. Such mixtures differ in one significant drawback: the polyurethanes that make up their composition are much more active than pure polyurea, interact with moisture. Thus, the performance of the coating deteriorates somewhat, which imposes certain restrictions on its use..

However, “mixed” polymers also have an undeniable advantage: the composition of the mixture can be varied, creating a material with the specified specific properties. To obtain the desired characteristics, minimal changes in the formula will be sufficient. The result is a composition created to solve specific problems, which is very important for the harsh climatic conditions characteristic of our country. Depending on the additives used in the production of polyurea complexes, the finished material can be purchased:

• decrease in water absorption due to the addition of water repellents;
• additional resistance to fire when introducing fire retardants;
• elasticity with the addition of plasticizers;
• increase in wear resistance and hardness due to the use of hardeners;
• increased adhesion and elasticity in the case of adding silicone;
• additional resistance to aggressive chemical media.

The high cost of pure polyurea and its exceptional properties require the polymer to be used in harsh and extreme environments with high humidity or low temperatures. Whereas more economical hybrid materials are used more widely. A variety of variations of such systems allows you to choose the best option for any operating conditions.

The choice of polymer is determined not only by the functions to be performed. The properties of a hybrid coating, determined by its composition, affect the nuances of the application technology. For example, if the material contains plasticizing additives or surfactants, the intercoat adhesion will be very poor. Therefore, the film must either be applied in one layer or with a very short interval between spraying layers. These factors must be taken into account when choosing a polymer..

Features of applying a polyurea coating

The quality of the finished protective surface directly depends on the preparation of the base, which must be carried out very carefully. If necessary, the surface is leveled or large defects removed. Cleans from debris, dust or other contaminants. A possible loose layer and a substance called concrete milk are removed from the concrete. The brick is plastered with a sand-cement mixture, while a reinforcing mesh can be installed. It is imperative to use a primer that is suitable in composition, otherwise there is a high likelihood of defects on the laid coating.

Then you can start spraying the material. The most commonly used method of polymer deposition, which is used in 95% of cases, is spraying using special equipment. The operation is carried out in several stages:

• heating components
• supply of components to the mixing chamber
• mixture preparation
• spraying material on the base

The components must be heated separately. The procedure allows you to reduce the viscosity of each of the constituents of the polymer, which makes it possible to mix as efficiently as possible. The process is carried out in a special mixing chamber. Special conditions are created here. The pressure and temperature both inside the tank and the supplied mixtures must be high, this ensures a good quality result. In addition, given the high reaction rate of the polymer constituents, the procedure should be carried out as quickly as possible..

To ensure all these conditions, special two-component spray systems are used. The device performs precise dosage of components, mixing and fine spraying of the finished mixture using a self-cleaning gun equipped with a mixing chamber operating under high pressure. The system must be equipped with long heated hoses, up to 90 m, this allows you to quickly deploy the complex and lay the film over a large area without moving the installation.

It is important to choose the right equipment. The device must fully correspond to the specific polymer, since each requires a specific type of gun, size of the mixing chamber, operating parameters of pressure, temperature, etc. It should be borne in mind that two-component medium and low pressure pipettes equipped with mechanical or static mixers, which traditionally used for spraying less active systems, not suitable for spraying polyurea complexes.

Another way of using the polymer is by hand. This option is not very common and is used only when spraying is impossible for some reason. For manual styling, use a brush or roller and special polyaspartic polyureas. They contain esters that somewhat slow down the hardening reaction of the coating, which allows you to distribute the composition with a brush. In addition, they also allow you to extend the life of the protective film..

How much does polyurea coating cost

The cost of polyurea is quite high. It depends on a large number of factors and, first of all, on the composition of the polymer, which can be both “pure” and hybrid. In addition, the cost usually includes polymer spraying work. Their price also varies depending on the degree of complexity of the base configuration, material absorbency, surface temperature and many other factors. Thus, the average cost per square meter of polyurea film starts from 1,500 rubles.

If we compare this figure with the price of traditional materials, then for arranging the roof using the same bikrost, excluding the cost of thermal insulation, on average, it will take from 1000 rubles. per sq. m. For polyurea film will have to pay from 1500 rubles. per square. However, after five years of operation, taking into account the necessary current repairs, their cost becomes about 1,500 rubles. per sq. m. According to experts, the total cost of a polyurea coating can be considered 20% lower, which is facilitated by a long service life and high performance properties of the material.

Polyurea is a unique insulating coating. The high reaction rate of its constituents makes it possible to obtain a protective film with excellent performance, regardless of environmental conditions. At the same time, one should not forget about the competent preparation of the base, otherwise unwanted coating defects may appear. The limiting factor in the use of the polymer can be considered its rather high cost..

If you wish, you can somewhat mitigate this disadvantage by choosing a hybrid composition with a more affordable price. Prudence should be exercised, however, as the cost of the polyurea application is also quite high. You need to understand that expensive special equipment requires investment, as well as the payment of highly qualified personnel serving it. In general, serious financial investments in the arrangement of polyurea insulation over time will necessarily pay off with its long service life, as well as unique performance characteristics..