What are the additives to concrete for strength? Types and characteristics of materials. The best cement additives to increase the strength of concrete Additives to strengthen concrete

Because this thing is not quite ordinary. If you don’t know how to calm your rowdy neighbors, and good manners do not allow you to cause a scandal, then you need to act quietly but confidently. When requests to turn down the music and calm conversations do not work on them, you should move on to the heavy artillery.

Try to let them know how you feel about extraneous noise at late hours. Buy a vibration speaker, and it won’t take you much time to re-educate your neighbors. In addition, you will not hear the vibration and sound that they will hear.

Vibrodynamics. What is this?

The vibration speaker looks like a small steel washer with a diameter of 5 centimeters, located on a flat round leg. The leg unscrews and there is a membrane underneath it.

At the top there are two wires that have negative and positive poles. The vibration speaker stand is used to create vibration. As soon as you lean this device against any surface, all the sound and vibration will move to it. The device is made of high quality steel. Excellent tightness. The vibrating column can operate even in conditions of high humidity. By purchasing a vibration speaker, you will give a “great” gift to your neighbors and restore peace of mind to yourself.

How to connect a 25W vibration speaker? Take a regular column. Connect the speaker and speaker wires, matching the poles. Don't forget to extend the wire if you plan to move the speaker from one place to another. Now turn on the speaker, turn on the music and lean the speaker against the wall or any other surface.

You don't have to turn up the volume at full volume; a speaker for your neighbors will transmit sound and vibration to the surface 1000 times stronger than what you hear. For clear and powerful sound, it is recommended to remove all small parts from the surface. If you place the speaker on a table, make sure there are no handles or other small items. Vibration will be transmitted to objects, which will significantly degrade the sound quality.

If you connect the device to a home theater, the effect will be even stronger. If your cinema has output power less than 30 W, then you can safely connect a vibration speaker to your music center. But many people buy an “anti-neighbor” vibration speaker to combat noisy neighbors. This is especially true for houses with concrete floors. You simply lean this device against the ceiling, floor or wall, depending on which neighbors you want to “please” and turn on music or a movie.

Wireless Bluetooth Vibrating Speaker Adin - “Neighbor Killer”

If you are inconvenient to pull wires and you don’t want unnecessary red tape with cables, then there is a solution for you - a Bluetooth vibration speaker. The speaker can be connected via Bluetooth to any of your devices, be it a phone, tablet, computer, laptop or player. The power of this speaker is noticeably higher (26 watts) and the neighbors will definitely hear you.

Buy a vibrating speaker and organize an educational week for your neighbors. Night revelers are unlikely to be surprised by music at night. Record the sounds of a hammer drill or electric drill on a flash drive and turn on the “neighbor killer” vibration speaker at 7 am when leaving for work. After all, if you can listen to music at night, then why can’t you do repairs in the morning?

With a show like this every morning, your neighbors will quickly guess what they are hinting at. In addition, when approaching your door, the neighbors will not hear any noise from your apartment. They will have nothing to say against you.

Everyone will find their own application for a vibrating speaker. One of the most popular, judging by the reviews, is the fight against ill-mannered neighbors. Press the speaker to the ceiling and turn on the music. Believe me, your upstairs neighbors will feel like you’re visiting a nightclub, and barely audible music will be playing in your apartment.

To enhance the effect of the vibration speaker for neighbors above, you need to secure it to the ceiling with something, for example, with tape, placing a tennis ball on top. will press the speaker tightly to the ceiling, and the tape will help fix it. Anyone who is tired of staying up until the morning from their neighbors' night discos is worth buying a vibration speaker. The price of a vibrating speaker is acceptable, and really the question should concern the price if your nerves and healthy sleep are at stake.

Vibration speaker for neighbors (anti-neighbor)

Buying a vibrating speaker and using it to enhance the resonance of sound will be good decision. If you place the device on a table with the membrane facing up, this will greatly enhance the sound and bass power. A great excuse to take your party to a higher level. But remember that noisy discos should be held only during the daytime and not disturb the people living in your neighborhood.

If you come to work without sleep because the loud music behind the wall did not allow you to sleep a wink. If you can’t put your children to bed for a long time because of the constant screams of your neighbors upstairs, buy a vibration speaker and repay your neighbors in the same coin.

By purchasing a vibration speaker for your neighbors, you will let them know what discomfort they are causing with their lifestyle. Many people still don’t know what a vibration speaker is and what it is needed for. It may not be a multifunctional device, but, as they say, all means are good in war. Especially if this is a war between neighbors.

Characteristics (wired vibration column)

• Case material: metal;
• Resistance: 4 ohms;
• Power: 25 W;
• Size: 5 x 3 cm;
• Weight: 270g.

Equipment

• 1 x Vibration speaker.

Characteristics (wireless Bluetooth vibration speaker)

• Power: 26 Watt.
• Line-in: 3.5mm jack.
• Line Out: 3.5mm Jack.
• Connection: 3.5 mm audio cable, bluetooth 4.0, NFC support.
• Material: Aluminum alloy, acrylic (top cover).
• Battery: Li-ion, 3.7 V, 1400 mAh.
• Charging time: 2-3 hours.
• Working time: 6-7 hours.
• Bluetooth operating distance: up to 10 m.
• Frequency: 30 Hz - 18 kHz.
• Volume: from 65 dB. (depending on surface type).
• Dimensions: 85 x 90 mm.
• Weight: 500 grams.

Equipment

• Vibro bluetooth speaker Adin S8BT - 1 pc.
• USB charging cable - 1 pc.
• Audio cable 3.5 mm - 1 pc.
• Instructions - 1 pc.
• Box - 1 pc.

Instructions

You can increase the strength indicator in several ways. The first and most often used is to increase the amount of cement in the composition. The higher the cement content in the composition, the more effectively the finished composition resists various external loads. But an important factor that should not be forgotten is that strength increases only up to a certain point. Once past this point, adding cement to the cementitious material will have the opposite effect. Excessive amounts of cement will greatly reduce reliability, and therefore it is not advisable to completely ignore special tables to achieve even greater strength.

The main safety margin of concrete is provided by coarse aggregate. The size of the components and their quantity also play a role. For example, adding crushed stone or granite to it will give much more strength to the finished mixture than limestone and gravel. Therefore, in high grades of concrete that will subsequently be used in structures with significant loads, their use is recommended. Reinforcement is used everywhere in concrete structures, but practice shows that the presence of a frame very slightly increases the strength of concrete by . The main increase in strength is due to resistance to lateral loads and tensile effects. In the construction industry, this is an important factor allowing the use various options use of structures.

Caring for the concrete mixture after it is laid and various impacts also affect subsequent strength. This factor mainly includes various operations related to compaction concrete mixture. If you vibrate after pouring, the strength of the concrete increases. This procedure eliminates small air bubbles that cannot rise on their own and helps achieve a monolithic mass. Vibration should not be carried out for too long, as separation of the mixture will inevitably occur.

It takes time for concrete to acquire the necessary strength. This allows the components to set and form strong bonds between the components. Strengthening by concrete is precisely the process of setting the components together. If there are ideal conditions of temperature and humidity, the maturation period of concrete is 28 days, and after that the strength reaches 100%. At the same time, the process of gaining strength does not end there, but continues, increasing for a fairly long period of time, which guarantees some reserve.

The construction of a new type of buildings and structures dictates new requirements and standards that are close to European ones or which are such.

Thus, new building materials have appeared, among which there are modern types of concrete that have new, specific properties.

Let's take a closer look at the varieties of this material, their advantages and disadvantages, as well as the scope of application of one or another variety. The article is very long, so let’s make a plan of what will be discussed. The list under the topics is:

1. Types of binders for concrete solutions (cement, lime, gypsum, liquid glass, bitumen, polymer resins).
2. Types of aggregates for concrete solutions (sand, crushed stone, slag, expanded clay).
3. Types of modifying additives for concrete solutions (regulators of setting, frost resistance; plasticizing, reinforcing, porous additives, strength enhancers, corrosion inhibitors).

So, modern concretes are mortars consisting of binder, filler, water and sometimes special modifying admixtures. Each of the components can be of artificial or natural origin and have certain properties that will affect the scope of application. Let's consider the components of concrete and their origin and properties.

Types of binders for concrete solutions

The main component that ensures the strength of the concrete mixture after it hardens is the binder. Exist different types binders that provide strong binding, a kind of “gluing” various components into a solid (monolithic), stone-hard material. Let's consider the varieties of this component that are available in types of modern concrete, their list looks like this:

• cement;
• lime;
• gypsum;
• liquid glass;
• bitumen;
• polymer resins.

Modern binders for concrete mixtures sometimes undergo additional processing, as a result of which their properties change (in better side), and can also be supplied to the market in various forms (packaged, not packaged; stone, powder). Below we will talk and consider in detail them and their properties.

Cement binders. The most common binders used to produce concrete mixtures for industrial and civil construction.

Cement comes in different grades, which determine its consumption to obtain a concrete mixture of a certain grade. For example, in order to obtain concrete grade M100, you can take cement grade M400 in a ratio of 1:4 to aggregate (one part cement to four parts binder).

In addition, it is worth informing that there are varieties of cement, there are quite a few of them: Portland cement, white cement, hydrophobic cement, fast-hardening cement, waterproof expanding cement, tensile cement, alumina cement, magnesia cement, carbonate cement, oil well cement, sandy cement, expanding cement , plasticized cement, sulfate-resistant cement, pozzolanic cement, slag cement.

In addition, there is a special alkali cement, which is diluted with an alkali solution with the addition of other ingredients for preparing concrete and special slag, resulting in a slag-alkaline concrete mixture, a concrete composition that is acid-resistant.

Lime binders. They are quite popular in construction and have several features over other binders, namely: lime has bactericidal properties, that is, it prevents the development of fungus and mold; lime-based solutions do not produce efflorescence after setting and for the entire period of operation; products made from lime mortars get stronger over the years, unlike cement mortars, which gain strength within a month.

Concrete mixtures based on lime binder are called silicate concrete mixtures and can be heavy (filled with crushed stone) or light (filled with sand). IN modern construction Heavy concretes with lime binder are not used, since they are much less wear-resistant than cement ones, but plaster mortars with sand filler are widely used in plastering work.

This material of natural origin, like the previous one, and has quite a few weaknesses as: low strength, fear of water and moisture, high deformation rate. However, gypsum-based concrete (gypsum concrete) is used in construction.

Due to the fact that it sets very quickly and is a lightweight material, it is used in the production of artificial decorative products (stucco molding, bas-reliefs and sculptures, imitation of crushed stone, etc.), as well as blocks for constructing partitions.

Of course, there are special additives and a solution of urea acid that can minimize the disadvantages of gypsum concrete, but still, it is not used in the construction of load-bearing and critical elements of buildings.

This binder is used to obtain special purpose concrete, which is particularly resistant to water. Thus, these mixtures are widely used in hydraulic engineering construction. In addition, liquid glass often acts as an additive to cement mortars to improve their water-repellent properties.

However, in Lately Many more effective modifiers have appeared that are easier to use and can enhance the water resistance of concrete to a greater extent than liquid glass. However, they do not have the properties of a binder, so this list contains liquid glass, and not thousands of branded modifiers that the concrete composition can contain.

Resins of natural or synthetic origin, which are used as binders in concrete mortars used in road construction (asphalts).

Probably everyone knows the features of such concrete (asphalt), they are not water-based compositions, unlike the others, and they are also prepared at high temperatures and set as they cool.

Such concrete mixtures are carcinogenic and cannot be used in construction inside residential buildings. They carry out the production of roads and parking areas, airport runways.

Polymer binder. These components are synthetic binders, on the basis of which polymer concrete is produced, which is very cost-effective today in construction, especially in the production of self-leveling floors.

It is famous for its properties of being absolutely resistant to destruction by moisture, water, microorganisms, and also has excellent strength and deformation resistance.

There are quite a lot of these resins, the main ones are: furan, unsaturated polyester, urea, epoxy, coumaron-indene, thermoplastic. Like other concrete solutions, polymer concrete mixtures can be heavy, medium and light, which is determined by the type of filler. It is important to understand that a polymer concrete mixture is essentially a mixture of liquid plastic and filler, of which there are many varieties.

Depending on the proportion of binder to filler, the mixture acquires certain properties. That is, the more binder the concrete composition has, the more pronounced the properties of the plastic are, that is, bending strength, tensile strength, and impact strength. If the content of filler is highest, then such concrete exhibits the qualities of stone, that is, resistance to compression and a low coefficient of deformation.

Types of aggregates for concrete solutions

Aggregate in concrete mixtures is a component that determines the strength, density and weight of the finished concrete product. Modern aggregates for concrete vary in origin (artificial and natural), size and weight. Thus, today there is such a list of the main, most used types of aggregates in construction:

• sand;
• crushed stone;
• slag;
• expanded clay;

Fillers, as a rule, are high-quality materials and there are no defects as such. However, there are a couple of nuances that are vitally important, in the truest sense of the word. The first caveat is that if you purchase filler from a dubious supplier, then it is worth checking it with a Geiger counter for the presence of increased background radiation. The second is impurities, that is, for example, sand can contain so much clay that the solution comes out spoiled.

This component is a natural, fine-grained (up to 5 mm in size) fossil, which is mined in different ways. Thus, they distinguish between river and ravine sand, which have an origin according to their names.

Eat important nuance: gully sand has an admixture of clay and cannot be used in concrete solutions intended for the manufacture of reinforced concrete and other load-bearing (under tension) elements.

It is widely used in fine-grained mortars based on cement, lime and gypsum binders for use in plastering of premises and works on brickwork. Solutions based on sand aggregate are considered to be light.

Crushed stone filler. This is a natural stone material that has a fraction from 5 mm to 40 mm and it is believed that its high-density varieties are popular for heavy types of concrete solutions.

There are several varieties, heavy ones include: pumice, volcanic slag, volcanic tuff and tuff rows. The lungs consist of carbonate rocks(limestone, limestone) from siliceous rocks (opoka, tripoli, diatomite, spongolite).

When making the composition of concrete, it is necessary to understand that the shape of the crushed stone is important, on which the quality of the concrete depends. Best form It is considered round or square-like, as it fits best and forms an even distribution of aggregate in the binder.

In addition, there is also a filler fraction, which the smaller, the easier the mixture is considered to be laid. In addition, the smaller the crushed stone fraction, the less consumption fine aggregate into the mixture (crushed stone).

A varied filler, of which there are many varieties, they can be of artificial or natural origin.

Granulated slag is an artificial filler, as it is a waste product from blast furnaces (burnt) and can be different shapes and factions. There is also waste from fuel burnout, the so-called fly ash, the particle size of which does not exceed 0.14 mm and is used as an additive in concrete, classified as fine aggregates.

As for natural slag, these are fragments of volcanic glass rocks, provided in bulk form and in the form of fragments. Due to their porous air structure, they have low weight and density, hence their use in lightweight concrete compositions is justified.

Expanded clay filler. Perhaps the most popular filler among lightweight concrete with increased heat/sound insulation properties. It is obtained by firing special types of clay, which are prepared in advance in the form of granules. After firing, the clay swells and hardens, resulting in the formation of strong, porous granules with a fraction of 5 mm - 40 mm.

There is also expanded clay sand, which is granules with a fraction of up to 5 mm, respectively. Expanded clay is available in different brands, which determine its density.

A concrete composition with such a filler is called expanded clay concrete and is used for rough concrete floor screeds, blocks for partitions and other minor, non-critical work.

Types of modifying additives for concrete solutions

Modern building mixtures, including concrete mixtures, have a variety of modifying additives that impart new properties or enhance existing ones. This made it possible to expand the range of application of concrete solutions in certain climatic conditions.

They act in a mixture in different ways: some react with the binder, others act independently. In addition, they are aimed at improving various indicators; There are no universal additives, and therefore below we will consider their varieties and principles of action. The list is as follows:

• setting speed regulators;
• frost resistance regulators;
• plasticizing additives;
• reinforcing additives and strength enhancers;
• porous modifiers;
• inhibitors of corrosion processes;

Setting speed regulators. Such modern concrete additives are great for cases where it is necessary to speed up the process as much as possible. construction production. This is achieved by accelerating the setting time and, accordingly, reducing the time of technological pauses.

Additives work by reacting with the binder (cement) and accelerating the formation of a crystalline network. Consequently, within a day it is possible to achieve such strength of concrete that the formwork can be removed and further work can begin.

Frost resistance regulators. Very useful compounds when working in winter conditions. The predecessor of these regulators was ferric chloride, which was toxic and ineffective.

Modern additives for improving the frost resistance of solutions can make it possible to use the concrete composition even at temperatures down to -40 C. As a rule, these are salt additives that are dissolved in water, which is used to prepare concrete mixtures.

Plasticizing additives. These are special compounds that act in concrete in such a way that the solution contains more water. long time without delaminating, as this happens very quickly. This makes the installation process much easier.

The additive itself creates many small bubbles, which contain the components sand, binder and water. So if the solution separates over time, it is enough to shake it so that it comes back to for a long time gained plasticity.

Reinforcing additives and strength enhancers. As for purely reinforcing additives, these are mineral, organic compounds in the form of threads. This is usually fiber - basalt threads, which are added to the solution in a certain proportion.

In a mixture with binder and fine aggregate, as a result of mixing, a homogeneous mass woven into threads appears, which, as it hardens, demonstrates much better resistance to bending and tearing.

As for strength enhancers, this is chemical substances, which react with the binder, forming a more powerful crystalline network, resulting in an increase in the grade of concrete.

Porizing modifiers. A new type of construction additive that promotes the formation of air pores in the structure of concrete, making its density less. Thanks to them, the plasticity of the solution increases during operation, and in finished product increased heat/sound insulation properties are observed due to the formation of pores.

According to the principle of action, they are air-entraining (binding the solution with air, a volume of 6-12% of the volume of the solution), foaming (prepared in advance in the form of foam, added to the solution) and gas-forming (when added to the solution, they release gas).

Inhibitors of corrosion processes. Substances that prevent the development of corrosion processes, or, more simply, stop rust. It makes sense to use them in concrete compositions that are intended for the production reinforced concrete structures. Their essence is that, being inside the solution for a long time, the reinforcing metal carcass does not rust.

Thus, a rusty layer does not form, which reduces the adhesion of the solution to metal reinforcement products. In addition, if the concrete structure is not protected by waterproofing and is constantly exposed to moisture, and therefore gets wet to the reinforcement, the reinforcement is less likely to corrode.

) come down to the introduction of various additives into the concrete mixture, which have different effects.

Plasticizer

Plasticizer RS is an aqueous solution of a highly effective nonionic surfactant, which reduces water separation of mortars, increases workability and preserves the properties of mortar mixtures. The additive gives mortars high cohesion, both during transportation and on the construction site, stable air content throughout the entire period of use.

The additive is intended for the preparation of cement-based mortar mixtures, which are used for stone or brickwork, installation building structures during the construction of buildings and structures, for screeding and plastering various surfaces. The additive can be used for the production of lightweight mortars and concretes of varying densities. Does not contain chlorine compounds.

Superplasticizer

Superplasticizer S-3 used in concrete for:
giving concrete mixtures high mobility without reducing the strength characteristics of concrete (increasing mobility from the initial 2-4 cm to 18-22 cm);
improvements physical and mechanical properties concrete (strength by 125-140% of the original, frost resistance by 1-1.5 grades, water resistance by 3-4 grades)
reducing the time for heat and moisture treatment or the time for stripping concrete that hardens under natural conditions.
reducing cement consumption by 15-25%.
dosage 0.5-0.8% by weight of cement.

The plasticizer must first be diluted in warm water until completely dissolved, in liquid form the plasticizer immediately begins to work in concrete; if you add it in dry form, it will take additional time to dissolve it and mix the concrete. The plasticizer must be pre-diluted in water, preferably at a temperature of 25-30 degrees one hour before use. The calculated amount of superplasticizer is introduced into the concrete mixture with mixing water. To increase the technological effect (achieve greater mobility of the concrete mixture or increase its shelf life, with constant additive consumption), it is advisable to introduce C-3 with part of the mixing water 1-5 minutes after mixing the concrete mixture with the main volume of water.

Superplasticizer PK-1 is an aqueous solution based on esters of polycarboxylate compounds. It is a base product that does not contain lignosulfonate salts or naphthalene formaldehydes. Does not contain hardening retarders or accelerators and antifreeze modifiers.

The main purpose of the additive is to increase mobility from grade P1 to P5 or reduce water demand (up to 30%) of mortar and concrete mixtures. It is used for the production of various concrete and reinforced concrete products (including prestressed ones): panels, columns, paving slabs, piles, facade products, blocks, small-piece products, etc. The additive works effectively with various types cement binders. Does not cause water or solution separation. Increases the strength of concrete both at the early (1 day) and late (28 days) stages of hardening. Allows you to reduce the duration of vibration compaction. The additive is allowed to be used for concrete in contact with drinking water. Allows you to partially or completely eliminate heat and humidity treatment.

Superplasticizer PK-2 is an aqueous solution based on organic esters of polycarboxylate compounds. The additive is intended for the production of ready-mix concrete.

The main purpose of the additive is to increase the mobility of the concrete mixture from grade P1 to P5 and reduce its water demand (water-reducing effect up to 30%) while maintaining mobility over time (at least 2 hours). Provides high initial and final strength. Does not cause water or solution separation. Allows you to reduce the duration of vibration compaction. Does not contain chlorine compounds. The additive is allowed to be used for concrete in contact with drinking water.

Superplasticizer PKL-1 is an aqueous solution based on polycarboxylate compounds and lignosulfonate. Does not contain hardening retarders or accelerators and antifreeze modifiers.

The main purpose of the additive is to increase the mobility from grade P1 to P5 or reduce the water requirement (at least 25%) of concrete mixtures. It is used for the production of various concrete and reinforced concrete products (including prestressed ones): panels, columns, paving slabs, piles, facade products, blocks, small-piece products, etc. The additive works effectively with various types of cement binders. Does not cause water or solution separation. Increases the strength of concrete both at the early (1 day) and late (28 days) stages of hardening. Allows you to reduce the duration of vibration compaction. The additive is allowed to be used for concrete in contact with drinking water. Allows you to partially or completely eliminate heat and humidity treatment.

Superplasticizer PKL-2 is an aqueous solution based on a mixture of organic esters of polycarboxylate compounds and lignosulfonate.

The additive is intended for the production of concrete mixture. The main purpose of the additive is to increase the mobility of the concrete mixture from grade P1 to P5 or reduce its water demand (water-reducing effect up to 25%) while maintaining mobility over time (at least 2 hours). Provides increased initial and final strength. Does not cause water or solution separation. Allows you to reduce the duration of vibration compaction. Does not contain chlorine compounds. The additive is allowed to be used for concrete in contact with drinking water.

Plasticizers and superplasticizers marked "Winter" can be used at sub-zero temperatures environment up to -25°C.

Microsilica

Microsilica used to produce high-strength concrete, dosage 10% by weight of cement, in concrete it is used together with a superplasticizer.

The use of microsilica allows:

• obtain concrete of high strength and water resistance
• increase the resistance of concrete when exposed to acids and elevated temperatures
• replace part of the cement (up to 30-40%) while maintaining the strength of mortars and concrete.

Hardening accelerator (calcium chloride)

Calcium chloride additive used in the production of foam concrete, polystyrene concrete, concrete, wall stones, paving slabs and etc.

The “bottleneck” in the production of such concrete products as aerated concrete and foam concrete are the forms in which the cement mortar sets and hardens. The solution must be in the molds for a long time at a certain temperature and humidity to obtain sufficient (standard) strength. Difficulties increase with decreasing temperature, when the “downtime” of molds increases several times.

To reduce production costs, it is necessary to reduce cement consumption without loss of strength. In this regard, the use of a hardening accelerator is currently considered technologically and economically advantageous. The recommended dosage of the additive is 1-2% by weight of cement.

Hydrophobizing additive Hydromix Designed to increase the water resistance grade and reduce water absorption of structures made of concrete and reinforced concrete, cement-sand foundations experiencing pressure from groundwater, wastewater and rainwater.

The Hydromix additive is a dry powdery material containing active chemicals that compact the structure of concrete (mortar) and give it water-repellent properties. The additive does not affect the mobility of concrete or mortar mixtures, slightly reduces their delamination and water separation, and does not have a retarding or accelerating effect on the hardening of concrete. The additive is compatible with almost any plasticizing additives.

The additive increases the water resistance grade of concrete up to 3 levels (0.6 MPa) and reduces its water absorption by at least 30%. The additive helps to increase the frost resistance of concrete and protects it from various aggressive environments. It is used without restrictions for use in domestic and drinking water supply.

The introduction of the additive makes it possible to raise the waterproof grade of concrete from W8 to W14.

The additive is used in an amount of 2 kg. per 1 m3 of concrete or mortar mixture.

Water-repellent impregnation

The aggressive effect of water on structures made of brick and concrete is a long-established fact, because these materials have a fairly porous structure. Water enters the structure from below. This - groundwater, i.e. solutions of salts: chlorides, sulfates and bicarbonates, which then, after the water evaporates, “decorate” facades, destroy foundations, tear off plasters and cladding.

Water also threatens from above, and this impact is very ambiguous. Rainwater, penetrating into the pores of the material, increases in volume at subzero temperatures and can cause local destruction. In addition, strictly speaking, rainwater is also a solution. Rain streams are captured from the atmosphere a large number of gaseous industrial emissions such as oxides of carbon, sulfur, nitrogen and phosphorus, such as ammonia, chlorine and hydrogen chloride. These gases, partially dissolving in water, turn rain into an acidic solution that has a destructive effect on concrete, marble, sand-lime brick and other materials. At the same time, the number of pores, capillaries and microcracks, which are increasingly new foci of aggression, increases, and the degree of destruction of the material increases significantly. Even a very small content of acidic oxides of sulfur and nitrogen, as well as hydrogen chloride, in the air can cause a shift in such an environmental parameter of the atmosphere as carbon dioxide balance.

At the same time, the content of free carbon dioxide in the air, called “aggressive” in this case, increases significantly. Carbon dioxide is aggressive towards minerals building materials(lime, marble and concrete), converting insoluble calcite into water-soluble calcium bicarbonate. There is an elementary leaching of material from additional education cracks, pores, shells, etc. Concrete ages, plasters peel off, marble becomes dull, and characteristic “drips” appear on its surface.

The problem of protecting the material from moisture is solved by various methods of hydrophobization (water repellency). This is the use of all kinds of waterproofing methods, the use of liquid glass that closes pores, the production of high-density materials with a minimal porous structure, etc.

One of the promising areas of hydrophobization is the use of various organosilicon compounds that have the ability to hydrophobize. Organosilicon liquids, the basis of which is a silicon-oxygen chain (-O-Si-O-Si-O-Si-)n of adjustable length, contain hydrophobic hydrocarbon radicals of different sizes near the silicon atoms: C2H5, C3H7, C nH2n-1, which gives them depending on the purpose, both different degrees of water-repellent properties and different ability to penetrate into the material. Variations of these combinations make it possible to obtain water-repellent systems used for a wide variety of purposes related to the problem of hydrophobization. These are paints, coatings, impregnations, water-repellent additives for concrete and mortars, and a number of other areas.

An essential important circumstance in this case is the ability of organosilicon liquids not to close, but to line the pores, creating the thinnest waterproof film on their surface.

Polyurethane and acrylic protective coating

Polyurethane and acrylic coatings are a highly effective means of protecting surfaces, even with extremely small layer thicknesses at a consumption of 0.25 kg/m2. When processing stone or concrete, it emphasizes the surface structure and creates the effect of wet stone. The small working thickness of the layer makes the coating fireproof. When exposed to a flame source, the coating does not burn, but only decomposes under the influence of temperature, without creating a danger of fire spread.

These coatings have the highest adhesion to the treated surfaces, have a long service life (indoors up to 50 years, in an open atmosphere for at least 15 years), and do not harm human health even in direct constant contact with drinking water and food.

Polyurethane coatings provide hydrophobicity to building materials (concrete, mortar, brick, gypsum, cardboard, wood, etc.), and, accordingly, do not allow aqueous substances, salt solutions, oils, petroleum products, acids, alkalis and other materials to be absorbed into them which may affect the integrity and durability of these materials.

The protective coating is a two-component composition. Used as a transparent protective paint coating for surfaces made of concrete, metal, wood. A completely dried coating has high gloss, strength, elasticity, as well as resistance to abrasion and chemical attack and completely retains all decorative qualities.

Polypropylene fibers (fiber fiber)

1998 marks 15 years since polypropylene fibers (fiber fiber, PPV) for concrete began to be widely used throughout the world. Today in the US, 10% of all ready-mix concrete contains PPV, and millions of cubic meters of such concrete are poured in the UK. The fibers are currently used in structural concrete for marine fortifications, bridges and reservoirs, as well as in precast concrete and shotcrete. New developments include antibacterial concrete, thin concrete for asphalt roads, exposed aggregate concrete with a rustling surface, and concrete that is less susceptible to explosive spalling when exposed to fire.

Polypropylene fibers are olefin fibers made from polymers or copolymers of propylene. Molten polypropylene is stretch-stamped to form even sheets or fibers. Two types of PPV can then be obtained from it. The flat sheets are split into small fibrous elements that make up the main structure and cut into pieces of varying lengths. These fibrillated fibers have a cross-sectional shape close to rectangular. Fibers with a circular cross-section are also cut into different lengths to produce mono- and multifilament fibers. PPV is a clean, safe, easy-to-use, chemically neutral fiber that is compatible with all binders and additives.

The number, type and length of fibers used depend on the project requirements. The usual dosage is 0.1% by volume or 0.6 - 0.9 kg/m3 of concrete. For ease of use, PPV is supplied in soluble bags of 0.6 - 0.9 kg. For every cubic meter of concrete, one bag is added - either to the mixing plant at the concrete plant or directly to the concrete mixer. Just 5 minutes of mixing in a concrete mixer is enough to ensure even dispersion without the formation of lumps or accumulations. Higher dosages, especially of fibrillated fibers, are used in precast concrete, shotcrete and other types of concrete where strength and resistance to splintering is important.

At a dosage of 0.1-1%, PPV does not provide primary reinforcement. Theory shows that the amount of fiber that can withstand stress after cracking - the critical fiber volume - for PPV is approximately 2% by volume. This amount is difficult to incorporate into the concrete mixture and is not commercially acceptable. However, a dosage of 0.1-1% PPV by volume does provide certain benefits to concrete in both the plastic and hardened states. The fibers have an immediate effect by increasing the cohesion of the concrete mixture, preventing large, heavy particles from settling during compaction and making it easier to pump the concrete mixture. PPV increases the ability of concrete to deform without destruction during the critical period of setting, which prevents the formation of microcracks inside hardened concrete, and also inhibits the expansion of visible surface cracks that arise during plastic shrinkage. PPV prevents the movement and subsequent evaporation of water, increasing the hydration of cement at the surface, but does not replace proper concrete curing procedures. 16 years of independent testing worldwide, now backed by BBA certification, have shown that PPV at 0.1% by volume provides resistance to water bleed, slump, shrinkage cracking, abrasion, freeze/thaw cycles, impact resistance, and fire resistance, residual strength, antimicrobial protection and reduced permeability.

The advantages described above mean that PPV can be used in all areas of concrete application. The benefits of PPV are visible when analyzing the costs even for such structures as bridges, reservoirs and embankment walls. But the material has been used most successfully in concrete pavement slabs, especially where it has served as a replacement for recycled steel wire reinforcement. Calculations for concrete coating slabs with PPV are no different from the usual ones set out in technical report No. 34 of the Concrete Society. PPV does not increase permissible load concrete slab of given strength and thickness. Ease of use, the elimination of steel reinforcing wire mesh and unobstructed access for unloading concrete mix make laying concrete with PPV faster and more economical. Considering the surface advantages of such concrete already described, it is not difficult to understand why it is used with such success in covering slabs. The advantages of shotcrete with PPV are better adhesion of the concrete mixture, which reduces rebound and speeds up installation.

With a high dosage of longer fibrillated fibers, its strength can be compared to concrete containing 25-30 kg of steel reinforcement. The advantages of precast concrete with PPV include a reduced risk of accidental damage during stripping and subsequent transportation, reduced permeability and, therefore, less susceptibility to corrosion. The advantages of concrete with PPV when using sliding formwork are better adhesion of the concrete mixture, which helps to increase the pace of construction and reduce the volume of repair work.

High performance concrete, with a strength of 60-100 MPa or more, is becoming increasingly popular throughout Europe. However, as the Channel Tunnel fire showed, such concrete is susceptible to explosive spalling at temperatures above 200 degrees Celsius. PPV allows superheated steam to escape safely through capillaries to the surface when polypropylene melts at 160-170°C, and PPV is now being introduced into concrete specifications for tunnels and other applications where explosive spalling can be life threatening.

Magnetization of mixing water

It's impossible to start without water chemical reaction, transforming the disparate components of the concrete mixture into a single monolith. Its role in this process is difficult to overestimate. Therefore, the desire to modify many chemical processes occurring in the presence of water, including the formation of cement stone, is quite understandable, precisely by changing some of its properties.

In concrete science, the role of modified water is one of the most controversial and little-studied topics. Despite the fact that, with a periodicity of approximately 10 years, concrete scientists around the world return to this topic again and again, the factors influencing changes in the characteristics of concrete caused by the use of modified water remain largely unclear. All this led to the division of concrete scientists into two opposing camps. Some, foaming at the mouth, claim that shamanism over water is clean water quackery unworthy of serious researchers. Others, just as fiercely, argue the opposite. The truth, as always, is somewhere in the middle.

Talking about the role external factors external interference during the magnetization of water systems, the so-called seasonal dependence of the results cannot be ignored (although this issue is considered by geocentrist scientists invariably skeptically). For example, it has been repeatedly confirmed that the magnetization of water used for mixing cement mortars is least effective in May-July. Repeatedly conducted experiments convincingly and unambiguously indicate that under absolutely identical conditions, the increase in the strength of samples sealed with magnetized water was 50–60% in January, 2–5% in May, 20–25% in September, and 40% in October. The reasons for such seasonality have not been precisely established. One can only assume that the geomagnetic influence of the sun “interfered” with the experiment. In any case, they cannot be associated with the influx of melt water, since the experiments were carried out using double distillates.

In any case, even without knowing how “IT” works, humanity has long and very effectively learned to use the magnetic effect on substances, including water, for its own purposes.

In the USSR, the beginning of the use of magnetized water for mixing concrete dates back to 1962 (Neiman B.A. USSR Certificate No. 237664, dated 1962). Since then, significant research in this direction has been carried out and continues to this day. It is known that during the hardening of cement stone a number of complex processes simultaneously occur: dissolution and hydration of cement minerals with the formation of supersaturated solutions, spontaneous dispersion of these minerals into particles of colloidal sizes, the formation of thixotropic coagulation structures and, finally, the emergence, growth and strengthening of crystallization structures. And the magnetization of water affects all these processes. Consequently, the influence of magnetic treatment of water used for dissolution on the hardening and properties of cement stone is quite natural.

Experiments have established that mixing cement with magnetized water leads to a significant increase in the strength of the stone. Moreover, the dependence of strength on field strength is extreme.

All improvements in the strength characteristics of concrete are due to several factors that are influenced by the magnetization of water. The main ones are the accelerated increase in the plastic strength of cement stone, measured by the ultimate shear stress. When mixing with ordinary water, there is a significant induction period for cement crystallization. In the case of mixing with magnetized water, the plastic strength begins to actively increase almost immediately after mixing. At the same time, there is a faster dispersion of particles down to micron sizes.

Microscopic studies also showed an increase in the rate of hydration of cement in magnetized water. Moreover, the number of crystals of calcium sulfoaluminate and calcium hydroxide increases significantly, and their sizes decrease. Crystals are found not only on the surface of the grains of hydrating cement, as usual, but also throughout the entire mass. A study of three-day-old cement stone under an electron microscope showed that in magnetized water the structure of the stone is much more fine-grained. In addition, numerous experiments have shown that the effect of magnetic treatment of water largely depends on its chemical composition. Impurities of iron ions and chlorides most often have a positive effect. Some gases are residual chlorine, ammonia is negative. Hardness salts play a very important role, both by themselves and their mutual ratio. It has been reliably established that the best results are achieved with the following salt concentrations: magnesium sulfate – 1.2 g/l, calcium sulfate – 1.2 g/l, magnesium chloride – 2.8 g/l.

Numerous experiments assessing the influence of magnetized water on concrete clearly indicate that the effect of magnetic treatment is extreme. There is a certain optimum, both in terms of magnetic flux intensity and the speed of water flow, as well as its mineralogical composition. It is different for each industry that uses magnetized water. The practice of thoughtlessly using magnetizing devices designed to work in other technological chains should be considered deeply erroneous, vicious and even harmful.

The most interesting thing about the design of the magnetizing device is that it absolutely does not need any copy protection. You can cut the device, measure it, or at least taste it. Until you figure out the magnetic strength of the magnets used, all your attempts to make a similar device will be in vain - you simply will not get the desired effect.