Stress cement

Special qualities of the composition

A film is formed that is resistant to friction, scratching, and mechanical stress.

The answer to the question why the product remains in demand will be clear if the qualities of the NC-132 composition inherent in nitro enamel are considered:

High resistance on the film surface to water, household chemicals, frequent wet cleaning with detergents

The composition is used in rooms with high humidity.
An important advantage of the NTs-132 product is that the painted surface will not suffer from grinding and polishing. On the contrary, the decorative layer acquires an enhanced shine.
Enamel belongs to economical materials, consumption is low

It is easy to work with.
Protective and decorative coating with a long service life, with a high drying rate.
The coating has anti-corrosion properties.
For a long time, the brightness of the color of the enamel layer remains under the influence of direct sunlight.

Scope of application

The material can be used in a number of cases:

providing waterproofing of objects that are constantly exposed to moisture, including basements, basements, etc.;
protection of surfaces exposed to the simultaneous action of intense mechanical stress and water, for example, swimming pools;
construction of facilities subject to extreme pressure: runways, floors of industrial premises;
restoration of the properties of old structures, repair of seams and joints of concrete slabs;
construction of bridges;
roof installation when monolithic concrete elements are used.

Peculiarities

A distinctive feature of stress cement is the fact that it cannot be mixed with any other type of cement. Its astringent and expanding qualities "suffer" from this. Even if the funds are not enough, you cannot include other additives in it that should not be in the composition.

At the same time, the refractoriness of the material may also decrease, which is important in any construction

The use of stress cement allows the concrete to be given high technical properties. When solidified, the composition increases in volume. Expansion can be seen as early as 3 days after using the mixture. In this case, the concrete will harden faster than with traditional cement. At the same time, the speed of hardening will not have a negative effect on the quality of the coating. The strength of the composition will also be high within three days after its application.

The material is characterized by increased bending strength. If necessary, it can be laid on old concrete, while the adhesion level remains high. The composition is characterized by low gas permeability. In real construction conditions, it provides all those quality characteristics that are necessary for each specific case. Moreover, they will be higher than that of other formulations with modified additives.

With its many positive characteristics, stress cement has disadvantages as well. For example, despite its durability, such material is not cheap. For this reason, unscrupulous companies often counterfeit this type of cement. It can be difficult for an ordinary buyer to distinguish genuine material from counterfeit. However, the problem can be solved by requiring a quality certificate.

Another disadvantage is the fact that not every type of stress cement is resistant to low temperatures. Under the influence of cold, some types of material may lose some of their properties.

Application area

Stressing cement is used to make so-called self-stressed concrete, which is characterized by the absence of shrinkage during drying and operation.After pouring and hardening, it does not crack, therefore it is ideal for the manufacture of screeds, foundations. With the help of the material, you can repair or strengthen ready-made foundations and structures where there is a high level of groundwater.

Pouring self-stressed concrete screed

Concretes based on this material are waterproof, so they are suitable for the construction of sewers, drains, drains, collectors and swimming pools. On the basis of NTs cement, waterproofing building mixtures are made for the construction of treatment facilities or structures that are constantly exposed to water and aggressive substances.

Other areas of application of the material:

construction of pipelines, structures in areas with difficult terrain, in a harsh or changeable climate;
arrangement of structures experiencing high static and dynamic loads;
construction and strengthening of reservoirs for water, oil products, chemicals, toxic waste;
casting of vertical elements of structures, floor slabs, waterproofing barriers;
sealing cracks, chips, joints, seams and other defects on any planes;
creation of industrial facilities, runways, treadmills, highways, especially those subject to heavy loads;
construction of fireplaces, stoves, boiler rooms;
concreting of basements, basements, garages and other semi-underground and underground structures.

In addition, cement powder is introduced into the composition of various ready-made composite mixtures to enhance their strength and reduce the shrinkage rate. In general, the material is widely used in multi-storey monolithic construction, but it is no less popular in private buildings.

Changed transcript names

Today, manufacturers adhere to GOST 31108-2003 and produce:

CEM I 32.5B - Portland cement (hardens quickly, its strength is 32.5);
CEM II / V-Sh 22.5N - Portland cement with a slag capacity (fortress - 22.5);
CEM II / A-I 32.5N - the same brand, only with the capacity of the rock containing lime, the characteristics are the same;
CEM V / A-K (Sh-3-I) 32.5B - an astringent diluted with additional ingredients: granular ash, limestone. It differs in that it instantly grasps;
CEM III / A 32.5N - cement, which is characterized by a significant capacity of granular ash. The product hardens well;
CEM IV / A (P-Z-MK) 32.5N - mainly contains a dusty mixture of volcanic ash, pumice, tuff and others;
CEM V / A (SH-3) 32.5N - this name suggests that the composition of the mixture contains the capacity of ash residues in granules, which, when used correctly, sets perfectly.

According to GOST, cement is:

SSPTs 500-D20-PL is a hardening material resistant to sulfates, which is sold under the M500 brand. It also contains about 2% mineral additives, which makes it more plasticized;

SSPTs 500-D20-PL

SSSPTs 400 - slag cement is also resistant to sulfate minerals and salts, produced under the name M400;
PPTs 300 is a super strong cement capable of hardening both in liquid and in any humid environment;
NTs-20-M500 TU 46854090 - cement with excellent performance characteristics, has a huge self-tension in 28 days;
PCB 2-400-D20-PL GOST 965-89 - light beige free-flowing powder containing second-rate additives, marked on the bag with the number 400, has good plasticity, which makes it easy to stack;
GOST 10178-85 involves the production of two types of this binder building material:
PC 400-D20-B-PL is a cement made from clinker, gypsum and additives, together with calcium silicates, which prevail in it. By the way, it is the most widespread in the world and is used in all kinds of construction and finishing works, it is produced under the brand name 400, is easy to operate, quickly hardens;
ShPTs 400 is a slag binder with the same strength as M400.

A wide selection of this product is produced according to DSTU B V.2.7-46: 2010:

PC I-400R-N - concrete production cement M400 from clinker and uniformly containing composition;
PC II / A-Sh-400R-PL - slag cement with a ratio of 6% -20%;
PC II / A-K (Sh-V) -400 - the same material with the addition of limestone;
PC II / B-K (Sh-Z) -400 - Portland cement with granulated slag and ash;
SPTs III / A-400 - pure slag-binding binder powder;
PCC IV / B (P-Z) -400 - pozzolanic cement with ash admixture;
КЦ V / А (Ш-З) -400 - composite cement with slag and ash.

You can find out more about cement brands and decoding in the video:

Expanding and stressing concretes

Comparative characteristics of binders

Stressing concretes are mixtures based on stressing cements, capable of increasing in volume in the initial phase of hardening and stretching the reinforcement in direct contact, which, as a result of such processes, receives the effect of self-stress (compression).

Moreover, the reinforcing bars are stretched regardless of their direction and arrangement in the structure of the product, which contributes to obtaining biaxial volumetric self-stress of structures.
The mechanism of action of expanding materials is based on the creation of controlled directional crystal formation during the hardening of the cement stone, which contributes to the regulation of the process of volumetric deformations in the plastic structure of the product.
The use of expanding fast-hardening concretes, due to controlled linear expansion, can significantly compensate for the effects of shrinkage deformations, increase crack resistance and service life of buildings and structures.

Properties

Properties of structures with expansion additives

In practice, there are two main types of expandable materials:

with a standardized size of compression;
with compensated shrinkage, but with abnormal self-tension (compression).

Main characteristics of stress concretes (GOST 32803-2014):

For heavy, the following compression classes are provided: B20 — B90; tensile - B_t0.8-B_t4,0.
For light: for compression - B10 — B40; tensile - grades B_t0,8—3,2.
Taking into account the magnitude of the stress, concrete is classified according to the following grades: Sp0.6—4.0.

Frost resistance F200-F
Water resistance: heavy - W12 - W20, light - W8 - W
This material has high strength (40–70 MPa). Moreover, the growth of this value is observed especially intensively at an early age (28 days). After three months, the tensile-compressive strength increases by 30%, and upon reaching 6 months, by 40%.
There is no corrosion of the reinforcement.
High sulfate resistance.
Gas permeability is 40 times lower in comparison with heavy concrete based on Portland cement.

Application

Prestressed structures

The noted properties of this material allow its effective use both in monolithic and prefabricated reinforced concrete structures:

during the construction of load-bearing elements and the roadway of bridges, which made it possible to increase the bearing capacity by 12-16%;
for the construction of energy facilities for thermal power plants, hydroelectric power plants, nuclear power plants, etc.;
for prefabricated construction of subway tunnels;
when erecting tensioning structures for sports purposes (indoor sports arenas, etc.);
in the production of high-pressure reinforced concrete pipes;
for equipment of roof coverings and construction of durable industrial floors;
widespread use in the construction of reliable waterproofing coatings applied by shotcrete.

Materials (edit)

Expandable concrete is produced on the basis of tensile and non-shrinking cement using coarse and fine aggregates of natural origin.

The use of expanding concrete for structural repair is similar to the use of conventional concrete or cement mortar, with some peculiarities.

The surface to be repaired is thoroughly cleaned of amorphous mass and dirt.
Before applying the expanding mortar, the concrete base and reinforcement are thoroughly moistened.
To obtain a repair composition, expanding cement is mixed with clean sand in a ratio of 1: 2, mixed with clean water in an amount of 40-50% by weight of the cement and thoroughly mixed.
The solution is applied by pneumatic spray and injection with special syringes.
The surface of the structure is covered with plastic wrap and kept moist for 7 days.
Mixing of expanding cement with general construction materials is not allowed.

Starting putties for walls - types

In terms of composition and intended purpose, the starting putty is a transitional stage between plaster and finishing mixtures. It, like plaster, is used to treat rough surfaces. However, at the same time, the structure of the starting putty is not as coarse as that of plaster and allows the application of a finishing layer.

In particular, start putty is suitable for:

finishing around door and window frames;
filling strobes;
alignment of slopes.

Starting putties are divided into homemade and ready-made mixtures. They resort to self-preparation of the putty, if necessary, to save financial resources. In this case, all the constituent parts are mixed in the right proportions. It can be gypsum-chalk and oil mixtures.

However, in practice, this happens quite rarely. Basically, ready-made mixtures are used for repairs. In them, all the constituent parts are selected, and the only thing that needs to be added is the right amount of water. Ready mixes are of the following types:

cement;
gypsum;
polymer.

Here is a list of the most common companies that produce starter putties.

Volma. The company specializes in the production of ready-made putty mixtures and produces base and finishing putties. There are several starting mixtures:

Aquastandard is a cement putty used to level surfaces for decorative coatings - textured paint, plaster.
Volma-Standard base putty is a gypsum-based mixture used for the main leveling of walls, ceilings for painting, wallpapering, decorative plaster.
Base cement putty. Designed for basic finishing of walls and ceilings in dry and damp rooms. It is also used for facades.

Prospectors. Russian manufacturer of starting putty.

White cement-based mixture is used indoors and in facade finishing. Does not crack or shrink. When dry, the putty forms a waterproof layer, therefore it is widely used for repairs in bathrooms and toilets. Surfaces can be easily sanded both by hand and using special equipment.

Knauf. Ready mixes Knauf are deservedly considered one of the market leaders.

Combining the high quality of the constituent materials and ease of use, they are loved by many builders and repairmen.

Knauf putties are of 3 types:

starting;
finishing;
universal.

Knauf starting mixtures:

Start Rotband for indoor use - used for leveling brick, concrete, expanded polystyrene, gas-block bases, easily applied to walls and ceilings.
Knauf Goldband. Possessing the above properties, Goldband is used only for wall decoration. It contains no adhesive components. This mixture works well when processing concrete and brick walls with deep depressions. It is applied in a layer up to 5 cm.
Knauf Fugenfüller. Starter type gypsum putty for sealing drywall joints. It is characterized by special strength and crack resistance.

Vetonit. The Vetonit company is represented by a wide selection of starting and finishing putties.Vetonit TT Starter putty for dry and damp rooms. It is applied in a layer up to 6 mm., Does not crack, is not afraid of frost.

Acrylic fillers. The main substance that determines almost all the characteristics of such a mixture is synthetically made acrylic. It has a unique ability to change its properties depending on the conditions acting on it. The advantages of such a putty in:

high plasticity of the created surface;
creating a water-repellent layer;
fast drying;
easy application and sanding;
environmental friendliness;
fire safety;
no shrinkage;
long service life.

Acrylic starter fillers are designed to correct the most serious defects and surface imperfections. Acrylic putty mixture is produced ready-made - in plastic buckets. Among the firms producing acrylic putty, one can distinguish Ural quartz, Lacra, VGT, Parade.

Views

There is no official classification for cements. In the most general terms, several groups of compositions can be distinguished, the criteria of which are based on various parameters.

So, depending on the purpose of the composition, general construction and special compositions are distinguished. If the composition is taken as a basis, then you can designate options with min. additives and clean cement.

If you classify cement depending on the rate of hardening, then the following options are most common:

quick-setting mixtures - those whose setting speed is less than 45 minutes;
normally setting - harden within 45-120 minutes;
slowly hardening - harden for more than 2 hours.

Stressed, refractory, self-expanding cements and many others are also distinguished.

Let's dwell on the most popular types:

White cement is a material that is made from low-iron clinker, which is bleached. It is a material with unique properties, it can be used not only for bonding surfaces, but also for the manufacture of sculptural elements and columns, as well as for cladding the facade of a building. Due to its color, the use of white cement can improve the aesthetic component of the surface. By adding certain pigments, colored cement can be obtained.
Waterproof expandable cement is a substance with a high setting and hardening rate. It is produced in the process of simultaneous grinding of cement, gypsum and calcium hydroaluminate. Such cement begins to set after 4 minutes from the moment of mixing, and finally dries up after 10 minutes.

Waterproof non-shrinking cement - the main composition of the components of such cement is the same, however, the processing and production technology makes the hardening rate even greater - it takes no more than 5 minutes for the composition to dry completely. Such a composition is used to form a waterproofing shell of concrete goods.
Fast hardening Portland cement is a cement that is finely ground, making it more intense than standard Portland cement. The material gains special strength in the initial stage of hardening - after 1–3 days. Most often it is used when carrying out repair work.
Plasticized Portland cement is a composition, during the production of which 0.25% mash on a sulfite-alcohol basis is introduced into the grinding of clinker, due to which the frost resistance of the mixture and its plasticization significantly increase.

Hydrophobic cement - made by joint grinding of Portland cement clinker and gypsum, as well as by introducing axilol or another hydrophobizing additive into the composition. The water absorption of such cement is low, therefore it can be stored for a long time even in conditions of high humidity and this will not in any way worsen its physical and technical characteristics.Such a mixture does not form lumps, and concrete based on it does not crack over time and does not delaminate.
Alumina cement is a hydraulic binder made from raw materials rich in alumina, usually limestone or bauxite. The material hardens in low temperatures, therefore it is widely used for repair work in the winter season.
Magnesia cement - obtained from raw materials rich in magnesium oxide. It has found application in the arrangement of magnesia floors.

Portland cement - is obtained by grinding Portland cement clinker with gypsum and special additives, the firing technology is built in such a way that the resulting product retains a high content of calcium silicates.
Pozzolanic Portland cement - these building materials include components of volcanic origin in their structure. This composition quickly hardens both in the open air and in water, while mixtures based on such cement do not give any efflorescence and are highly hygroscopic. As a rule, such material is used in the equipment of swimming pools.
Acid-resistant cement uses quartz sand and sodium silicofluoride in the manufacture, such a composition is resistant to most mineral and organic acids, it does not change its characteristics in water. However, when it reacts with alkalis, it begins to break down.

Self-expanding cement types and properties

It is a product obtained by thoroughly mixing cement with certain mineral additives. When diluted, chemical reactions take place. The solution either crystallizes or many small bubbles form.

Due to this, during the hardening stage, the mixture increases in volume. There are brands of products with a record setting time - from eight minutes. Such characteristics of self-expanding cement make it an ideal material for rebuilding walls, working with reinforced concrete structures, building basements, shafts, etc. The convenience of this material is that the expansion of the mixture allows you to fill in the smallest cracks, irregularities, chips and similar defects.

Today, there are about five main types of these products. Each of them, depending on the composition, has its own properties and its own field of application:

Waterproof. What is the scope of self-expanding cement? It is most commonly used for waterproofing. Unlike other types, it has the smallest expandability, therefore such a composition is used as external and internal plaster. The peculiarities of the composition allow achieving a very high setting speed, and due to linear expansion, the dried surface will be ideally smooth. The final hardening of the mortar depends on the ambient temperature. The higher it is, the faster you can move on to the next stage (after about 18-25 hours).
Expanding gypsum-alumina. It is identical in properties to waterproof cement, but the peculiarity of the composition made this look more durable. Such cement is practically not used for ordinary household purposes, since its price segment is much higher than that of the previous type. The hardening of such a mixture is also several times longer, which can cause inconvenience (approximately 70-85 hours before complete hardening).
ROC (aka expanding Portland cement). Due to its complex composition, this species is one of the most durable. This cement is used to create monolithic reinforced concrete structures. The expansion of such a mixture occurs only when exposed to steam.

It is important to keep in mind that the expansion type of this product is not linear and cannot be used for the topcoat. The mixture hardens after 60-80 hours without exposure to steam and about 35 hours in the steam room.

In principle, stress cement is not used in everyday life.

The NC was created specifically for the construction of dams, water structures, they are reinforced with the finishing of water pipes.Such a mixture allows you to create heavy-duty structures, and the load for which the solution is designed does not occur in everyday life. The stress cement is completely hardened after 70 hours, but the bond is fixed after four hours.
The latest and newest type of expanding cement is plasticized. The special properties of the composition make it very convenient to work with this type, moreover, such a product is the most plastic. Practically not used in its pure form, it is mixed with concrete or plain cement. Basically, such a solution is used in the construction of work surfaces, including roads. The expansion of this cement is linear, so a final coating with this mixture is possible.

The time it takes for the cement to harden, as well as what technical characteristics it will have, depends mainly on the proportions of the main constituents of the material. In order for these points to be fixed and spelled out, the document GOST 31108-2003 appeared. It regulates the proportions of the components, which helps to avoid problems and misunderstandings during all construction work.

GOST 31108-2003 divides self-expanding compositions into 3 types:

Non-shrinking compositions are marked with NTs 10 marking;
NTs 20 are considered to be compositions with medium expansion;
Cement with maximum expansion rates is used under the NTs 60 brand.

The use of NTs 20 helps to achieve a high level of concrete strength. Expansion and tensile strengths are higher than conventional Portland cement based mortars. The water pressure withstand by concrete with the addition of NTs 20 can reach 20 atmospheres, frost resistance - up to 1500 cycles.

All of these characteristics make this type of stress cement especially in demand in various types of construction work.