M400 cement: composition and use
Very often, during construction and finishing works, M400 cement is used. This is a versatile material: it has good strength, it is convenient to work with it, and the finished product has a good appearance and durability. However, not everyone knows what lies in the labeling of this cement.
This mixture belongs to the category of Portland cements, therefore it often has the letters “PC” in its designation. It is named after the town of Portland in the UK, because it resembles in appearance the natural stone mined there.
The number 400 is an indicator of the maximum strength of a cement product. Marking M400 means that a product made of it is capable of withstanding a compressive load of 400 kg per 1 cm3.
The letter D with the number following it denotes the presence and quantity of additives that improve the various characteristics of the cement. The figure shows the percentage of additives in the bulk of the clinker.
According to the new GOST 31108-2016 "Cements for general construction", the product of this brand has a more detailed designation: it contains information about the presence of additives and their form, as well as the class of strength. For example, the cement grade CEM II / A-P 32.5 indicates the presence of clinker in the amount of 80-94%, as well as mineral additives in the form of pozzolan. The figure at the end of the mark means compressive strength of at least 32.5 MPa at the age of cement for 28 days.
Types and characteristics
Despite the fact that the GOST for building cements, issued instead of GOST 31108-2003, implies a new designation of brands of building mixtures, many are still guided by the old numbers and letters. Therefore, manufacturers, seeking to facilitate consumer choice, indicate on the packaging the following labeling:
- M400 D0 - does not contain any additives and consists only of clinker. This mass is characterized by high frost resistance, medium solidification rate and deformation during shrinkage. As a rule, it is a mixture of general construction purposes.
- M400 D5 - contains up to 5% of additives that improve the water-repellent properties of the product and increase the resistance to corrosion. It is recommended for the construction of supporting structures and floors.
- M400 D20 - it contains up to 20% of active additives, allowing it to be used for both residential and industrial premises. Such cement is used both in Russia and in Europe. It has a very good frost resistance and is excellent for underwater structures, as it is waterproof.
Oddly enough, but an increase in additives in cement leads to a decrease in its value. The most expensive is the brand M400 D0, and a more budget option - M400 D20.
There are also specific types of cement that give the product the desired properties. For example, a sulfate-resistant composition that allows the use of cement products in corrosive environments and mineral waters. Products with such cement have a very high resistance to aqueous media. Such mixtures can be distinguished by SS marking in the brand name.
Another example is the expanding cement, indispensable for repairing cracks in walls, as well as when gluing pipes in mines and tunnels. It fills cracks and seams and contains additives that, when dried, increase the volume of the mixture. This restores the integrity of the product.
Sometimes, alumina cement is needed for work.It is characterized by rapid hardening - the calculated strength is achieved on average in 7 days.
Its other feature is low ability to deformation, and also fire resistance. Typically, this type of mixture is used for quick installation of foundations, as well as for the repair of underwater structures. For quick-drying cements use an additional letter "B" in the labeling.
Of course, the specificity of the additive always leads to an increase in the price of cement. However, one should not forget that such additives are used in small quantities and their use is economically justified.
The characteristics of the cement are affected by the conditions and shelf life after production. For example, the bulk density of fresh cement depends on the degree of grinding, but on average is 1000-1200 kg / m3. If, however, the cement is stored in conditions that do not comply with the manufacturer's recommendations, then it will be packed to a density of 1700 kg / m3, and at high humidity it can weigh up to 3000 kg per cubic meter. This can lead to premature hardening or loss of strength properties of concrete. Instead of a mass for active chemical interaction, you get an inert mineral crumb.
Cement with a weight up to 50 kg in strong paper bags is on sale. The package clearly indicates the brand mix, recommendations for use, as well as the batch number and date of production. It is the freshness of cement that guarantees the quality of future products. Therefore, you should choose packaging with a later release date.
Looking at the production date, it should be taken into account that every 3 months the cement loses about 15% of its original properties. If, however, old cement is still used in construction, it is necessary to provide for its increased consumption to obtain concrete of a given strength.
Also sold and bulk technical cement. It is more convenient to purchase it for large volumes of work. Its cost is 15-20% lower than packaged. This is due to the lack of packaging, and with large volumes of purchases. However, the bulk mix is more difficult to track the date of manufacture, and, consequently, the quality of the source material.
Cement production plants are located in almost every region of Russia. The proximity to the manufacturer will significantly reduce the cost of transporting large quantities of cement.In addition, at regional plants, various substances are added to the cement, which improve the physical and mechanical properties of the structures, taking into account the peculiarities of the weather and water conditions of the area.
Here are some examples of businesses located in different regions:
- Yakutcement Association - Republic of Sakha.
- Podolsk cement plant - Podolsk, Moscow region
- Teploozersk cement plant - Jewish Autonomous Region.
- Novotroitsk Cement Plant - Orenburg region, Novotroitsk.
- Verkhnebakansky cement plant - Krasnodar region, Novorossiysk.
There are dozens of similar enterprises. There are on the market and major manufacturers, known throughout Russia and even in Europe. For example:
- "Mordovtsement" offers brand 400D20 in bags of 40 kg. This product has a high corrosion resistance and it is more frost-resistant. The average price is 200-230 rubles.
- Eurocement combines a group of industrial enterprises, therefore, offers a wide range of products. M400 cement can be bought in packages from 25 kg to 1 t. The price is about 220 rubles. for 50 kg.
Scope of application
M400 - cement universal brand. It is used in the construction of low-rise buildings, underground and underwater structures, for plastering and finishing the external and internal walls of premises. The main advantages of this mixture are:
- Ease of operation and low requirements for breeding and use. It is enough to follow the instructions on the manufacturer's packaging to get a quality solution and a good surface of the finished product.
- The relatively low cost of the mixture and its availability. You can buy an M400 bag in any building department; complexity can arise only when choosing one of the many manufacturers.
- Good operational durability of products. Even if small deviations were made from the technology of preparing or laying cement, cracks on the surface are unlikely to occur.
- The temperature range in which concrete products can be operated without damage - from -60 to + 300C, which provides the widest range of applications of this brand of cement.
- Minimal shrinkage during curing. This very important property will allow not to be mistaken in sizes when filling the base or production of any other product. Also, a small amount of shrinkage ensures no cracks on the surface of the product.
- The cement of this brand quickly hardens.Hardening time is sufficient to complete all work with the mixture (mobility is lost after about 6 hours), but the product gains its final strength in a couple of weeks. As the temperature or humidity rises, the curing reaction of concrete from cement M400 accelerates.
- The ability to use different additives gives the mixture flexibility, corrosion resistance, the ability to harden more quickly and other useful properties.
However, with all the benefits of this cement, it should be remembered that for the construction of multi-storey buildings and structures bearing increased load, it is better to use more durable brands (for example, M500).
Tips for using:
- To prepare a concrete solution, it is necessary to dilute the cement with water in a ratio of 2: 1, that is, the mass of water is about half the weight of cement. Water should not have impurities, dirt, branches and large inclusions - this will reduce the strength of the finished concrete. And it is very important not to add water to the already prepared mixture.
- The remaining components of the mortar - crushed stone, sand and filler - must also be free from dirt and uniform in size.Crushed stone is better to use two fractions - large and small, this will give concrete additional strength.
- No need to buy cement long before the work. In a warehouse of the manufacturer or supplier, as a rule, proper storage conditions for the mixture are provided - temperature and humidity are controlled. Keeping the same at home or in the garage does not guarantee the same conditions. In addition, the shelf life of cement M400 small - usually from 6 to 12 months. Increased humidity may adversely affect the strength of the cement and the quality of its mixing in concrete.
- There are approximate values of cement consumption: for example, to obtain 1 m3 of concrete, it is necessary to take from 180 to 260 kg of material M400, depending on the required strength of the final solution. Recommendations on the packaging will prompt more accurate values.
- Determining the consumption of cement, it is important to take the material 10-15% more from the calculated amount. It is advisable to buy material from one batch and from one supplier and immediately use it for its intended purpose. You can ask the seller to return the excess cement.
- Mix that volume of concrete that will be consumed in the next few hours, before the mixture hardens.Re-dilution of the frozen mixture with water is useless, since chemical hardening reactions will already occur in the mixture.
How to choose the right cement, see the video below.