How long will the foundation last if work is done to mix concrete from low-quality or fake cement? The answer is obvious.

Professional builders are large companies that constantly carry out a large volume of work, check the quality of cement in laboratory conditions and exercise strict control over the process.

There is no point in ordering and paying for a laboratory test for an ordinary buyer who needs to purchase a couple of bags for minor repairs.

And when you buy a small quantity, and when you immediately purchase a large batch that will be needed for construction, you don’t want to give your money for a fake.

Beware - fake! How can we be deceived?

Today there are a great many ways to falsify high-quality cement, because this activity brings huge profits.

Let's look at the most popular methods of counterfeiting:

1. Instead of cement they sell packaged dolomite dust. High-quality cement, in accordance with GOST, contains the so-called, the task of which is to increase its resistance to various influences of external and aggressive environments, to regulate the processes of heat generation and setting. The most commonly added mineral powder is dolomite dust.
2. Re-ground cement. A significant reduction in cost should definitely be alarming - cement that has already lost its quality is sold in huge quantities at bargain prices in huge quantities.
3. Any powder can be sold. Under the guise of cement, they sell almost any powder that looks like it in appearance - dust from electric precipitators of cement factories; ground mixtures with sand, slag, concrete waste. What they have in common is the lack of even a theoretical possibility of grasping.

How to choose quality cement

It is impossible to definitely tell by appearance what exactly they are trying to sell you. There are significant points that must be taken into account before deciding to purchase in order to avoid counterfeiting or purchasing an expired product that has lost its quality:

• High-quality cement, by definition, cannot be temptingly cheap.
• It absolutely does not tolerate moisture. If there is a mountain of bags in front of you that lie in the open air in any weather, don’t buy it. If you smell dampness, mustiness, or see damp corners in the warehouse, it’s better to look for another place. There are drips, stains, and faded writing on the packaging—this bag has lived a hard life. Look for another one.
• The quality of cement and its freshness can be determined by touch - the bags are soft, their contents are mobile, “flowing” under your hands. When caked in the corners of the package it turns to stone.
• We need to check the weight. Bags without manufacturer's markings have a dark history of origin. In most cases, they are lighter than factory packaging; sometimes this difference in weight can reach almost 10 kilograms.
• The quality of cement can also be assessed by external signs - fresh cement is homogeneous in composition, has practically no lumps, and small lumps crumble with the slightest pressure. If you are left with hard pieces with sharp, hardened edges in your hands, they are trying to sell you an expired product.
• Cement packaged in small or bulk packaging can be checked using an ordinary hammer: compacted under soft blows, it rings like a stone. The same sound is produced by any garbage, which is sometimes generously mixed in for weight.
• A bag of fresh cement always deforms when moved.

If you buy a large batch at once

If you need a large volume of cement, it makes sense to spend a little effort and time to ensure its quality. You can do a simple experiment:

1. We wear gloves to protect the skin.
2. Pour mineral water into the container - Essentuki 17.
3. We mix a small portion of the cement being tested to it - we make a cement paste.
4. We form it into a small round flat cake.
5. After 5-10 minutes, high-quality cement begins to harden. The cake will begin to warm up in your hands.
6. Low-grade cement may not harden at all even after an hour. The flatbread does not change the temperature.
7. If the cake begins to harden unevenly during the setting process and begins to crack, there are a lot of all sorts of impurities in the cement.
8. Cheap Chinese cement sets instantly, gets very hot, and then cracks due to thermal fluctuations.
9. All kinds of waste and mixtures passed off by sellers as cement will not change at all.

If you want complete, final confidence that you won’t have to regret your wholesale purchase later, do one more study: wrap the tortilla in a plastic bag, tightly packing it with a wet cloth on top.

After 3-4 days of “rest” in a warm place, real cement will turn into a solid form, without cracks or deformations.

It will make a ringing sound when tapped and will break into pieces if hit hard.

Don't be fooled

Which cement to choose—cheap or high-quality—everyone decides for himself.

The only way not to let scammers deceive you and leave you immediately without a decent amount of money, and without good cement, but with a fake in your hands, is to buy building materials only from reliable sellers, collecting reviews about their services through your friends.

When purchasing at the first retail outlet you come across, especially not a stationary one, you do not have any guarantees.

How to choose cement that meets all parameters? The quality certificate is the most reliable assistant in this. Each batch must be issued with an appropriate certificate - a bona fide seller must have a complete package of documents, which includes the brand, the date of manufacture, and weight.

The huge demand for this building material creates a corresponding supply. Its volume, as well as the wide possibilities for falsification, allow all kinds of fraudsters to feel good about themselves by supplying the market with low-quality goods, the compliance of which with the declared characteristics raises reasonable doubts.

Those responsible for construction must know that the quality of reinforced concrete products and the constructed building as a whole, its durability, seismic resistance, etc., depends on the characteristics of concrete. The proportions of mixtures must be maintained in strict accordance with established standards. Technologists, achieving the specified properties of the material, scrupulously calculate the proportions, the observance of which determines the further fate of the final product.

Precast concrete enterprises, in turn, maintain their own laboratories in which Portland cement is tested for compliance with the declared qualities. And only after that it goes into further production.

Methods of falsification

The mixture can be diluted with cheaper admixtures, such as dolomite dust, old cement that has lost its original qualities and has been ground again, mineral powder for asphalt concrete, fly ash and other substances. All of them are ballast that worsens the output characteristics of the material.

Express analysis

It refers to basic measures and takes up to 20 minutes. As a result, substances are identified that are clearly not related to the declared composition of the material. This way you can spot an outright fake. A laboratory is not needed for this, but the usefulness of such an analysis will be incomplete.

First of all, an external inspection is carried out - the homogeneity of the mixture is checked, including color, and the presence of lumps. Freshly ground cement, or material freshly removed from a cement truck using pneumatic blowing, has flow properties. The recumbent is more static. If lumps are visible in the powdery substance, they are tested for hardness. It is normal for the lumps to disintegrate with a little effort. If they have already become quite strong, this means that the cement loses its original characteristics and its activity is reduced.

The second stage is mixing a solution based on cement and mineral water with hydrochloric-alkaline characteristics. The ideal option is Essentuki No. 17. The resulting mixture acquires caustic properties and has a tendency to splash. Therefore, all operations must be carried out with gloves. Eyes must be protected with goggles. A disc-shaped mold is made from the mixture, the edges of which are thinner than the central part. If a high-quality material is chosen, the mold hardens for up to 10 minutes, and its heating is felt.

If undesirable additives are present, this process can take up to an hour, without being accompanied by heating. If the mold sets unevenly and cracks, this also indicates a counterfeit.

If everything went well, then the test itself (its inactive part) can be extended for 1-2 days by placing the mold in a bag with a damp environment. The poor quality of the material will manifest itself by the appearance of cracks. If the sample meets the requirements, then its astringent properties also manifest themselves - only shallow cracks may appear as a result of thermal changes.

Special instruments for express analysis

There are so-called conracciometers (popularly known as contractometers), which measure the reduction in the volume of the mixture during the reaction caused by the combination of cement with water. It is called hydration and as a result, the plastic mixture turns into stone.

There are also devices that measure the specific conductivity of the newly prepared mixture. This is how cement activity is determined. This is IAC-04M and similar devices.

And yet, for a real, full-fledged analysis that can give a 100%, reliable result, it takes time. And laboratory conditions. This way we can determine the strength of control samples by tracking the change in properties at different stages of solidification. But the reliability of such an analysis will be many times greater. The quality is confirmed with a full guarantee.

Laboratory quality analysis

Cement can be manufactured in accordance with old (PTs500D0, PTs400D20, etc.) and new (TsEM I-42.5, TsEM II-32.5, etc.) standards. They are checked in accordance with the requirements of GOST 310.4-81 (old) and GOST 30744-2001 (new). The latest standard corresponds to the European analogues of the EN 196 series.

The documents contain a detailed description of the process of creating samples, their exposure in appropriate conditions with the time coordinates of the start of testing. The testing procedure is also regulated, and there are requirements for the equipment used.

According to new state standards, at each stage of quality control the following are determined:

• grinding fineness;
• timing of the beginning and completion of setting;
• uniformity of volume changes during the hydration process;
• compressive and bending strength.

In this case, significant time is required only to complete the last point, since the rest are completed without adding sand. To determine the strength, a sample is first created, which is then stored in full compliance with the conditions set by GOST in the laboratory. The entire process of gaining strength takes 28 days.

There are also requirements for sand. They are set out in GOST 6139. Sand should consist of different fractions - large, medium and fine. Humidity does not exceed 0.2%.

The proportions of the solution are calculated by weight and are 1 to 3 with a water-cement ratio of ½. After the set period for hardening, direct testing begins, to which several samples are subjected to achieve greater accuracy. In this case, the average result is recorded.

At the Sebryakovsky Cement and Concrete company, laboratory tests are carried out according to the standard. Samples are used in the form of cubes 30x30x30 mm or beams 40x40x160 mm - they are cast from a mixture whose density complies with GOST 310.3. Tests begin within 24 hours after production. At this time, the molds are stored over a vessel with water. The storage temperature is 20 o C, air humidity is approximately 95%. The first result is the activity of the binder, determined after a compression test. To achieve reliable data, the following instruments are used:

• vibrating tables;
• laboratory mixers;
• various presses;
• granulometer - to determine the fractional composition;
• instruments for determining the activity of cement binder (contractometers, etc.);
• Blaine device - to determine air permeability;
• Vika device - to determine the normal thickness of cement paste;
• chambers for storing samples under specified humidity conditions;
• etc.

To provide such equipment, certain capacities, modern technologies and developed enterprise infrastructure are required. CJSC SCB can boast of all this.

But such equipment is not available for small enterprises, private companies, etc. In such cases, you have to believe what is written on the packaging, that is, the unsubstantiated statements of the manufacturer. The reliability of the supplier is checked only over time, and before this moment all sorts of troubles may occur due to the non-compliance of the raw materials used with the declared quality. Moreover, these problems can affect both the enterprise that manufactures structures from this composition and end consumers.

When selling its products, the SCB company provides a voluminous package of accompanying documents: certification documents, passports, invoices, etc. Transparent conditions and precise delivery - all this is carried out with careful adherence to deadlines, weight, brand and other characteristics.

It is no secret that cement is one of the most popular building materials in Russia in terms of sales volumes. Indeed, the cement market is huge and the demand for it is growing from year to year. Of course, this fact has already come to the attention of scammers for quite some time. They are trying by all available means to sell either low-quality cement or a “gray mixture”, which, in fact, is not cement at all.

And if large construction companies or concrete factories have their own laboratories that allow them to accurately determine the basic properties of cement (activity, grade, speed and uniformity of setting), then small contractors and “ordinary” people can only rely on the “honest word” of the seller.

Fortunately, it's not all bad. There are several ways that will help you check the quality of cement in 10-15 minutes and weed out obviously bad material.

Where does the danger lie?

So, in practice, you risk buying either stale cement, which has lost the lion’s share of its activity (and, therefore, brand strength), or a material that has nothing to do with cement. As a rule, this is mineral powder for the production of asphalt concrete, dolomite dust (filling powder fire extinguishers), newly ground cement, fly ash, etc. All these “mixtures” are gray in color, which confuses buyers. They can even set, but strength is out of the question.

How to protect yourself from counterfeiting?

The first and most important advice is to buy cement only from those sellers that you are confident in. The supplier must work on the market for at least 2-3 years. Under no circumstances take cement from your hands.

In addition, for each batch of cement, the seller must provide a full package of accompanying documents, ranging from certificates and quality passports, and ending with factory invoices for the cargo, which indicate the brand of cement, its weight, date of manufacture and shipment.

Of course, this will not help you protect yourself from counterfeiting 100%, but it will significantly reduce the risks, which is not bad.

How to determine the quality of cement?

First of all, you should “evaluate” the appearance of the cement. It is a dry, homogeneous powder of gray color - from light to dark gray, sometimes with shades of green. Fresh powder is quite heavy (much heavier than gypsum) and flows like water.

Please note that if the cement sits for a bit, lumps will form in it. If they are soft to the touch and fall apart easily when squeezed with your fingers, that's okay. But if significant force is required to destroy them and they disintegrate into solid particles with sharp edges, the cement is spoiled and has already lost the lion’s share of its activity. We do not recommend using it.

Is the appearance of the cement suspicious? Then we move on to an express analysis of its quality.

For the “experience” you will need mineral water (for example, Essentuki No. 17), a disposable plate, a plastic bag and rubber gloves (protection from chemical burns). So, we mix the cement in a plate with our water, and then from the “dough” we quickly make a “cake” with a thick middle and thin edges.

Let's look at the result:

• good cement sets immediately - in 5-10 minutes, and the “cake” itself noticeably heats up in the thick part;
• mixtures of mineral powders and other unknown ingredients do not set within 30-60 minutes and hardly heat up;
• highly diluted cement sets in fragments, with the formation of subsidence and cracks;
• Chinese cement, which is not of very high quality, sets strongly almost immediately, heats up quickly (sometimes to the point of vaporization) and often bursts due to thermal deformation;
• dust from electrostatic precipitators and other waste do not react in any way.

If the “cake” has set, wrap it tightly in a bag along with a wet rag and leave it for 1-3 days in a warm place. We evaluate the result. Good cement is hard, almost without cracks, rings when tapped and breaks when dropped. Bad - all cracked, can split into several pieces in your hands or crumble into crumbs.

Another tip - if you take cement in bags or big bags, feel their edges. Hard? This means that the cement is “stale” and should not be taken.

The 01Beton company works absolutely honestly and only with trusted cement manufacturers, so we provide a full package of accompanying documentation for each batch. We guarantee the quality of our products, so we are not afraid to reveal the secrets of its testing.

Right now you can familiarize yourself with, as well as

Portland cement as a building material is used in many operations - from pouring foundations and erecting walls to road construction and various repair work. Since the sales volume of this material is significant, unscrupulous manufacturers also appear, trying to sell counterfeits at the price of a high-quality mixture. It is clear that the use of a fake cannot ensure compliance with the performance characteristics for construction work, and therefore it is mandatory to carry out cement quality check.

How cement is adulterated

To make a fake, a high-quality mixture is diluted:

• mineral powders;
• dolomite dust;
• ash;
• crumpled old cement.

Express verification methods. Visual control

Cement quality control when used at particularly critical facilities, it must be carried out in a laboratory. But for private construction, it is often enough to conduct an express analysis, which allows you to quickly identify counterfeit goods. It is based on the properties of cement that change during storage.

How to check the quality of cement in a few minutes? You need to take a few lumps and try to crush them with your fingers. If, when pressed, the lump is soft and easily disintegrates, then the raw material is quite suitable for preparing high-quality concrete. When destruction requires significant effort or hard and sharp particles remain, the cement is damaged.

After assessing the appearance, you can carry out an additional check by mixing cement paste with saline-alkaline mineral water such as Essentuki. Please note that the mixture will be very caustic. A discoid (cake) is made from the solution - the hardening time of high-quality cement will be less than 10 minutes, and the figure will also become very hot. Falsified mixtures do not heat up and hardly set for an hour.

Also express cement analysis can also be carried out with special devices - contractometers. They monitor the reduction in volume of the water-cement mixture. There are also devices that measure conductivity and evaluate cement activity.

Laboratory testing methods

Laboratory techniques make it possible to accurately establish the compliance of cement with the declared brand and are fully regulated by GOSTs - GOST 310.4-81 or GOST 30744-2001 for old and new standards, respectively. The standards regulate procedures for determining grinding fineness, setting periods, uniformity of volume change and bending/compressive strength.

In the summer, the construction season is in full swing, and cement producers make a dazzle in the eyes. In autumn there is a peak of sales, the price for 50 kg drops to 90-100 rubles. In both the first and second cases, making a choice is quite difficult: the temptation to save money is too great. What should I do? How to check cement for quality? Read about this in the article.

Are there any verification methods available?

Cement, like other building materials, is produced in accordance with GOST. That is, the product must meet the standards established by law. There are laboratories to check quality in production. Control is carried out according to the following parameters:

• compressive strength;
• hardening speed;
• beginning of setting;
• water separation;
• content of sulfur oxide, magnesium, aluminum;
• and others.

Without laboratory equipment and specialized education, it is impossible to conduct a 100% quality check. What to do? Hope for luck and the Russian “maybe”? It's not all so sad. There are ways by which you can test cement even at home.

Methods for checking cement quality

First of all, do not risk buying material from an unknown manufacturer. There is a high probability of buying a fake that has nothing in common with the required material. If you bought cement and have doubts about its quality, pay attention to the following signs.

• The powder is light or dark gray in color, ideally has a greenish tint.
• When squeezed in a fist, it does not stick together and flows through your fingers.
• When rubbed between fingertips, it is soft (the fake is rough).
• The packaging contains information about the batch number, release date, and expiration date.

This is all you can check visually and tactilely. But you can determine the chemical properties of cement using Essentuki-17 mineral water. When experimenting, be careful: the powder, reacting with dissolved mineral salts, splashes, stains clothes and causes skin burns.

Pour ½ cup of cement into a container like a plate, add mineral water until the consistency appears like dough. Mix with a spoon (not your hands). Now the most interesting part: make a pancake of arbitrary diameter and thickness in the center of 4-5 cm, along the edges - 1 cm or “not at all”. Watch. Real cement sets instantly. The temperature in the center of the pancake is higher than at the edges. If the color of the pancake is greenish - grade D-0.

Seal the sample in a sealed bag and leave for at least an hour. Better - for 2-3 days. A cake made of high-quality cement, kept in such conditions, has no cracks, does not break (a slight ringing can be heard), and may be covered with a white coating (salt). Fake cement will set in lumps, causing cracks to form.

If you buy cement in bags, be careful what is loaded into the car. High-quality, fresh material has a loose consistency, which is why the bag sag. If it doesn't bend, take the money and leave. Do you have any doubts? Lightly hit the bag with a hammer: if the cement is caked, the hammer will bounce off.