How to check the quality of concrete in the liquid and solid

With active work with building mixtures, sooner or later one has to learn to identify certain characteristics by visual signs or with the help of special devices. If necessary, the quality check of the concrete can be carried out both in the liquid state and in the hardened state, when the structure is completely ready.

Determination of parameters of the liquid mixture

Immediately before pouring the freshly prepared solution, it is recommended to make sure of the technological properties, especially if the batch was done by hand or the manufacturer does not inspire confidence. By completing an independent control, you can learn a lot about the quality of products.

Density check

Having calculated the approximate mass of a substance in a certain unit of volume, one can judge which category this composition belongs to. This parameter is particularly influenced by the type of placeholder. Detailed information on the density of the mixtures is presented in the table.

Attention! The first two categories of solutions are mainly used to form an additional layer. However, in some cases with their help small structures can be created.

Immediately before testing it is necessary to carry out preparatory activities. For the work will require: a two-liter capacity, trowel, scales and metal rod for compaction. The used container is immediately weighed, after which its volume is determined in cubic centimeters.

Next, the mixture is applied with a trowel in the prepared dishes to the brim. Armature pin is made of a bayonet. After the compaction process, the surface of the concrete solution is leveled by cutting off the excess.

The filled container is weighed with an accuracy of up to a gram.

1. First, the net mass of the mixture is determined., for which the weight of the applied tare to check is subtracted. Example: 5000-400 = 4600 g.
2. Then the result is divided by the volume of a two-liter vessel.. The result is: 4600/2000 = 2.3 kg per 2000 cm3.
3. At the last stage of the calculation, it remains to find out the density in one cubic meter.: 2,3×1000=2300 кг/м3.

Note! The density of the composition can be increased by proper selection of aggregate, reducing the amount of water, as well as high-quality vibration using special equipment.

Stiffness testing

From this parameter depends not only the ease of installation, but to some extent, the strength characteristics of concrete. Officially, the test is carried out using a special device according to GOST 10181.1-81. The device is a cylindrical metal vessel.

In the process of determining the stiffness of the product is fixed on the vibration platform with an amplitude of movements of 0.35 mm and a frequency of 2800 to 3200 vibrations per minute. The final indicator is the arithmetic average number of two determinations taken at once from the same sample.

However, the price of such equipment is quite high, so individual developers are not able to conduct research in this way. Therefore, you can use the simplified version, which provides for the presence of a single vibrator.

The cubic shape, having an edge of 20 cm, is mounted on a vibrating table and fixed in one position. In it the standard cone intended for filling with solution is located. Vibration continues until the liquid composition is distributed horizontally. The value is determined using a stopwatch.

Mobility assessment

Testing is carried out using a standard cone made of galvanized iron or sheet steel. The amount of precipitation of this object characterizes the mobility of the solution. If the figures are too low, water and a binder are added.

Control of hardened material

The most accurate assessment of the quality of concrete is made after its final solidification, when 28 days have passed since it was poured. Control can be destructive and non-destructive. In the first case, a direct sample is taken, and in the other, testing is carried out with various instruments, the readings of which are not absolutely accurate.

Non destructive methods

• Separation of the disks involves the removal of tension, which is produced during local destruction. The applied force in this case is divided by the quadrature of the surface projection.
• Cleavage of the ribs allows you to define the characteristics of linear structures such as columns, beams and piles. The method cannot be used if the protective layer does not exceed 2 cm.
• The separation with chipping is the only non-destructive testing method for which calibration dependencies are officially regulated. When testing it is possible to achieve high accuracy.
• Ultrasound quality testing involves determining the speed of passage of waves. Distinguish through and superficial sounding. The difference lies in the location of the sensors.

• Elastic rebound provides an opportunity to measure the amount by which the drummer will move after exposure to the surface of the structure. Tests are carried out using spring hammers.
• Shock impulse allows you to register the energy of the perfect blow, which is formed when the striker touches the plane. Such devices are compact in size.
• Plastic deformation is based on measuring the dimensions of an imprint left after an impact with a steel ball. The method is a bit outdated, but it is still used, which is connected with the cheapness of the device.

Destructive methods

• The cutting of the sample from the concrete structure is carried out by special equipment of the type URB-175, equipped with a cutting tool like diamond discs.
• Drilling is carried out using drilling machines such as IE 1806. They have a diamond or carbide drill.

As a conclusion

Before you buy the finished composition from the manufacturer, you need to find out if he has a quality certificate for concrete. This is not a prerequisite, but gives an idea of ​​the reliability of the company's intentions. More detailed instructions on the topic are reflected in the video in this article.