Determination of concrete grade by destructive method. Methods for controlling uncured solution. Production and processing of samples

Today, there are two types of concrete tests for strength: destructive (laboratory) and non-destructive ("field"). We consider each of the types of tests separately.

Destructive methods

The most commonly used method is “standard samples”. This is one of the most accurate methods for determining the "brand" strength of concrete. The essence of the method is as follows - simultaneously with the pouring of the structure, concrete samples of cubic or cylindrical shape are made. After the sample has solidified, it is mounted on a laboratory test press and loaded until it is completely destroyed. The value of the mechanical load, in kg / cm2 or MPa, at which the destruction occurred, is the real strength of a concrete.

A less popular method is the “drill core method”. The essence and technology of the method are similar to “standard samples”. The difference lies in the fact that a sample (core) drilled from a real concrete structure is subjected to destruction on the press. Despite its accuracy (not a sample filled in laboratory conditions, but the concrete structure itself is tested), the method is not widely used due to the high cost and complexity of drilling cores, and also because of the danger of destruction of the tested product.

Nondestructive methods

• Plastic deformation. Allows you to determine the strength of concrete in the range of 5-50 MPa. With this method, the strength of concrete is determined by the diameter of the imprint of the steel ball remaining after hitting the ball on its surface. The method has little accuracy. Therefore, despite its simplicity and cheapness, it is rarely used;
• Elastic rebound. The range of measured strength is similar to the method of plastic deformation. The essence of the method is to measure the parameter of the return rebound of a special impactor from the surface of the tested structure. The main advantages are low cost and high accuracy of measurements;
• Impulse-shock method. Allows you to determine the strength of concrete in a wide range from 50 to 150 MPa. The essence of the method is to measure the impact energy of a special elastic body on a concrete surface. Among the advantages: compact measuring equipment, simplicity, low cost and the ability to calculate the reliability of concrete "compression". One of the most popular methods for measuring concrete strength in Russia;
• Ultrasound procedure. Allows you to check not only a single surface, but the entire structure as a whole.
• The technology of "chipping ribs." The range of measured values \u200b\u200bis from 10 to 70 MPa. With this method, the force that is required to shear the ribs of a concrete structure: beams, piles, lintels or columns is measured. The method is characterized by high accuracy, laboriousness and inability to use for concrete structures   with damage or structures having a protective layer up to 22 mm;
• Breakaway with chipping. Measurement range from 5 to 100 MPa. The bottom line is that a special anchor embedded in the thickness of concrete acts on the structure until the sample is torn off or the specified strength of the item being tested is set. It features a high degree of accuracy and increased labor intensity;
• Detachment of an iron disk. Strength measurement range from 5 to 60 MPa. Allows you to check reinforced concrete to which it is impossible to apply other control methods. The essence of the technology is to measure the load that must be applied in order to tear off the glued steel disk from the concrete surface. It features high accuracy and a long preparatory period - from 4 to 22 hours.

Our construction laboratory provides its customers with a wide range of services. One of them is testing concrete samples. In particular, we propose:

• test of concrete by non-destructive methods for strength incl. separation with chipping and elastic rebound;
• concrete strength test - determination of the strength characteristics (concrete strength) of structures by destructive methods for samples made from concrete mix and samples taken from the body of structures; (drilling)
• determination of water resistance of concrete mix in structures and samples;
• determination of physical and mechanical characteristics of sand and gravel;
• concrete test for frost resistance, including accelerated methods;
• selection of concrete mix and mortar

We are equipped with all necessary modern measuring instruments and equipment. Among other things, we have:

• bursting machine;
• press (testing concrete samples for compression);
• climatic chamber for testing concrete for frost resistance;
• installation for core drilling;
• a device for determining the location and diameter of reinforcement without breaking structures.

Also in the arsenal of tools are instruments for determining water resistance, ultrasound systems for monitoring the strength of concrete and the quality of welds, devices for determining the strength of concrete by non-destructive methods (Schmidt, separation with spalling, etc.). The equipment with which concrete is tested for compression and other operations undergo systematic metrological verification.

We provide services for testing building materials:

• we will test bricks, concrete blocks of light and heavy concrete;
• determine the presence of reinforcement in concrete structures, diameter and its location;
• we determine the strength of the mortar in the structures and seams of the masonry with a destructive and non-destructive method.
• physical and mechanical tests of samples of reinforcement and welded joints,
• visual-instrumental and ultrasonic quality control of welds;
• determination of the density of the bases from the soil;
• determination of the force of separation of the anchor from building structures;

Using these services, you get the opportunity to significantly improve the quality of construction work and the economic efficiency of construction.

At present, concrete mix is \u200b\u200bthe main building material widely used for supporting and enclosing structures of residential, civil and industrial buildings, as well as for the construction of various structures: bridges, roads, etc. Therefore, the relevance of obtaining a durable and reliable composition is obvious. To achieve this, laboratory tests of concrete samples (concrete strength) are necessary. They allow us to guarantee the compliance of the composition with the declared properties.

Laboratory tests of concrete are performed to confirm its actual condition with design quality parameters. Examination of concrete quality is carried out in several stages by various types of control, depending on the stage of installation of structures.

How can you save on the services of a construction laboratory?

1. Correctly "hammer" concrete cubes. We often encounter errors when pouring cubes, such as: incorrectly laid in the mold, improperly compacted, violated storage conditions (left on the street, concrete was frozen, it did not “grapple”), the construction laboratory will receive incorrect concrete strength test results, etc. Consequence: additional visits of the construction laboratory for rechecking, repeated testing of concrete and your spending money to pay for these visits. The “clogging” technology is described in detail in GOST 10180-2012 “Methods for determining the strength of control samples”.

2. How to check concrete without a laboratory - a cheat sheet for foremen. When the next batch arrives in the “mixers”, check on your own the workability of the concrete mixture. This simple method will give you an initial understanding of the quality of incoming concrete. Laboratories perform this test according to GOST 10181-2014 “Concrete mixtures. Test methods. "

3. Optimize the number of trips. GOST 18105-2015 "Concrete rules of control and strength assessment" requires to test the strength of concrete according to cubes or non-destructive testing methods on the 7th and 28th day. A number of customers unreasonably call a construction laboratory for each removal of formwork. This is done only if the project has a direct indication of the expertise of the formwork strength of concrete (i.e. it is necessary to make measurements between 7 and 28 days). And each trip to the construction laboratory costs money. Additionally: combine close “age” types of tests and save time and money on the challenges of the construction laboratory.

4. Prepare the site in winter. During the “separation with chipping” to accelerate the work of the construction laboratory for the arrival of laboratory engineers, prepare a burner (gas cylinder), an extension cord for heating the structure in the test zone, as otherwise the frozen concrete will give incorrect indicators or the construction laboratory specialists will stand idle without work while you are doing these preparatory work.

5. Be attentive to documents. Be attentive to the documents for the incoming batch of concrete. We found concrete grade B22.5 where the design should have B30. The reason, as it turned out: concrete was shipped from the plant to different facilities and the operator mixed up the recipients of this batch. As a result, it was not B30 that came to the site, but B22.5 and, without checking it, they put it into operation. Swearing, screams - reinforcement of constructions, unplanned spending of money by a construction company.

One type of classification of concrete: by volumetric mass (heavy and light). Laboratory control of the quality of lightweight concrete (density less than 1800 kg / m3) is carried out to match its actual density, strength, frost resistance, other design parameters. Tests are carried out on control samples (for example, cubes - “cubes”, which destroys the type of tests on the press) selected from structures or other acceptable standards for this type of structures methods.

In the case of work with heavy concrete (density more than 1800 kg / m3), the examination of concrete is carried out including according to the parameters of compressive strength, frost resistance and water resistance.

What to do with the determination of concrete parameters in an already mounted structure? The so-called destructive laboratory methods of examination are no longer suitable here (testing the “cubes” of concrete in the press). For this situation, concrete quality control is carried out by indirect methods: separation with chipping, "ultrasound" of concrete, sclerometer ("elastic rebound") - non-destructive methods.

We carry out concrete tests with non-destructive testing methods: separation with spalling, impact-impulse, ultrasonic methods, cubic strength test.

№	Types of jobs	Test method	unit of measurement	Cost, rub.)
1. Monolithic concrete and prefabricated reinforced concrete structures and products
1.1	Determination of concrete strength in structures by tear-off with chipping	GOST 22690	1 test	800
1.2	Determination of concrete strength in structures by ultrasonic method	GOST 17624-87	1 plot	250
1.3	Determination of concrete strength in a structure by elastic rebound method, shock impulse	GOST 22690	1 plot	250
1.4	Determination of concrete strength by samples taken from structures	GOST 28570-90	1 sample	250
1.5	Determination of humidity of a concrete structure	GOST 21718-84	1 dimension	500
1.6	Rebar positioning	GOST 22904	1 dimension	500
1.7	Determination of the thickness of the protective layer of concrete	GOST 22904	1 dimension	500
1.8	Building a calibration dependence	GOST 22690,	1 view	4 500
		GOST R 53231-2008
1.9	Correction of the calibration dependence		1 view	1 500
2. Concrete mixtures
2.1	Strength test for compression of concrete samples - cubes	GOST 5802	1 sample	250
		GOST 10180
2.2	Bending and compressive strength test of concrete blocks	GOST 310.4	1 sample	150
		GOST 10180
2.3	Determination of concrete temperature		1 test	50
2.4	Concrete mobility	GOST 10181-2000	1 test	300

Strength testing of concrete at the Tehlabkontrol laboratory will allow you to be sure of the objectivity of the strength characteristics of concrete and the commissioning of the facility to the Customer.
We guarantee our customers professional testing in Moscow and the Moscow region.
All tests are carried out strictly in accordance with the provisions of GOST and other guidelines.
Our laboratory has many years of experience in laboratory testing of concrete, equipped with high-precision modern equipment. This allows you to get the most informative, reliable and objective data. Research can be carried out both at a construction site and in a concrete testing laboratory. We test concrete samples in a complex or do tests for individual parameters.

Targets and goals:

Our laboratory tests concrete for strength in order to determine the optimal composition of concrete and its strength characteristics to meet high performance parameters.

The main characteristics of the reinforced concrete mixture are determined in any construction process with the active use of concrete components. The main objective of the study is to verify the performance of the hardened mortar, the strength of concrete is one of the key indicators.
Testing control samples of concrete or a finished monolithic structure provides the necessary operational safety.
When concrete tests are needed:

• when checking the quality of the material and construction work for compliance with design and regulatory documents;
• in case of suspicion of the presence of internal defects in the reinforced concrete structure;
• before work on raising the floor in technical and basement rooms;
• with the penetration of water and violation of the tightness of the basement;
• when external damage and cracks appear in a monolithic structure;
• if necessary, assess the characteristics of the concrete structure before purchasing the object;
• before starting work on major redevelopment and reconstruction of the building.

Timely testing and taking measures to prevent and repair structures will prevent possible structural destruction. Making a decision to carry out repairs in the future will help reduce the cost of repairing serious damage. We are also engaged in the repair of reinforced concrete structures. For more information, please call us at the telephone number indicated on the website.

Testing.

Concrete strength control is the most important parameter during testing. To do this, laboratories test cubes or cores of concrete drilled from the structure. Samples are taken from the batch of the mixture at the intermediate and design age (28 days).
In cubes, the dimensions of the ribs are 100, 150, 200 or 300 mm.
For cylinders, the diameter is 100, 150, 200, 300 mm, and the height is two diameters.
For the manufacture of samples, special metal forms are used with cells having an inner rib of 100 mm in size. In the manufacture of samples, standardized sizes are provided. The manufacture is carried out as follows:

1. A sample of the mixture is taken from the middle of the batch (when using a concrete pump - in 3 doses in 10 minutes with stirring before laying).
2. The mixture is laid and compacted no later than 20 minutes after selection and not higher than 100 mm of the layer height. With a cone draft of more than 10 cm, laying is done by bayonet. With a smaller OK, vibration is additionally applied.
3. Prepare a series of samples for testing (3-4 pieces in a series) under the same conditions. The permissible deviations of the average density at the time of testing the concrete cubes do not exceed 50 kg / m3.
4. Defective samples are taken. Before testing concrete cubes for strength, remove those from the series in which there are foreign inclusions, shells, chipped ribs, cracks, areas of weak compaction and delamination (except for large-porous concrete).
5. Testing concrete samples for compression or strength is performed in the number of batches of material at the design age equal to 28 days, regulated by clause 5.2. GOST 18105.
6. Incoming control requires special storage conditions for samples (air humidity 95%, temperature - +20 degrees). Permissible deviations of humidity - 5 percent, temperature - 3 degrees.

Tests are carried out using different methods that are optimal for determining a specific parameter. Among non-destructive research methods are the use of ultrasonic sounding, elastic rebound, shock impulse, separation with chipping. Sometimes combined testing methods are used. Based on the results of the tests, an official expert opinion is drawn up.

The document contains:

• research results;
• evaluation of concrete mix parameters;
• recommendations for the operation of the structure or the use of concrete.

The document confirms the suitability or unsuitability of concrete and the possibility of further operation of the structure. The recommendations are aimed at improving the quality of the concrete mixture, changing its composition, eliminating structural defects or stopping the operation of the facility.

We provide hosting services concrete test. All material tests are carried out in strict accordance with applicable normative documents RF (GOST, SNiP, SP). When conducting concrete tests, parameters such as:

• Strength (according to samples and designs);
• Density;
• Water resistant;
• Frost resistance;
• Location of reinforcement in structures and the thickness of the protective layer;
• Humidity.

№ p / p	Test Name	Normative document	Price per one. tests in rubles
Testing concrete (mortar).
1	Determination of the strength of one sample in compression (10x10x10 cm).	GOST 10180-2012	250
2	Determination of the strength of one sample solution in compression (7x7x7 cm).	GOST 5802-86	250
3	Drilling, preparing and testing core samples from structures.	GOST 28570-90	3000
4	Determination of concrete strength by samples taken from the structure (core).	GOST 28570-90 GOST 10180-90	500
5	Determination of the strength of the masonry mortar from samples taken from the structure.	GOST 5802-86	3000
6	Strength determination by non-destructive method on the construction site (method: elastic rebound, ultrasonic testing).	GOST 22690-88 GOST 17624-2012 GOST 18105-2010 GOST 31914-2012	300
7	Definition of the actual class in a separate design (6 sections).	GOST 18105-2010 GOST 31914-2012	1000
8	Determination of strength in the structure by peeling with chipping.	GOST 22690-88	1000
9	Construction of a calibration dependence between strength and indirect characteristic (elastic rebound, ultrasonic testing).	GOST 22690-88 GOST 17624-2012	12000
10	Determination of average density from samples.	GOST 12730.1-78	500
11	Determination of surface moisture (screed).	GOST 12730.2-78 GOST 12730.0-78 GOST 21718-84	500
12	Determination of water tightness in a design and products.	GOST 12730.0-78 GOST 12730.5-84	500
13	Determination of water resistance in a series of samples (6 pcs.).	GOST 12730.0-78 GOST 12730.5-84	2500
14	Determination of frost resistance in a series of samples. (6-12-18 pcs.)	GOST 10060-2012	35000
15	Determination of the thickness of the protective layer and the location of reinforcement in the structure and products. Uch. 2-3 m 2.	GOST 22904-93	1000
16	Determination of the adhesion strength of the mortar (screed, plaster) with the base.	GOST 28089-2012 GOST 28574-2014	2000
17	Sampling of concrete mixture with the manufacture and storage of samples in a chamber of normal hardening.	GOST 10180-2012	1200

The main standardized and controlled quality indicators during construction in accordance with SNiP 52-01-2003 "Concrete and reinforced concrete structures" are:

• Compressive Strength Class B;
• Axial tensile strength class Bt;
• Frost resistance grade F;
• Waterproof Brand W;
• Grade by average density D.

Concrete strength.   The main requirements for reinforced concrete structures, in modern construction, is the consistency of strength inherent in the project. The strength of concrete can be determined both in laboratory conditions (test samples) and on a construction site (non-destructive testing methods):

• Strength test (concrete compression test) (GOST 10180-2012).The essence of the method is to determine the strength and consists in measuring the minimum effort that destroys control samples of concrete under their static loading. During concreting, concrete cubes are made from the concrete used, or core samples are drilled directly from the structures themselves (GOST 28570-90).
• Nondestructive methods   tests (GOST 22690-88, 17624-2012).   The strength of concrete is determined by a pre-established calibration relationship between the strength of concrete (determined on samples or by tearing with chipping) and an indirect characteristic. An indirect characteristic, depending on the test method, is: values \u200b\u200bof elastic rebound, shock impulse, separation with chipping, chipping ribs, ultrasonic method. Non-destructive methods make it possible to determine the strength in a structure without damaging it and reducing its bearing capacity.

Workability of concrete mix (101810-2000).   This method characterizes the indicators of mobility and stiffness of the concrete mixture. BS mobility is assessed by sediment (OK) or the spread (RK) of the cone formed from the test mixture. To conduct this test, a steel cone, bayonet, ruler and stopwatch are used. Depending on the test results, the brand of concrete mix is \u200b\u200bdetermined by mobility or stiffness.

The density of the concrete mixture (10181-2000).   The essence of the method lies in the ratio of the mass of compacted concrete mixture to its volume. During this test, the concrete mixture is placed in a pre-weighed vessel and compacted depending on the workability. The average density is defined as the arithmetic mean of two determinations from one sample.

Testing concrete for frost resistance (GOST 10060.0-2012).The essence of the method is a comparative analysis of the strength of concrete samples between control samples and samples that have passed a certain number of freezing and thawing cycles. This method allows you to determine whether a given concrete meets the required class of frost resistance (F). Tests are carried out in laboratory conditions on a series of concrete samples using freezers (-20 ... -50 C) by alternately freezing and thawing the concrete. The method is divided into several types of tests: basic and accelerated. Depending on the method for determining frost resistance, the number and size of samples should be taken according to Table 2 GOST 10060.0-2012.

Water tightness of concrete structures (GOST 12730.5-84)   The main method is an accelerated method for determining the water resistance of concrete by its breathability. This method can be used both in laboratory conditions (on samples) and in structures using an Agama -2P type instrument. This type of test is especially significant for hydraulic structures (pools, reservoirs) and shows which concrete class belongs to waterproofing (W).

The main GOSTs used in concrete testing:

• GOST 10181-2014. MIXES CONCRETE. Laboratory Test Methods for Concrete
• GOST 12730.1-78. CONCRETE. Density determination methods.
• GOST 12730.2-78. CONCRETE. Method for determining moisture.
• GOST 21718-84. Building materials. Dielcometric method for measuring humidity.
• GOST 53231-2008. CONCRETE. Strength control.
• GOST 22690-88. CONCRETE. Determination of strength by mechanical methods of non-destructive testing.
• GOST 10060.0-2012. CONCRETE. METHODS FOR DETERMINING FROST RESISTANCE.
• GOST 12852.0-77. CELLULAR CONCRETE. General requirements for test methods.
• GOST 28570-90. CONCRETE. Methods for determining the strength of samples taken from structures.
• GOST 17624-2012. CONCRETES. Ultrasonic method for determining strength.
• GOST 22904-93. REINFORCED CONSTRUCTIONS. MAGNETIC METHOD FOR DETERMINING THE THICKNESS OF THE CONCRETE PROTECTIVE LAYER AND THE LOCATION OF THE REINFORCEMENT.
• GOST 10180-2012. CONCRETE. Methods for determining the strength of control samples.
• GOST 12852.6-77. CELLULAR CONCRETE. Method for determining sorption moisture.