Prediction of concrete final actual strength

FIELD: instrumentation.

SUBSTANCE: invention relates to prediction of final actual physical strength of concrete. This method comprises conductimetric measurement of specific electric resistance and temperature of mortars in their hardening in real time and evaluation of actual mechanical compression strength of preset type of concretes. The following process parameters are controlled: start of motor hardening and concrete specimen strength at 28-day age. Duration of measurements makes 100-125 min from mortar filling into container pickup till termination of hardening induction period. In said range parallel measurements of specific electric resistances of mortar specimens are performed for calibration and design minimum compositions. Correlation dependence between specific electric resistance and actual mechanical strength of concrete of preset type at design age is set. Results of analysis of variation in specific electric resistance in said range are used for control over of early hardening of said motor of preset concrete type to evaluate actual mechanical compression resistance of concrete.

EFFECT: higher quality of evaluation.

5 dwg, 6 tbl

 

The invention relates to methods of assessing the development status of cement-concrete mixtures in the process of curing and hardening in real time and predict the final actual concrete strength.

In the modern monolithic construction and wide application of precast concrete and concrete structures of buildings and structures non-destructive testing the ultimate strength of cement-concrete systems is one of the most important conditions for improving the quality of products based on mineral binders, as well as the intensification of their production for energy and resource saving technologies.

Methods of nondestructive testing of concrete systems, including the use for measurement of electrical quantities converted to direct evidence, defined in GOST 27005-86. These methods apply only for the control of products and structures made of concrete, under construction and durability, these methods are time-consuming (not earlier set of samples of examinees 28-day strength) and quite time consuming, which does not allow them to apply for quick adjustment of technological processes of casting.

From the description of the patent RU №1742702 A1, 24.07.1989 for "Device for measuring the potential of mass transfer material" known electrophysical method of controlling the solid�" binders using Akhmetzhanova sensor. In this method, produce a conductivity measurement the conductivity of the samples binders in liquid state, which can be downloaded in an electrolytic cell. In the process of measurement records the time of hardening and mass transfer potentials of the base and examined samples of Portland cement in a given time interval, but the resulting indicators of hardening in the first two hours of measurements is insufficient to predict the ultimate strength of concrete, because this method does not propose the establishment of a correlation between strength of concrete and the values of mass transfer.

In its technical essence and the achieved result is the closest analogue is the prototype of the present invention is a method of control of technological parameters and predict the final actual concrete strength, including conductometric measurement of electrical resistivity and temperature during the curing of the samples of concrete mixes in real time with the subsequent evaluation of the actual mechanical compressive strength of concrete samples of a given class (US No. 7225682 B2, 05.06.2007).

The known method, as proposed, based on the choice for measurements of electrical resistivity as an electro-physical quantity. In known�om method the interval of real time, which produce the necessary measurements is not less than 50 hours, i.e. more than one day. This circumstance given the fact that each cement concrete composition has its own special properties, defined by the set of process parameters (type of cement, concrete mixture, the conditions of transport), does not allow to create objective method of accelerated evaluation of process parameters and the actual ultimate compressive strength of samples of concrete of a given grade and structural concrete products.

The object of the invention is a rapid prediction of the actual ultimate strength of the concrete, the possibility of rapid adjustment of the technological process of casting, and prerequisites for the reduction of energy costs and material resources.

This problem is solved in that in the method of predicting final actual concrete strength, including conductometric measurement of electrical resistivity and temperature during the curing of the samples of concrete mixes in real time with the subsequent evaluation of the actual mechanical compressive strength of concrete samples of a given class, produce a parallel measurement of the specific electrical resistances of the samples of concrete mixtures calibration and calculation �ratings of compositions and establish the correlation between electrical resistivity and the actual mechanical strength of concrete of a given class in its design and age and the results of analysis of changes in electrical resistivity of the specimen concrete mix specified composition of a given class of concrete in a time interval equal to 100-125 minutes after pouring in the sensor container type specimens of both concrete mixes, provide control of early hardening of the samples of the concrete mix specified concrete grade and end-actual mechanical strength of concrete in compression.

The invention consists in the following.

As you know, the hardening of binders, in particular cement, included in the composition of concrete mixtures, during their interaction with water is based on the unique phenomenon of conversion of the starting material is hydrated in tumors of different composition. This dramatically increases the amount of the solid phase compared with the original volume of the binder (A. V. Volzhensky. Changes in absolute volumes of the phases in the interaction of inorganic binders with water and their influence on the properties of the formed structures. // Building materials, 1989, No. 8, p. 25). Hydration, i.e. the interaction of particles of the original substance with water, consists of physico-chemical dispersion (the actual chemical reaction of formation) hydrates complicated for polymineral binders real conditions of the processes, due to the mutual influence of mineral�in and phenomena of adsorption, diffusion, etc. and create patterns with defined physico-chemical properties.

The mechanism of hardening (hardening) of mineral binding materials and concretes - a series of successive stages-transitions of a system from one structural state to another.

The first stage of the hydration process is characterized by short exothermic reaction. The duration of this stage depends on the type of binder and includes several elementary acts (N. B. Ur'ev. Highly concentrated dispersed systems, M. ed. Chemistry, 1980, p. 320), which occur on the active sites of the surface of the original binder. The concentration and nature of active sites determine the intensity of the initial interaction of the binder with water (M. M. Sychev, Some questions chemistry interparticle condensation hardening cements. // Cement, 1982, No. 8, pp. 7-9).

The second stage of the hydrate formation induction period is characterized by the formation of capillary-porous colloidal body; in cement-concrete compositions of this period is determined by the development of the processes of setting and which is characterized by low rate of interaction of the binder with water (J. D. Birchall, A. J. Howard, Double D. D. Some general considerations of membrane/osmosis model for portland cement hydration // Cement and Concrete Research, 1980, V. 10, p.145-155). The duration of induction period from the start of mixing of the concrete mix before it is completed�message is usually from a half to two hours and it has the important practical significance because it allows the formation of products based on cement-concrete systems (Midgley H. G., Illstong M. Some comments on the micro structure of hardened cement pastes.// Cement and Concrete Research, 1983, v.13, No. 2, p.197-206).

Next after the induction period is the stage of acceleration of hydrate formation and the early stage of deceleration (the transition period) (S. I. Kontorovich and others Intergrowth of particles in supersaturated solutions during chemical modification of their surface // Hydration and hardening binding agents, Lviv, 1981, p. 60). At this stage forms a colloidal-crystal structure - quasi-solid capillary-porous body; this stage is characterized by the aging of the cement gel and development of crystallization hardening. Here mass formation of hydrates leads to the decrease of the reaction rate, which is limited by the diffusion of water molecules to the surface of the binder (Collepardi M. Low-slump-loss superhlasticized concrete. // Transp. Res. Rec, 1979, No. 720, p.7-12).

Final stage of hardening mechanism is the formation of capillary-porous structures - solid capillary-porous body whose status is determined by the laws of solid-phase interactions between the particles/aggregates of particles and intense growth of safety (L. B. Svatovo, etc. Dielectric measurements in the early stages of hardening of monomineral binders. // Russian journal of applied chemistry, 1973, vol. 46, No. 6, pp. 1219-1223, and takeem.M. Sychev. The role of electronic effects in the hardening of cements. // Cement, 1984, No. 7, pp. 10-13).

Data analysis of experimental measurements made on the basis of the same sample of concrete/mortar in the time interval 100-125 min, the corresponding end of the induction period of hardening of the concrete mix, confirms that the specified time interval is the most informative for the construction of kinetic curves "Strength - Time" and "Electric resistance - Time" on which to build the desired correlation between the electrical resistance of concrete mixture in two hours after pouring the concrete mix into the container sensor and the strength of concrete of a given class on the 28th day.

The method is as follows.

Research methodology structural hardening Portland cement concretes (hereinafter - the concretes) full range of classes from V7. 5 to B80 on the ability to predict their actual ultimate strength according to the claimed invention is the same, so the description of the implementation of the method is demonstrated on two examples - the choice of a concrete class B40 and class B15, as the most common in construction.

To study the solidification of heavy concrete class B40 were taken Portland cement M 500 TO Maltsov, Novorossiysk and Volsk cement plants, and for �of etona class B15 - Portland cement M 400 TO the Voskresensk cement plant and other components - sand, gravel, chemical additives and water, which was prepared concrete mix class B40 on the cements of different plants (table 1) and the composition of concrete mixtures at the Voskresensk cement plant (table 2). In tables 3 and 4 show respectively the performance of the concrete strength classes B40 and B15 in the interval of nine hours - 28 days".

The method allows for the prediction (estimation) final actual strength concretes (S) at the age of 28 days based on the results of measurements of electrical resistivity (ℜ) WES in the early stage of curing of concrete in the induction period of hydrate formation (in the period from a half to two hours).

The prediction of strength is based on using the correlation S(τ)=ψ1(ℜ) (here S(τ) are the predicted values of strength in the desired age: τ=2, 3, 7, 14 and 28 days, ℜ* - base value WES).

Monitoring (assessment and development status of cement-concrete mixtures in the process of hardening a non-destructive method according to GOST R 53231-2008 in real time was used a device measuring parameters of cement-concrete mixtures ConTest-8, certified and listed in the State registry of measuring instruments, Registration No. 45346-10.

Measuring parameters (meter�traveler system) consists of multi-channel measuring unit, personal computer and container sensors to measure the electrical resistance of the material being tested.

In the personal computer of a measuring system incorporated a set of managers and manufacturing programme "Monitor". For the normal functioning of the meter was used, the operating system is Windows XP and the update tool NetFrame software update, which is the mandatory support of the program "Monitor". And if necessary the required elements of the software can be downloaded from Microsoft UpdateCenter (http://windowsupdate.microsoft.com).

The principle of operation of the meter is in continuous conductivity measurement method of the electrical resistance of the sample placed in the container sensor.

To obtain the dependence between the electrical resistance of the samples and their mechanical strength in accordance with GOST standard 22690-88 simultaneously with the filling of the container the sensor of the studied cement-concrete mixture control samples are manufactured according to GOST 10180-90. Further, the process of hardening of the samples and control samples is in the same terms.

In the recommended time standards are measured strength of the control specimens, and the measurement results are used to determine the calibration relationship between the electrical resistance�the pressure and strength of concrete, used for monitoring and forecasting the strength of the studied concrete.

In practice, the full range of concrete classes from v3. 5 to B80 correlation S(τ)=ψ1(ℜ) is defined on the results of the calibration tests specified compositions are usually concrete the basic range of classes V7,5-B40 design strength (normalized concrete strength at age of 28 days according to GOST 27006-86) taken from a statistically reliable number of batches of concrete, which are the most popular for jbk enterprises - manufacturers of concrete mixes using cement of the same brand.

To build correlation "Strength - WES" based on the same sample of concrete was experimentally establish the variation of the strength S and the electrical resistance ℜ, i.e. get the basic of kinetic curves S*=ƒ(τ) and ℜ*=φ(τ). The curve in the same moments of time τ (τ1, τ2...τndetermine the values of S and ℜ and build the required calibration curve S*(τ)=ψ (ℜ*).

For each concrete test batch to determine the value of ℜ* by sequentially measuring the resistance in a fixed moment of time τ from the start of curing of concrete in the induction period and after completion of the processes of setting - even at the stage of crystallizationsupernova, for example, at the age of 20 hours after the beginning of the hardening process of concrete hardening and at the same fixed time points in parallel for each test batch of concrete in the laboratory of the factory standard method to determine the strength of concrete S11),...Sn(τn)in a timely τ1...τn.

The obtained calibration compositions of concrete mixes based on cement from different manufacturers allow us to obtain statistical sets of values of electrical resistance ℜ* and accordingly the values of concrete strength that gives you the ability to graphically display coordinates "Strength (MPa) Time (h)" - "electrical resistivity (Ω·m)* - (h)". Next, the base rate ℜ* correlated with corresponding values of concrete strength S(τ) and receive correlation S(τ)=φ (ℜ*) in the form of a quadratic equation.

On the established correlation forecasting the strength measurement is carried out (ℜ) WES in the sample test batches of concrete at the age of 20 hours on the basis of cement of the same brand of cement from other suppliers with subsequent extrapolation of the obtained

Fig. 1-5 presents test data in the form of diagrams, curves which represent correlations between the electrical resistance of concrete mixture �through two hours after pouring into a container sensor and the strength of the concrete class B40 on the 28th day cements from different manufacturers, including concrete class B15.

Fig. 1 shows the correlation for the concrete mix at the Maltsov cement, Fig. 2 and 3, correlations for concrete mixes respectively at Novorossiysk and Volsky cements, Fig. 4 - consolidated graphic displays correlations for concrete class B40 in Fig. 5 - correlation for concrete class B15 resurrection on the cement.

During the execution of a series of experiments was a close correlation between the values of electrical resistance of concrete mixture in two hours after loading of the container sensor and the strength of the concrete class B40 28 days for example Maltsov cement (Fig. 1) and concrete strength class B15 on the 28th day example of Voskresensk cement cement (Fig. 5).

To describe the experimental data (increasing and decreasing in absolute value) was chosen polynomial trend line (polynomial of second degree). Close to unity, the value of reliability of approximation (>or = 0.97) indicates a good match curve with the experimental data; measuring the electrical resistance of concrete mixture in two hours after pouring the concrete mix into the container sensor, shown on the schedule or formula it is possible to estimate the ultimate strength of concrete.

This process can be simplified, using methods� standard deviations (C. O.). The method is based on determining a standard deviation (measure of dispersion in statistics, STDev) in technical analysis (V. P. Borovikov. Statistica-Statistical analysis and data processing in the Windows environment", Publishing house "Filin", St. Petersburg, 1997, 608 S.).

In particular, having a set of statistical values of electrical resistance of concrete mixture, on the one hand, and the set of values of ultimate concrete strength, on the other hand, with this analysis it is possible to establish communication between groups of measurements and to estimate the change of one parameter in a certain range depending on the change of another parameter in the appropriate range (for example concrete class B40 at the Maltsov cement (table 5) or for concrete class B15 on the resurrection cement (table 6).

The received data is easily used for practical evaluation of the predicted concrete strength by the values of electrical resistance as follows. When the gross valuation (Av+2STDev) for concrete class B40 in the range of resistivity of 50 Ω·m - 69 Ohm·m values of concrete strength will be in the range of 49.5 MPa to 56 MPa, and for concrete class B15 in the range of resistances 65-88 Ohm·m projected strength will be in the range of 20-28 MPa.

Thus, by measuring the electrical resistance of concrete mixture in two hours after pouring it into contact�enemy sensor, you can estimate the value of concrete strength at 28 days. A more accurate value of strength for a concrete class B40 can be calculated by the formula in Fig. 1, and for concrete class B15 - according to the formula in Fig. 5. The error of determination of concrete strength in this case (with standard deviation) does not exceed 3.5%.

It should be borne in mind that the final strength of concrete is determined according to the standard 28 days with a coefficient of variation (i.e., the error) equal to 13%. This means that based on the above the error is often inevitable overrun of cement, whereas the implementation of the present invention reduces the error by almost four times, thereby saving both material resources and energy consumption in concrete technology.

A method of predicting final actual concrete strength, including conductometric measurement of electrical resistivity and temperature during the curing of the samples of concrete mixes in real time with the subsequent evaluation of the actual mechanical compressive strength of concrete samples of a given class, Otley�audica, produce a parallel measurement of the specific electrical resistances of the samples of concrete mixtures calibration and calculation of the nominal compounds and establish the correlation between electrical resistivity and the actual mechanical strength of concrete of a given class in its design age and the results of analysis of changes in electrical resistivity of the specimen concrete mix specified composition of a given class of concrete in a time interval equal to 100-125 minutes after pouring in the sensor container type specimens of both concrete mixes, provide control of early hardening of the samples of the concrete mix specified concrete grade and end-actual mechanical strength of concrete in compression.



 

Same patents:

FIELD: construction.

SUBSTANCE: method comprises the preliminary moistening of concrete sample and its subsequent heating, in which the thermal emission is carried out in case of discharging of 700 mm Hg and temperature of 80-300°C.

EFFECT: increase of the efficiency and acceleration of analysis.

1 dwg

FIELD: construction.

SUBSTANCE: study the interaction of fibreglass with cement stone within the specified time. Previously, the fibreglass is glued on the plastic plate, put into the mould to prepare cement samples and filled with cement slurry. Plastic plate with the glued fibreglass is put in such a way that the fibreglass is in contact with the cement slurry. After solidification the cement specimens are removed from the mould and the fibre is separated from the plate. Then, the fibre is investigated by means of X-ray spectrum analysis and electron microscopy. Method allows to determine the element composition, structure of interaction products of fibre with cement stone. Besides, the resistance of fibreglass compared with the diameter of fibreglass after test with the diameter of raw fibre is evaluated.

EFFECT: invention makes it possible to compare the use of fibreglasses of various compositions as reinforcing materials.

7 dwg

FIELD: testing technology.

SUBSTANCE: invention relates to construction, in particular to determining the parameters of deformation of concrete under conditions of cyclic loading to a level not exceeding the tensile strength of concrete to compression Rb and extension Rbt. Essence: securing a test concrete sample in the form of a prism in the jaws of the test stand is carried out using a centring device which provides a central application of load during loading. The force and deformation of the prism in time is registered by using the dynamometer and the strain-gauge station. The multiple static or dynamic loading is performed by rotating and short-term changing the diameter of the axis in the place of junction of the lever and the compensating element.

EFFECT: simplification of the test method, expanding the functional capabilities of the experimental determination of the static-dynamic characteristics of concrete under conditions of cyclic loading, which consists in alternating application of static and dynamic loads on the sample.

4 dwg

FIELD: construction.

SUBSTANCE: method is realised by fixation of an experimental concrete sample in the form of a prism in clamps of a test bench using an alignment device, providing for central application of stretching load in process of loading, and registration of a force and deformations of the sample in time using a dynamometer and a strain gauge station during loading executed via a lever system in two stages: at the first stage - stepped static loading of the sample to the specified level by means of laying of piece weights onto a load platform, at the second one - instant or stepped dynamic additional loading or unloading by means of short-term variation of the axis diameter in the point of force transfer from the lever to the compensating element, setting, if necessary, the value of movements in the elastic element.

EFFECT: simplified methodology and increased validity and reliability of test results.

5 dwg, 2 ex

FIELD: test equipment.

SUBSTANCE: method relates to test methods of porous water-saturated bodies. It provides for production of a series of concrete specimens, saturation of specimens with water, measurement of specimens, determination of their initial volume, their frosting/defrosting to specified temperatures and recording of deformation. In addition, long-term strength limit of each specimen is determined by a non-destructive method under tension conditions. After defrosting, relative residual deformation of specimens is determined and energy dissipated in unit volume of each specimen is determined during its frosting/defrosting. Then, they are loaded under conditions of uniaxial compression to an extreme load meeting short-term strength limit; energy dissipated in unit volume of the specimen is determined during its compression to an extreme load, and as per the obtained results, grade is calculated as per freeze resistance of each specimen. Grade of concrete as to freeze resistance is determined as an arithmetic mean for grades of specimens.

EFFECT: increasing flexibility, reducing labour intensity and enlarging the number of hardware.

1 tbl

FIELD: construction.

SUBSTANCE: previously prepared samples with various quantity of a filler in a highly dispersed condition for a dry construction mix are placed into a hollow part of metal washers, placed on a metal plate, are compacted by any available method under permanent load of up to 5 MPa per 1 cm2 of sample surface for 10-15 seconds, then marks are applied on the surface of each sample in the form of drops of a solution of various concentration, wetting angles of samples are measured θ, a curve of dependence is built cosθ-1=f(1/σl), where σl - surface tension of the liquid, they determine the angle of inclination of this functional dependence a for each sample of different composition, the curve of dependence a is built on quantity of mix components, and by the point of break of the curve of dependence they define the optimal content of a modifier in the tested object.

EFFECT: reduced number of tests and higher accuracy of mixture composition selection.

2 cl, 2 dwg, 1 tbl

FIELD: test equipment.

SUBSTANCE: at the first stage they determine process mode of manufacturing of ceramic items providing for required operability reserve. Using the produced operability reserve and knowing the suggested time, during which ceramic items must preserve strength parameters, they assess the permissible rated speed of produced reserves consumption. At the second stage, modelling conditions of real operation by means of reproduction of accelerated cyclic variations of temperature with simultaneous impact of possible mechanical factors, they determine actual speed of consumption of the same reserves. Received results of rated permissible speed and actual speed produced for imitation of operation conditions are compared, and results are produced, making it possible to judge on ceramic items.

EFFECT: possibility to determine durability of ceramic items with regard to certain conditions of use.

3 dwg

FIELD: measurement equipment.

SUBSTANCE: invention relates to the field of tests of cement plastering compounds for tensile strength under static loading. Substance: the value of the limit tensile strength is defined by testing steel beams with applied plastering compound according to the scheme of the double-point bend with smooth loading by small steps and fixation of the loading step corresponding to the moment of cracking, and the value of the limit tensile strength is calculated using the formula.

EFFECT: simplified technology for testing, exclusion of the necessity to apply strain metering facilities, higher accuracy of detection of limit tensile strength and completion of tests on plaster layers with specifically small thickness from several mm to 2-3 cm.

1 tbl, 1 dwg

FIELD: construction.

SUBSTANCE: method involves measurement of hardening concrete temperature at given time moments and calculation of concrete strength over three days for hardening in standard conditions by the formula: where R, % is concrete strength gained in time τ, days, Kt is temperature factor depending on concrete hardening temperature and three-day strength.

EFFECT: reduced labour consumption of monitoring.

1 tbl, 2 dwg

FIELD: chemistry.

SUBSTANCE: apparatus has at least two sealed chambers with a U-shaped pipe filled with water for releasing excess pressure in the chamber, inlet and outlet gas-distributing manifolds, filters for cleaning the gas-air medium collected from the chambers and the inside of each chamber is fitted with a ventilator and a bath with a saturated salt solution for creating and maintaining given relative air humidity inside the chamber, connected to the sealed chambers through the inlet gas-distributing manifold and, installed on pipes, electromagnetic valves, a carbon dioxide gas source, an automatic gas analyser with a gas flow activator, a gas distribution switch for alternately collecting samples from the chambers and transferring the samples to the gas analyser through the gas flow activator; the gas analyser is also connected to a computer for automatic monitoring of gas concentration in the sealed chambers and feeding gas into the chambers through the electromagnetic valves.

EFFECT: high information value and faster determination.

1 dwg

FIELD: engines and pumps.

SUBSTANCE: control device for an internal combustion engine includes the following: a solid particle sensor installed in an exhaust pipe of an internal combustion engine, a filter for catching particles, which can catch solid particles contained in exhaust gas and is located in the exhaust pipe at the point upstream relative to the solid particle sensor; an electronic control unit that can detect the amount of particles in the exhaust gas through the exhaust pipe in response to an output signal of the solid particle sensor; an electronic control unit having a possibility of supplying particle capture voltage between electrodes of the solid particle sensor during the first period so that a layer of particles can be formed on surfaces of electrodes of the solid particle sensor; and an electronic control unit having a possibility of stopping particle capture voltage supply during the second period so that the layer of particles can be maintained, and an electronic control unit that can perform control by detection of a failure in order to determine whether there is a failure of the filter for particle catching or not. The first period represents a period between completion of control by detection of the failure and the moment when the output signal of the solid particle sensor achieves a reference output signal. The second period represents a period between the moment when the output signal of the solid particle sensor achieves the reference output signal.

EFFECT: improved serviceability of a control unit and high measurement accuracy of the amount of solid particles.

9 cl, 7 dwg

FIELD: medicine.

SUBSTANCE: analysis uses a bipolar method for electrical impedancemetry to determine a module of the electrical impedance |Z| measured at a frequency of 20,000 Hz and low-intensity AC, a solution of monoclonal antibodies, analysed and reference samples. The concentration is calculated by solving a mathematical equation of relations of the analysed and known substance concentrations to the modules of the electrical impedance measured in a test well and a reference sample.

EFFECT: invention enables performing the method to avoid chemical agents and some laboratory equipment in addition to the monoclonal antibodies, and reducing the analysis time.

3 ex

FIELD: instrumentation.

SUBSTANCE: invention relates to area of determination of the electro-physical parameters of the powder materials, and to area of determination of the parameter values characterizing physical and chemical properties of materials according to electrical resistance. Contact device to determine the electric resistance of the powder material upon its compression contains the measuring cell with isolating bush to locate in it the studied material sample, movable and fixed cylindrical electrodes for the sample compression and registration of its resistance change, they are made with lead-in part for locating in the bush; assemblies for creation and measuring of the movable electrode movement. The device novelty is that assemblies for creation and measuring of the movable electrode movement are separated by design. At that the sensitive element of the measuring assembly is kinematically connected with the movement making assembly. The lead-in part of each electrode is made stepped. Step looking to the specimen has lesser diameter and is made with unloading groove on the outside surface, and step with greater diameter is made to interface with the insulating bush. At that bush length L, lead-in part length l1 of the electrodes, and length l2 of the interfaced step of the electrodes in the initial state are selected from the definite geometrical conditions. To ensure possibility of measurements of the powder material specimen being in the inert environments the measuring cell is installed in the tight pipe. To ensure operation characteristics of the contact device linked with possibility of visualization of the specimen and process of its sealing the tight pipe and insulation bush are made transparent.

EFFECT: increased accuracy and expansion pf density measurements range, and hence increased accuracy of electric resistance determination for the studied powder material.

3 cl, 4 dwg

FIELD: chemistry.

SUBSTANCE: detector consists of cylindrical dielectric substrate, layer of electroconductive paint-and-varnish material with dispersed powder-like graphite filler, applied on dielectric substrate, electric contacts and electric wires for connecting direct current source to layer of electroconductive paint-and-varnish coating.

EFFECT: provision of possibility to reduce time for detection of uranium hexafluoride or hydrogen fluoride.

8 cl, 1 dwg, 6 tbl

FIELD: medicine.

SUBSTANCE: method for non-invasive control of a blood metabolite level involving using a sensor array to measure electromagnetic impedances in the patient's epidermic layer and in one of the layers including the patient's skin layer or subcutaneous layer more than once, until an impedance difference exceeds a threshold; calculating the impedance reflecting the above difference with the use of an analogous circuit and an individual adjustment factor specific for the patient's physiological characteristics; and measuring the patient's blood metabolite level on the basis of the impedance and a measurement algorithm of blood metabolite levels, which provides comparing the measured blood metabolite level to the respective patient's electromagnetic impedance. What is also presented is a system controlling a level of at least one of the substances: glucose, electrolyte or a target substance.

EFFECT: invention enables avoiding excessive experiments to adapt it easily for controlling the patient's blood metabolite level.

17 cl, 14 dwg

FIELD: electricity.

SUBSTANCE: system comprises an assembly of capacitance-type primary converters to measure electric capacity (dielectric capacitivity) and electric resistance (electrical conductivity) and temperature, which is placed at mobile equipment inside a settling tank, an assembly of secondary converters coupled to the primary ones and supplying the primary converters with action signals of the preset frequency and amplitude and the instantaneous response values of voltage and current at the primary converters for further processing, a programmable device or an automated workspace for control coupled to the secondary converters through a wired or wireless communications line with functions of data collection, processing and storage, including control over changes in the measured values of dielectric capacitivity and electrical conductivity with time or in regard to a structure of the settling tank, as well as issuing of the final forecast for a level or properties of sediment or sludge.

EFFECT: improving efficiency of automated control for waste water settling tanks.

12 cl, 1 dwg

FIELD: measurement equipment.

SUBSTANCE: invention may be used in systems of water-chemical regime control for thermal, nuclear and industrial power engineering. The method to determine concentration of components in a mixture of highly diluted strong electrolytes includes simultaneous measurement of specific electric conductivity and temperature of analysed solution under different temperatures in quantity equal to quantity of components of the solution, solving a system of equations of electric conductivity in the quantity equal to the number of measurements, each of which has a certain type, with determination of specific electric conductivity values when solving equations at the temperature of 18°C for each of the mixture components and find the corresponding concentration by available (reference) data.

EFFECT: invention simplifies the process due to direct determination of concentration of each component within the composition of the solution.

1 ex,1 dwg

FIELD: measurement equipment.

SUBSTANCE: in the method to determine water saturation of core and other forms of combined water in the core material includes preparation of a sample from core, extraction and drying of the sample, modelling of bed conditions in the core sample, filtration of mineralised water via the core sample and serial measurement of intermediate values of current passing through the sample as AC voltage is applied to it in process of filtration, building of dependence of the electric signal value on the water saturation of the core sample. Additionally, in accordance with the invention, prior to measurements the core is insulated with a thin dielectric shell and placed between electrodes of the capacitance measurement cell, and current values passing via the sample at different values of water saturation (from 0 to 100%), is determined by the method of contactless high-frequency conductivity measurement, for instance, by the method of non-linear unbalanced bridge, supplied with the high-frequency voltage with frequency of 2-10 MHz, using the produced dependence of values of the electric signal on water saturation of the core sample, three areas are identified with different values of rate of rise with growth of water saturation, and borders of energetically different categories of combined water in the core, including the residual water saturation, are determined as points of bending between specified areas with different values of signal slope.

EFFECT: higher accuracy of measurements and simplified process of determination of residual water saturation of core with simultaneous expansion of area of application of the developed method, in particular, other forms of combined water in core material.

2 cl, 5 dwg

FIELD: measurement equipment.

SUBSTANCE: result is achieved due to the possibility of determination of dependence of specific electrical conductivity of ductile substance on pressure. The device includes a dielectric tube, into one end of which there inserted is the first metal sleeve with inner thread, with that, a screw is screwed into it, and in its second end there inserted is the second metal sleeve with a pressure sensor installed on it, which is connected by means of a cable to a pressure recorder. Electrodes are the first and the second metal sleeves connected through current conductors to a resistance recorder. Dielectric tube is sealed.

EFFECT: possibility of determining dependence of specific electric conductivity of ductile substance.

3 cl, 1 dwg

FIELD: measurement equipment.

SUBSTANCE: according to the invention, in order to determine hydrogen content in products made from titanium in layers as to depth of a specimen the value of eddy current is determined at different frequencies; with that, at each frequency there determined is maximum value of eddy current depending on angular position of a sensor; resistances R1 and R2 are measured on frequencies corresponding to difference of depths a1 and a2; electrical conductivity is calculated for the specified depth ax=a2-a1; then, as per calibration reference dependence of electrical conductivity on concentration of hydrogen in titanium there determined is the unknown hydrogen content in a layer as to depth of a titanium product (specimen).

EFFECT: invention provides the possibility of determining hydrogen content in layers of titanium saturated with hydrogen, which are located at different depth, and improves accuracy of determination of hydrogen content.

3 dwg, 3 tbl

FIELD: servicing steel underground pipe lines; diagnosis of corrosion on pipe lines.

SUBSTANCE: pipe line under test is divided into sections and pit is made at boundaries; then electrical resistance is measured in section and at edge zones of these sections (in pits) by four-electrode scheme. Measured at edge zones are also thickness of pipe wall and its outer diameter. Specific resistance of pipe metal is calculated by these measurements. Electrical resistance of sections is calculated on basis of specific resistance and measured and specified magnitude are compared. Deviation of measured magnitude from specified ones is indicative of corrosion damage on these sections. Current and potential electrodes are located at distance no less than two diameters of pipe for enhancing measurement accuracy.

EFFECT: enhanced accuracy of measurement.

2 cl

Up!