Method of concrete strength growth monitoring during heat treatment
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:
EFFECT: reduced labour consumption of monitoring.
1 tbl, 2 dwg
The invention relates to the construction and can be used when carrying out heat treatment of concrete structures.
The known method of monitoring the increase of concrete strength by heat treatment, comprising determining the temperature of curing of concrete at specific points in time and determining the time of achievement of concrete 25%strength in normal conditions used in the calculations of strength of concrete (copyright certificate №1734013 A1, MCP G01N 33/38, 15.05.92)
The disadvantage of the method is based on the assumption that 100% of the strength of concrete under normal conditions is achieved in 28 days, this strength is vintage, although many of the concrete further hardening, which is obtained by this method the strength is not sufficiently accurate. In addition, the proposed method is time-consuming, because the timing of achievement of concrete 25%strength involves the implementation of measurement strength (test samples) throughout the period of hardening.
The invention solves the problem of reducing the complexity of control over the strength of concrete by determining the value of a three-day concrete strength under normal conditions and use in the calculation of the correction factor that takes into account the increase in the time of curing when the deviation from normal is s conditions temperature curing of concrete.
To obtain the desired technical effect in the known method of monitoring the increase of concrete strength by heat treatment, comprising determining the temperature of curing of concrete at specific points in time and strength, it is proposed to define a three-day concrete strength under normal conditions, and concrete strength to be calculated by the formula:
On the above chart shows:
figure 1 - dependence dialed strength of concrete of different grades depending on the time when the temperature setting 20°C; R, % - typed concrete strength at time τ, d;
figure 2 - dependence of the temperature coefficient from a three-day strength R3concrete and temperature curing; Kt- temperature coefficient, t,°C - temperature hardening.
The method is as follows.
Make samples of concrete 10×10×10 cm Place the samples in the chamber normal storage and incubated for 28 days.
Sample test for compressive strength after 3 days and after 28 days. Then define a three-day concrete strength R3as p is ocent of nominal strength R 28adopted by over 100%.
Studies have shown that the dependence of curing the concrete stamps, a three-day strength of which R3is in the range of 30÷60% of nominal strength R28concrete, at a temperature of 80°C are almost equal (see figure 1, the deviation of the set of specified strength is less than 5%). Thus, the time a set of concrete specified strength at a temperature of 80°C can be based, without taking into account three-day strength characterizing mark of concrete. The time during which the concrete used brand reaches the required strength shall be determined by multiplication of the time achieve this concrete strength at a temperature of 80°C by a factor of Ktdependent three-day concrete strength and temperature of the curing concrete. For each used in the production of concrete brand pre-experimentally determine the coefficients Ktat different temperatures of concrete hardening, for example, with an interval of 10°C, as shown in the table:
According to the experimental data, construct graphs of the temperature coefficient of the Ktfrom a three-day strength R3concrete and temperature of curing concrete t°C. Intermediate values are determined by interpolation.
In the process of heat treatment of concrete structures or products in the production of first define the concrete temperature t°C at a given point in time. Then on a three-day concrete strength R3and measured the temperature of the concrete is determined by pre-established the dependency of the temperature coefficient of Ktdetermining the increase in time of curing ecosmarte concrete relative to the time set of the same strength at temperature, equal to 80°C. the Strength of concrete, dialed within a certain time, determined by the formula:
where R, % - strength concrete, collected at time τ;
Kt- temperature coefficient, which is determined depending on the temperature of the curing concrete and three-day concrete strength under normal conditions.
A specific example of the method.
For example, it is necessary to determine the strength, which is gaining concrete grade 200 Portland cement grade 300 for 45 hours at 50°C.
Make samples of concrete 10×10×10 cm Place the samples in the chamber normal storage and incubated for 28 days. Test specimens for compressive strength after 3 days and after 28 days define a three-day concrete strength R3=40%.
From the above table, or the graphs in figure 2 determine the temperature coefficient of Kt=2,360.
According to the formula determine the strength of this brand of concrete when the temperature setting of 50°C, which he scored for 45 h:
K=100-82,09*e^(-0,961*45/24*1/2,36)=61.7 per cent.
The proposed calculation of the strength of concrete is much easier than described in the nearest analogue, in addition, it has been experimentally confirmed by the increase in the accuracy of determination of concrete strength by approximately 10%, compared with the nearest equivalent.
The control method for Nuristani the feet of concrete strength by heat treatment,
includes determining the temperature of curing concrete, specific points in time, and strength, characterized in that the determined three-day strength of concrete during hardening under normal conditions, and the strength of concrete is determined by the formula
where R, % - strength concrete, accumulated within time τ, d;
Kt- temperature coefficient, which is determined depending on the temperature of the curing concrete and three-day strength.
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.
SUBSTANCE: previously they make at least two samples with different water-cement ratios, thermal cycling and cyclic compression of the sample with the least water-cement ratio are alternated until proportion is disturbed between relative residual deformation and number of cycles, the ratio is calculated between relative reduction of threshold load and relative residual deformation, the concrete grade of frost resistance is determined, as well as relative residual deformation εm, corresponding to reduction of the strength limit specified by the standard for the frost resistance grade of the investigated concrete, they alternate thermal cycling and cyclic compression of other samples with higher water-cement ratios until residual deformation is achieved εm, the number of cycles required for this purpose is accepted as the grade of concrete frost resistance with higher water-cement ratio, using the produced results, they calculate parameters of the function that approximates experimental results.
EFFECT: expanded arsenal of technical facilities for detection of concrete frost resistance dependence on water-cement ratio.
SUBSTANCE: in the method including drying of a sample to permanent mass, hydraulic insulation of its side surfaces and water saturation, nonwetting of the upper end surface of the sample is provided, and a light-reflecting water impermeable coating is applied on it, and continuous even water saturation is carried out via the bottom end surface of the sample, at the same time the sample is installed onto fixed supports inside a reservoir for water saturation, the reservoir is filled with water, and even contact is provided between the lower end surface of the sample with water during the entire cycle of measurements, then with the help of laser radiation a series of holographic interferograms is registered on a non-wetted surface of the sample in process of water saturation, at the same time position, speed and acceleration of moisture movement front are determined by comparison of changes in the field of movements of the registered surface, produced according to interferograms, with the rated field of movements of a geometrically similar sample.
EFFECT: improved information value and reliability of detection.
2 cl, 1 dwg
SUBSTANCE: method is realised by fixation of an experimental concrete sample in the form of a prism between bearing plates of a test bench using a centring device, providing for central application of a compressing load in process of loading, and registration of a force and deformation of a prism in time using a dynamometer and a strain station with loading, realised through a lever system in two stages: at the first stage - stepped static loading of a sample to the required level in different shares of the crack formation load by means of laying of unit weights onto a loading platform, at the second stage - instantaneous or stepped dynamic additional loading with a weight dropping during reduction of current force in an electromagnet, the axis of the centre of gravity of which matches with the axis of the loading platform.
EFFECT: increased reliability of tests.
SUBSTANCE: method involves dipping and holding samples of the test materials at room temperature into a weakly aggressive medium - mixture of organic acids: 0.9-1.1% acetic acid, 0.9-1.1% citric acid, 0.09-0.12% oxalic acid, said acids being in ratio of 1.8:2.7:0.8-2.1:3.1:1.2. After exposure, the samples are removed and dried to constant weight and their strength characteristics are then determined.
EFFECT: high efficiency and reliability of tests.
SUBSTANCE: method includes soaking concrete, drilling concrete, detection of power spend for drilling, measurement of value and speed of drilling tool displacement with production of data in the form of curves of power, displacement, speed of the drilling tool, characterising structure and layer strength of concrete with production of digital data on each curve, besides, prior to performance of tests on this investigated section of a concrete item selected for detection of structure and strength of concrete, preliminary preparation of the concrete item surface is carried out, for this purpose the investigated section is polished, and its surface strength is determined in dry condition, then this section of the concrete item is soaked, and surface strength of concrete is identified with account of its moisture, then a drilling plant is installed on the investigated section for drilling of concrete, and by means of drilling, the layer structure and layer strength of concrete in moist condition are identified, besides, as a result of drilling, additionally a cylindrical reference concrete sample is produced, which is used for further tests during determination of strength of the reference concrete sample for compression or axial tension, at the same time readings are compared with readings produced by other previous methods, and the reference concrete sample is previously dried. Also a device of similar purpose is provided.
EFFECT: increased accuracy and reliability of analysis and monitoring.
8 cl, 10 dwg
FIELD: machine building.
SUBSTANCE: invention relates to structural element 11 from electrically insulating material with structure made up of conductors 14a, 14b, 14c to reveal mechanical damages, say, fractures. Said structure varies its electrical properties in continuing fracture formation (arrow 20) to allow timely replacement of structural element 11. In compliance with this invention, said electrical conductor consists of particles with metal surface that stay in contact. This allows making the electric conductor that reacts to mechanical damages to increase sensitivity of aforesaid structure 14a, 14b, 14c. If said metal surface is formed solely by shell of particles and particles consist of the material of structural element 11, then it is possible to develop a conductor with matching characteristics of thermal expansion for thermally heavily-loaded structural parts, in particular, plates of heat protection shield.
EFFECT: higher sensitivity in detection of damages.
8 cl, 6 dwg
SUBSTANCE: method includes monitoring quality of finished mix, initial components of the mix, their dosing, mixing, maintenance of the specified temperature mode and registration of mix temperature at the outlet of the mixer, besides, at all stages of the technological process the spectral density of acoustic noise capacity is registered, and the mixture readiness and necessity to disconnect the mixer's drive are decided by change in density of distribution of the spectral density of capacity radiated by fractions of filler during mixing depending on extent of mixture homogeneity.
EFFECT: higher informative value and reliability of monitoring.
3 cl, 1 ex, 2 dwg
FIELD: technological processes.
SUBSTANCE: method can be used in field of road-building materials. When estimating cohesion of filling agent with mortar part of asphaltic concrete fixed is stamp-standard from three rigidly connected similar elements with lower part from filler in mortar part of examined asphaltic concrete at specified depth of metal reservoir, connected with bed, by fastening stamp-standard in rod system, moving it with respect to surface of mortar part of examined asphaltic concrete by means of thread connection, connected with rod system. After that, metal reservoir is rotated at 180° with respect to bed. Then, stretching effort is created in contact zone of each element of stamp-standard by application to each of three similar elements of stamp-standard of static rupture loading, said loading is recorded at the moment of breaking off of each of three similar element of stamp-standard, located at angle 120° with respect to each other, from mortar part of examined material, and value of tension in contact zone of each of three similar elements of stamp-standard by value of ratio of loading value to size of area of contact zone between filling agent - lower part of each of three similar elements of stamp-standard - and mortar part of asphaltic concrete.
EFFECT: increased accuracy of experimental estimation of cohesion parameter and reduced labour consumption of method realisation with application of great number of stamp-standards.
3 dwg, 1 tbl
SUBSTANCE: method to detect frost resistance of a coarse filler in concretes by means of saturation of investigated concrete with water and their cyclic freezing-thawing is characterised by the fact that prior to testing a surface layer is removed from the samples, thus baring grains of a coarse filler. Thickness of the removed layer makes at least a half of a diameter of coarse filler grains, and hardness of bare filler grains is detected in process of cyclic freezing-thawing.
EFFECT: detection of actual frost resistance of a coarse filler in concretes, with simultaneous detection of kinetics of filler grains destruction and mortar fraction.
1 cl, 2 tbl
FIELD: manufacture of building materials.
SUBSTANCE: object of invention is testing materials for use in designing compositions of artificial building conglomerates and composites as well as in optimizing compositions. Method of invention involves screen fractionation to determine average size of grains of coarse-grain fraction d1 and that of fine-grain fraction d2, ratio of grain sizes d2/d1, and value of dilution of coarse-grain fraction with fine-grain fraction in terms of formula: α = [(d1 + d2)/d1]3. If d2/d1 > 0.155, degree of compaction Y and, if d2/d1 < 0.155, degree of filling Y are found from formula Y = 2 -
EFFECT: reduced volume of laboratory tests and improved qualitative characteristics of calculated and prepared loose mixtures, for which regulation of desired properties of manufactured materials is ensured.
FIELD: manufacture of building materials.
SUBSTANCE: object of invention is testing materials for use in designing compositions of artificial building conglomerates and composites based on organic and inorganic binders. Method of invention involves screen fractionation to determine average size of grains of coarse-grain fraction d1, mm, and fine-grain fraction d2, mm, ratio of grain sizes d2/d1. Degree of compaction Y at d2/d1 > 0.155 and degree of filling Y at d2/d1 < 0.155 are determined from formula Y = 1 - d2/d1.
EFFECT: enabled determining values of degree of compaction and filling of coarse-grain fractions with fine-grain ones without experimental trials associated with preparation of loose mixtures.
FIELD: manufacture of building materials.
SUBSTANCE: object of invention is testing materials for use in designing compositions of artificial building conglomerates and any-nature composites. Method of invention comprises layer-by-layer filling of volume unit with coarse-grain and fine-grain fractions, determining average size of grains of coarse-grain fraction d1 and that of fine-grain fraction d2, d2/d1 ratio, coarse-grain and fine-grain fraction volumes V1 and V2, m3, respectively, consumed per unit mixture volume (1 m3), coarse-grain fraction free volume value Vn1, coarse-grain fraction volume mass γ1, and degree of diluting coarse-grain fraction with fine-grain fraction α calculated by formula: α = γ1/V1. When d2/d1 > 0.155, degree of compaction of coarse-grain fraction with fine-grain fraction Y is calculated using formula: V = [α(V2-1)+1]/Vn1. Invention makes it possible to determine degree of compaction of one-type fractions with other-type fractions taking into account quantitative interrelations between fraction ratios, between fraction ratios and volume of mixture being formed, between volume of mixture and coarse-grain fraction free volume value, between all them and above-indicated dilution value.
EFFECT: enabled regulation of volume mass and preparation of materials with desired volume-mass characteristics.
FIELD: technologies for testing properties of materials.
SUBSTANCE: in method for determining compositions of friable bi-senary systems of expanded type with core dimensions in fractions determined by method of sieve analysis or sedimentation method, fraction volumes are determined for binary systems: V1=1/α 1, m3, V2=V1(α 1-1), m3, α 1=(1+d2/d1)3, m3, for ternary systems V1=1/α 1, m3, V2=V1((α 1-1)/ α 2), m3, V3=V2(α 2-1), m3, α 1=(1+(d2+2· d3)/d1)3, m3, α 2=(1+d3/d2)3, m3, for quaternary systems V1=1/α 1, m3, V2=V1((α 1-1)/ α 2), m3, V3=V2((α 2-1)/ α 3), m3, V4=V3(α 3-1), m3,
α 1=(1+(d2+2· d3+4· d4)/d1)3, m3, α 2=(1+(d3+2· d4)/d2)3, m3, α 3=(1+d4/d3)3, m3, for quinary systems V1=1/α 1, m3, V2=V1((α 1-1)/ α 2), m3, V3=V2((α 2-1)/ α 3), m3, V4=V3((α 3-1)/ α 4), m3, V5=V4(α 4-1), m3, α 1=(1+(d2+2· d3+4· d4+8· d5)/d1)3, m3, α 2=(1+(d3+2· d4+4· d5)/d2)3, m3, α 3=(1+(d4+2· d5)/d3)3, m3, α 4=(1+d5/d4)3, m3,for senary systems V1=1/α 1, m3, V2=V1((α 1-1)/ α 2), m3, V3=V2((α 2-1)/ α 3), m3, V4=V3((α 3-1)/ α 4) ,m3, V5=V4((α 4-1)/α 5), m3, V6=V5(α 5-1), m3, α 1=(1+(d2+2· d3+4· d4+8· d5+16· d6)/d1)3, m3,
α 2=(1+(d3+2· d4+4· d5+8· d6)/d2)3, m3, α 2=(1+(d4+2· d5+4· d6)/d3)3, m3, α 3=(1+(d5+2· d6)/d4)3 ,m3, α 4=(1+d6/d5)3, m3, where V1,V2,V3,…,V6 - fractions volumes with core sizes d1,d2,d3,…,d6,m3; α 1, α 2, α 3, ... , α 5 - volumetric coefficients of separation of cores with d1 dimension by all other cores, dimension d2 by all other cores, etc.
EFFECT: higher efficiency.
FIELD: technologies for testing properties of materials.
SUBSTANCE: in method for determining compositions of friable systems of condensed-expanded type in fractions with core sizes D1>D2>D3>D4>D5 when D2/D1,…,D5/D4 greater than 0.155 volumes of fractions VD1, VD2, VD3, VD4 having core sizes D1, D2, D3, D4 respectively, m3, are determined, as well as core material denseness, average core size, value of emptiness VeD1 of fraction with core size D1, condensation grade coefficients Y1, Y2, Y3, of fraction with core size D1 by fraction with core size D2, mixture of condensed type on basis of fraction (D1+D2) with average sizes of cores Dav.sm2 by fraction with core size D3, mixture of condensed type on basis of fractions (D1+D2+D3) with average core size Dav.sm3 by fraction with core size D4 respectively, fractions with large core sizes are used for receiving mixtures of condensed type, condensed type mixtures volumes Vsm2, Vsm3, Vsm4,are determined on basis of fractions (D1+D2), (D1+D2+D3) and (D1+D2+D3+D4) respectively, m3, emptiness value Vemp2, Vemp3, of condensed type mixtures on basis of fraction (D1+D2) and (D1+D2+D3) respectively, separation of cores in condensed type mixture is performed by fractions with lesser core sizes, separation coefficient α1, α2, α3, value is determined, for mixture cores on basis of fractions (D1+D2) with core sizes D3, mixture cores on basis of fractions (D1+D2+D3) with core sizes D4, mixture cores on basis of fractions (D1+D2+D3+D4) with core sizes D5, respectively, and compositions of friable condensed-expanded type are determined from formulae in following order: composition of condensed type binary mixture on basis of fractions (D1+D2) from formulae m3, m3m3, Y1=1-D2/D1, 1 m3 of said condensed type binary mixture Vem2=VD1+VD2=1m3 for preparation of ternary condensed-expanded type mixture, composition of which is determined from formulae composition of ternary condensed type mixture is determined on basis of fractions (D1+D2+D3) from formulae 1 m3 of said ternary condensed type mixture is used for preparation of quaternary mixture of condensed-expanded type, composition of which is determined from formulae composition of quaternary condensed type mixture is determined on basis of fractions (D1+D2+D3+D4) from formulae Ysm3=1 m3, 1 m3 of quaternary condensed type mixture is used for preparation of quinary condensed-expanded type mixture, composition of which is determined from formulae
EFFECT: higher efficiency.
FIELD: technologies for testing properties of materials.
SUBSTANCE: in method for determining compositions of bi-senary friable filled-separated type systems in fractions with core sizes d1>d2>…>d6 when d2/d1,…,d6/d5 less than 0.155 volumetric mass and denseness of core material is determined as well as emptiness value, empty spaces fill grade coefficient, volumetric separation coefficient, and fraction volumes are determined from formulae for binary systems V1=1 m3/α 1, m3,
V2=V1(У1·Ve1 + α 1-1), m3, Y1=1-d2/d1, α 1=(1+d2/d1)3, Ve1=1-γ 1/ρ 1, for ternary systems V1=1 m3/α 1, m3, V2=V1((Y· Ve1+α 1-1)/α 2), m3, V3=V2(Y· Ve2+α 2-1), m3, y1=1-d2/d1,y2=1-d3/d2, α 1=1-d2/d1, α 2 =(1+(d2 + 2· d3)/d2)3, Ve1=1- γ 1/ρ 1 Ve2=1-γ 2/ρ 2, for quaternary systems V1=1m3/α 1, m3, V2=V1((Y1Ve1+α 1-1)/α 2), m3, V3 =V2((Y1Ve2+α 2-1)/α 3), m3, V4=V3(Y3 Ve3+α 3-1), m3, у1=1-d2/d1, y2=1-d3/d2, y3=1-d3/d3, α 1=(1+(d2+2· d3+4· d4)/d1)3, α 2=(1+(d3+2d4)/d2)3, α 3=(1+d4/d3)3, Ve1=1-γ 1/ρ 1,Ve2=1-γ 2/ρ 2, Ve3=1-γ 3/ρ 3, for quinary systems V1=1m3/α 1, m3, V2=V1((Y1Ve1+α 1,-1)/α 2), m3, V3=V2((Y2Ve2+α 2-1)/ α 3), mз, V4=V3((Y3Ye3+α 3-1)/α 4), m3, V5=V4(V4Ve4+α 4-l), m3, У1=1-d2/d1, y2=1-d3/d2, y3=1-d4/d3, y4=1-d5/d4, α 1=(1+(d2+2· d3+4· d4+8· d5)/d1)3, α 2=(1+(d3+· 2· d4+4· d5)/d2)3, α 3=(1+(d4+2· d5)/d3)3, α 4=(1+d5/d4)3, Ve1=1-γ l/ρ 1, Ve2=1-γ 2/ρ 2, Ve3=1-γ 3/ρ 3, Ve4=1-γ 4/ρ 4, for senary friable systems V1=1 m3/α 1, m3, V2=V1((Y1Ve1+α 1-1)/α 2), m3,V3 =V2((Y2Ye2+α 2-1)/α 3), m3, Y4=Y3((Y3Ye3+α 3-1)/ α 4), m3, V5=V4((Y4Ve4+α 4-1)/α 5), m3, V6=V5(Y5Ve5+α 5-1), m3, Y1=1-d2/d1, Y2=1-d3/d2, Y3=1-d4/d3, Y4=1-d5/d4, Y5=1-d6/d5, α 1=(1+(d2+2· d3+4· d4+8· d5)/d1)3, α 2=(1+(d3+2· d4+4· d5)/d2)3, α 3=(1+(d4+2· d5)/d3)3, α 4=(1+d5/d4)3, α 5=(1+(d6/d5)3, Ve1=1-γ 1/ρ 1, Ve2=1-γ 2/ρ 2, Ve3=1-γ 3/ρ 3, Ve4=1-γ 4/ρ 4, Ve5=1-γ 5/ρ 5, where V1, V2, V3, V4, V5, V6 - volumes of fractions with cores sizes, respectively, d1, d2, d3, d4, d5, d6, m3; Y1, Y2, Y3, Y4, Y5 - coefficients for large core size fractions' empty spaces fill grade with fractions having lesser core sizes, dimensionless quantities; 0<Y<1; α1, α2, α3, α4, α5 - volumetric separation coefficients for fractions with large core sizes by all fractions with lesser core sizes, dimensionless quantities, in binary systems 1<α<8; Ve1, Ve2, Ve3, Ve4, Ve5 - values of fractions emptiness with core sizes, respectively, d1, d2, d3, d4, d5, dimensionless quantities (relation of emptiness' volume to fraction volume), ρ1, ρ2, ρ3, ρ4, ρ5 - denseness of cores material, kg/m3, γ1, γ2, γ3, γ4, γ5 - volumetric share of cores material, kg/m3.
EFFECT: higher efficiency, broader range of functional capabilities.
FIELD: technologies for testing properties of materials.
SUBSTANCE: in method for determining compositions of friable condensed-filled-separated type systems in fractions with sizes of cores D1>D2>…>Dn-1>Dn when D2/D1, D3D2,…,Dn/Dn-1 greater than 0.155, d1>d2>…>dn-1>dn when d2/d1, d3/d2,…,dn/dn-1 less than 0.155, where Dn>d1, cores material denseness is determined, as well as volumetric mass, emptiness value and average fraction cores size, compaction level value is calculated, composition of mixture of condensed type is determined on basis of fractions with core sizes D, emptiness value and average cores size of said mixture, value of grade of filling of empty spaces of mixture with fractions with core sizes d is calculated, value of separation level of condensed mixture by fractions with core sizes d is calculated, and compositions of friable systems of condensed-filled-separate type are determined from formulae in following order: , m3, where Vmx - volume of mixture of condensed type on basis of fractions with core sizes D, m3; α - coefficient for condensed type mixture separation by fractions with core sizes d; Vd - volume of fraction with sizes of cores d, m3; Y - level of filling of empty spaces of compacted type by cores of fractions with sizes d, limits of value measurement being 0<Y≤1; Vemp - condensed type mixture emptiness value - relation of empty spaces volume to mixture volume, Dav.mx2 - average size of cores in a mixture.
EFFECT: higher precision, lower laboriousness.
FIELD: nondestructive testing.
SUBSTANCE: method comprises drilling hole in concrete, securing anchor device inside the hole, and pulling out the anchor with applying destroying force. The strength of concreter is determined form the formula , where N is the destroying force, D is the diameter of the specimen, m, and d is the diameter of the hole, m.
EFFECT: enhanced accuracy of determining.
1 dwg, 1 ex
SUBSTANCE: method comprises securing anchor device connected with the instrument in the concrete, applying breaking load, and determining the strength form the breaking load. The concrete is provided with hole and ring groove coaxial to the hole. The depth of the groove is equal to the height of the specimen. The anchor device is then secured in the hole and breaking force is applied by pressing the anchor device until the specimen is spalled. The strength is determined from the formula where N is the breaking load, in N, h is the height of the specimen, in m, D is the diameter of the specimen, in m, and d is the diameter of the hole.
EFFECT: decreased labor consumption.
1 dwg, 1 ex
FIELD: building, particularly to perform nondestructive testing of structure concrete strength.
SUBSTANCE: method involves drilling bore-hole in concrete body; cutting annular groove in concrete body coaxial to bore-hole; arranging metal cylindrical ferrule in annular groove, wherein cylindrical ferrule has dimension comparable with that of sample; securing anchoring head in bore-hole and pressing anchoring head into concrete body up to sample destruction. Concrete strength is determined from the following formula: R = (N·10-6)/2πdh, where R is concrete strength, MPa, N - destructive force, H, h is sample height, m.
EFFECT: possibility to determine physical and mechanical concrete characteristics directly in structure body.