CN214844936U - Device for nondestructive testing of steel fiber content and distribution in steel fiber concrete - Google Patents
Device for nondestructive testing of steel fiber content and distribution in steel fiber concrete Download PDFInfo
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- CN214844936U CN214844936U CN202120901170.2U CN202120901170U CN214844936U CN 214844936 U CN214844936 U CN 214844936U CN 202120901170 U CN202120901170 U CN 202120901170U CN 214844936 U CN214844936 U CN 214844936U
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Abstract
The utility model provides a device of steel fibre content and distribution in nondestructive test steel fibre concrete, it includes: an insulating base; the concrete test block to be detected is placed in the hollow insulating shell, and the outer side surface of the hollow insulating shell is provided with two binding posts; the lead is wound on the outer side surface of the hollow insulating shell in parallel, and two ends of the lead are respectively connected to the wiring terminals; and the inductance tester is provided with two jointing clamps which are connected with the binding posts so as to form a detection circuit with the lead. The utility model provides a device of steel fibre content and distribution in nondestructive test concrete need not to destroy the steel fibre concrete piece and can accomplish the test, not only can record steel fibre's content in the steel fibre concrete, can also survey the distribution of steel fibre wherein.
Description
Technical Field
The utility model belongs to civil engineering material detection area especially involves a device of steel fibre content and distribution in the nondestructive test steel fibre concrete.
Background
In contemporary buildings, steel fibre concrete is increasingly used in construction. The steel fiber concrete is a novel multiphase composite material formed by doping short steel fibers which are distributed disorderly into common concrete. The disorderly distributed steel fibers can effectively prevent the micro cracks in the concrete from expanding and the macro cracks from forming, and obviously improve the tensile, bending, impact and fatigue resistance of the concrete. And compared with common concrete, the steel fiber concrete has better bending resistance, crack resistance, shock resistance and other performances. With the increasing use of steel fiber concrete in the fields of tunnels, roads, bridges and the like, it becomes more important to provide more information for the use thereof through testing. For steel fiber concrete, the influence of the content and the distribution direction of steel fibers on the mechanical property of the structure is huge, so that in the test of the steel fiber concrete, the content and the distribution of the steel fibers need to be obtained in addition to the traditional mechanical experiment, so as to provide a basis for the quality control and the structural design of the steel fiber concrete.
At present, the method for detecting the content of steel fibers in steel fiber concrete mainly comprises the steps of crushing a steel fiber concrete test piece to be detected by using a pressure testing machine, separating steel fibers, cleaning, drying and weighing the steel fiber concrete test piece, and then calculating the content of the fibers in the steel fiber concrete according to the relative mass of the fibers and the concrete (patent number: CN 201310377024.4). The detection by the method is very visual, but has a plurality of defects, such as high cost, environmental pollution caused by the used waste water and large time consumption. In addition, this method also fails to detect the distribution of fibers in the concrete and provides insufficient data for structural design.
First, the direct crushing method can determine the content of the steel fibers but cannot obtain the distribution direction of the steel fibers. The mechanical properties of steel fiber concrete members are not only related to the content of steel fibers, but also are strongly related to the distribution direction of the steel fibers. For example, when a beam member is made of steel fiber reinforced concrete, a large number of beams with steel fibers distributed along the span of the beam will have much better mechanical properties than a large number of beams distributed perpendicular to the span. Therefore, although this method can measure the steel fiber content, it cannot accurately control the quality of the steel fiber concrete member.
Secondly, the direct disruption method is a time-consuming, labor-intensive and uneconomical destructive testing method. To separate the steel fibers from the steel fiber concrete block, some large mechanical equipment is required, for example, a hydraulic press is required to crush the steel fiber concrete block, and a grinder is used to grind the crushed concrete to separate the steel fibers. The series of processes are complex and time-consuming, and large-scale mechanical equipment is expensive, so that the method is not suitable for popularization and field detection.
Therefore, the device and the method for non-destructive testing of the content and distribution of the steel fibers in the steel fiber concrete are provided, and have very important significance for structural design and quality control.
SUMMERY OF THE UTILITY MODEL
It is an object of the present invention to provide a device for non-destructive testing of the content and distribution of steel fibres in concrete, and to provide at least the advantages that will be explained later.
Another object of the utility model is to provide a device of steel fibre content and distribution in nondestructive test concrete need not to destroy the steel fibre concrete piece and can accomplish the test, not only can record steel fibre content in the steel fibre concrete, can also survey the distribution of steel fibre wherein.
The technical scheme of the utility model as follows:
device of non-destructive testing steel fibre content and distribution in steel fibre concrete, it includes:
an insulating base;
the concrete test block to be detected is placed in the hollow insulating shell, and the outer side surface of the hollow insulating shell is provided with two binding posts;
the lead is wound on the outer side surface of the hollow insulating shell in parallel, and two ends of the lead are respectively connected to the wiring terminals;
and the inductance tester is provided with two jointing clamps which are connected with the binding posts so as to form a detection circuit with the lead.
Preferably, in the apparatus for non-destructive testing of steel fiber content and distribution in steel fiber concrete, the inductance tester is a digital bridge tester, and supplies a current with a frequency of 1kHz and a voltage of 1V to the wire.
Preferably, in the apparatus for non-destructive testing of steel fiber content and distribution in steel fiber reinforced concrete, the insulation base comprises:
a base plate;
the supporting block is arranged on the upper surface of the bottom plate, and the hollow insulating shell is sleeved on the periphery of the supporting block;
and the accommodating groove is arranged on the upper surface of the supporting block and used for placing the concrete test block to be detected.
Preferably, in the device for non-destructive testing of the content and distribution of steel fibers in steel fiber reinforced concrete,
the hollow insulating shell is of a hollow cylinder structure with an upper opening and a lower opening and communicated with the inside;
the two binding posts are two bolts;
the two groups of wires are wound on the outer side surface of the hollow insulating shell.
Preferably, in the device for non-destructive testing of the content and distribution of steel fibers in steel fiber reinforced concrete,
the height of the hollow insulating shell is 200mm, the inner diameter is 235mm, and the wall thickness is 5 mm;
the diameter of the bolt is 4 mm;
the wire is copper wire, and the diameter is 0.3mm, and every group the winding number of turns of wire is 1200 circles, and two sets of the distance between the wire is 130 mm.
Preferably, in the device for non-destructive testing of the content and distribution of steel fibers in steel fiber reinforced concrete,
the hollow insulating shell is a cuboid hollow column, and the cross section of the hollow insulating shell is square;
the three groups of wires are respectively wound on the upper part, the middle part and the lower part of the hollow insulating shell.
Preferably, in the device for non-destructive testing of the content and distribution of steel fibers in steel fiber reinforced concrete,
the height of the hollow insulating shell is 150mm, the thickness of the hollow insulating shell is 5mm, and the side length of an inner hole is 17 mm;
the wire is the copper line, and the diameter is 0.2mm, and the total length is 1600m, and the interval between three group's wires is 65mm, every group the winding width of wire is 20 mm.
The method for nondestructively detecting the content and distribution of steel fibers in concrete comprises the following steps:
the device for nondestructively detecting the content and distribution of the steel fibers in the steel fiber concrete is installed and connected with a detection circuit to obtain an initial inductance value L;
putting a concrete test block with known steel fiber content to obtain a test inductance coefficient value, and calculating according to the initial inductance coefficient value, the test inductance coefficient value and the known steel fiber content to obtain a proportional relation between the steel fiber content and an inductance coefficient change value;
and putting the concrete test block to be detected into the concrete test block to obtain the current inductance coefficient value, and calculating the steel fiber content and the direction coefficient in the concrete test block to be detected according to the current inductance coefficient value and the proportional relation between the steel fiber content and the inductance coefficient change value.
Preferably, in the method for non-destructive testing of the content and distribution of steel fibers in steel fiber reinforced concrete,
selecting a cubic concrete test block with the same steel fiber as the concrete test block to be detected, defining three mutually vertical surfaces of the cubic concrete test block as an X surface, a Y surface and a Z surface respectively, and detecting the X surface, the Y surface and the Z surface upwards respectively to obtain LX、LYAnd LZSubtracting the initial inductance value L to obtain the inductance increment L in each directionX、∆LYAnd LZSumming to obtain the sum of the inductance increment L;
breaking the test block, separating steel fibers to obtain the mass M of the steel fibers, and dividing the mass M by the volume V of the test block to obtain the content C of the steel fibers of the test blockf；
Calculating the proportional relation omega, omega = C of the steel fiber content of the steel fiber and the inductance coefficient change valuef/∆L；
Respectively treatDetecting the upward X surface, Y surface and Z surface of the concrete test block to obtain LXj、LYjAnd LZjSubtracting the initial inductance value L to obtain the inductance increment L in each directionXj、∆LYjAnd LZjSumming to obtain the sum of the inductance increment Lj;
calculating to obtain the steel fiber content C of the concrete test block to be detectedfj，Cfj=ω. ∆Lj；
Calculating to obtain the direction coefficients of the steel fibers in the X axis, the Y axis and the Z axis and the contribution degree of the steel fibers to each axis;
in the formula etaiA direction coefficient indicating a direction of an i-axis; Δ LiIndicating an inductance increment in the i-axis direction; Δ L represents the sum of the inductance increments in three directions; gamma is the shape coefficient of the steel fiber and is a constant;
in the formula, CiIndicating the degree of contribution of the steel fibers to the i-axis performance.
Preferably, in the method for non-destructive testing of the content and distribution of steel fibers in steel fiber reinforced concrete,
the concrete test block is cylindrical or cubic, and the steel fiber content calculation method comprises the following steps:
in the formula, CfThe fiber content in the steel fiber concrete test piece is shown; beta is the proportional coefficient of the content of the steel fiber and the change value of the inductance coefficient; l isiThe inductance change value in each direction is obtained; l ise,iThe equivalent inductance change value in each direction is obtained; b isv,iFor magnetic induction intensity on the test piece bodyIntegration within the product range; l ise,iIs the sum of the equivalent inductance coefficient changes; etaiIs a directional coefficient; upsilon and mu are correction coefficients; gamma is a shape factor.
The principle of the utility model is that: according to faraday's law of electromagnetic induction, the inductance of a coil depends on the shape of the coil and the permeability of the internal material. The test firstly measures the inductance coefficient of the coil under the vacuum condition, and after the steel fiber concrete test piece is placed, the components such as cement, aggregate and the like have no ferromagnetism, so the test piece can be regarded as vacuum and does not influence the inductance coefficient of the coil; the steel fiber has ferromagnetism, and influences the inductance coefficient of the coil to change the value of the coil, so that the content and distribution of the steel fiber in the steel fiber concrete can be obtained through the change of the inductance coefficient.
The utility model has the advantages that: the testing device has the advantages of small volume, light weight, portability, simple use and quick operation, and can be used for in-situ testing. The used coil can be made by hands of testing personnel, the manufacturing cost is low, and the coil can be repeatedly used. The test piece measured by the device is not limited in shape and age, and can be used for concrete just poured or concrete solidified after setting.
The utility model provides a device of steel fibre content and distribution in nondestructive test steel fibre concrete not only can incline and get steel fibre's content in the steel fibre concrete, can also survey the distribution of steel fibre wherein.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment of an apparatus for nondestructive testing of steel fiber content and distribution in steel fiber concrete provided by the present invention;
FIG. 2 is a schematic structural diagram of an insulating base in an embodiment of the apparatus for nondestructive testing of steel fiber content and distribution in steel fiber concrete provided by the present invention;
FIG. 3 is a schematic structural diagram of a hollow insulated housing in an embodiment of the apparatus for nondestructive testing of steel fiber content and distribution in steel fiber concrete provided by the present invention;
fig. 4 is a schematic structural diagram of a hollow insulating shell in another embodiment of the apparatus for nondestructive testing of steel fiber content and distribution in steel fiber concrete provided by the present invention.
Detailed Description
The present invention is further described in detail below with reference to the drawings so that those skilled in the art can implement the invention with reference to the description.
It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.
As shown in FIG. 1, the utility model provides a device of steel fibre content and distribution in nondestructive test steel fibre concrete, it includes:
an insulating base 2;
the concrete test block detection device comprises a hollow insulating shell 1, a detection device and a detection device, wherein the hollow insulating shell 1 is positioned above an insulating base 2 and is internally provided with a concrete test block to be detected, and two binding posts are arranged on the outer side surface of the hollow insulating shell;
the lead wires are wound on the outer side surface of the hollow insulating shell 1 in parallel, and two ends of the lead wires are connected to the wiring terminals respectively;
and the inductance tester 3 is provided with two jointing clamps which are connected with the jointing posts so as to form a detection circuit with the lead.
In an embodiment of the device for nondestructive testing of steel fiber content and distribution in steel fiber concrete, the inductance tester 3 is a digital bridge tester, and the wire provides current with frequency of 1kHz and 1V voltage.
As shown in fig. 2, in an embodiment of the apparatus for nondestructive testing of steel fiber content and distribution in steel fiber concrete provided by the present invention, the insulation base 2 includes:
a base plate;
the supporting block is arranged on the upper surface of the bottom plate, and the hollow insulating shell is sleeved on the periphery of the supporting block;
and the accommodating groove is arranged on the upper surface of the supporting block and used for placing the concrete test block to be detected.
As shown in fig. 3, in an embodiment of the apparatus for non-destructive testing of steel fiber content and distribution in steel fiber concrete provided by the present invention,
the hollow insulating shell is of a hollow cylinder structure with an upper opening and a lower opening and communicated with the inside;
the two binding posts are two bolts;
the two groups of wires are wound on the outer side surface of the hollow insulating shell.
In one embodiment of the device for nondestructive testing of steel fiber content and distribution in steel fiber concrete provided by the utility model,
the height of the hollow insulating shell is 200mm, the inner diameter is 235mm, and the wall thickness is 5 mm;
the diameter of the bolt is 4 mm;
the wire is copper wire, and the diameter is 0.3mm, and every group the winding number of turns of wire is 1200 circles, and two sets of the distance between the wire is 130 mm.
The embodiment is suitable for the cylindrical or cubic steel fiber concrete test block.
As shown in fig. 4, in an embodiment of the apparatus for non-destructive testing of steel fiber content and distribution in steel fiber concrete provided by the present invention,
the hollow insulating shell is a cuboid hollow column, and the cross section of the hollow insulating shell is square;
the three groups of wires are respectively wound on the upper part, the middle part and the lower part of the hollow insulating shell.
In one embodiment of the device for nondestructive testing of steel fiber content and distribution in steel fiber concrete provided by the utility model,
the height of the hollow insulating shell is 150mm, the thickness of the hollow insulating shell is 5mm, and the side length of an inner hole is 17 mm;
the wire is the copper line, and the diameter is 0.2mm, and the total length is 1600m, and the interval between three group's wires is 65mm, every group the winding width of wire is 20 mm.
The embodiment is suitable for cube test blocks.
The principle of the utility model is as follows:
indirectly testing the content and the distribution direction of the steel fibers by utilizing the relationship between the inductance change of the electrified hollow coil and the content and the distribution direction of the fibers contained in the coil; for an air-core coil with fixed winding materials, fixed turn numbers, fixed section shapes and fixed power-on states, the inductance of the air-core coil is only related to materials contained in a magnetic field generated by the coil, the larger the magnetic permeability of the materials is, the larger the inductance of the coil is, and the direct proportional function relationship is formed between the inductance and the magnetic permeability of the materials; meanwhile, only the steel fibers in the steel fiber concrete belong to ferromagnetic materials, so that after the steel fiber concrete is placed in the energized hollow coil, the increase of the coil inductance can be only considered to be caused by the steel fibers, and the more the content of the steel fibers is, the more the inductance increment is; in addition, the inductance increase is greatest if the direction of alignment of the steel fibers is parallel to the magnetic field lines, and is smallest if the direction of alignment of the fibers is perpendicular to the magnetic field lines, which is about one ninth of the direction of alignment, so that the inductance increase also reflects the direction of fiber distribution; meanwhile, three groups of coils are respectively wound on the upper part, the middle part and the lower part of the cuboid hollow column, so that a uniform magnetic field can be generated in the coils, the difference of inductance change caused by the difference of the positions of the steel fibers is eliminated, and the inductance change is only related to the content and the distribution direction of the steel fibers; for the cubic test block of steel fiber concrete in any age, inductance increment in the direction of three axes X, Y, Z perpendicular to three mutually perpendicular surfaces is respectively measured, and theories and experiments show that the sum of the three increments is in a direct proportional function relationship with the content of steel fiber.
The utility model provides a steel fibre content and distribution device in nondestructive test concrete, its working process includes following step:
the device for nondestructively detecting the content and distribution of the steel fibers in the steel fiber concrete is installed and connected with a detection circuit to obtain an initial inductance value L;
putting a concrete test block with known steel fiber content to obtain a test inductance coefficient value, and calculating according to the initial inductance coefficient value, the test inductance coefficient value and the known steel fiber content to obtain a proportional relation between the steel fiber content and an inductance coefficient change value;
and putting the concrete test block to be detected into the concrete test block to obtain the current inductance coefficient value, and calculating the steel fiber content and the direction coefficient in the concrete test block to be detected according to the current inductance coefficient value and the proportional relation between the steel fiber content and the inductance coefficient change value.
Example 1
When the hollow insulating shell is a cuboid hollow column, the device for nondestructive testing of the content and distribution of the steel fibers in the steel fiber concrete comprises a digital bridge tester and the cuboid hollow column, wherein double-row two-linked copper binding posts are arranged on the cuboid hollow column and are wound with coils, and the coils are connected with the double-row two-linked copper binding posts; the digital bridge tester is connected with the double-row two-connection copper binding post through a lead, is used for testing the inductance of the coil, generates current with the frequency of 1kHz and 1V voltage and supplies power to the coil.
The coil is the copper line, and the parallel winding is in the hollow post outside of cuboid, and the coil divide into three groups, twines respectively in upper portion, middle part, the bottom of the hollow post of cuboid.
The copper wire is an insulated red copper wire, the diameter of the copper wire is 0.2mm, the total length of all the copper wires is 1600m, three groups of coils are uniformly distributed, the winding directions of the three groups of coils are consistent, the distance between the three groups of coils is 6.5cm, the width of each group of coils is 2cm after the three groups of coils are wound on a cuboid hollow column, the three groups of coils are connected in parallel, the starting ends of the three groups of coils are all connected to the same connector of two rows of two-linkage copper wiring terminals, and the tail ends of the three groups of coils are connected to the other connector so as to ensure that the current directions in the windings are consistent.
The rectangular hollow column is made of acrylic organic glass material, the height is 15cm, and the thickness is 5 mm; the cross section of the cuboid hollow column is square, and the length of the inner side of the square is 17 cm.
(1) The test piece requirements are as follows:
the method is suitable for detecting the steel fiber concrete cube block with the side length of 15 cm. The cube block can be made directly from the mold or by coring from other large test pieces. The concrete may be hardened concrete or unhardened concrete. When the unhardened concrete is detected, a cubic container is needed to contain the concrete.
(2) ω in the measurement formula (1):
ω=Cf/∆L (1)
in the formula: cfRepresents the steel fiber content; omega is a constant, the value is different for different types of steel fibers, and the value is unchanged for the same type of steel fibers and is measured by a test; Δ L is the sum of the inductance increments in the three axial directions.
Three mutually vertical surfaces of a concrete cube are respectively set as an X surface, a Y surface and a Z surface, the axes vertical to the respective surfaces are respectively an X axis, a Y axis and a Z axis, a digital bridge tester is communicated with a power supply, meanwhile, a digital bridge is connected to a binding post of a cuboid through a lead, the digital bridge tester is adjusted to a sensing state according to instructions, and the instrument is placed at a place without ferromagnetic materials around to start measurement.
Firstly, measuring the coil inductance L when no object exists in the coil, respectively placing the X surface, the Y surface and the Z surface into the coil in an upward mode, testing the respective inductance, testing each surface for three times, and taking the average value to obtain the LX、LYAnd LZSubtracting the initial inductance L to obtain the inductance increment L in each directionX、∆LYAnd LZAnd summing to obtain the sum of the inductance increment L. Crushing the test block, separating steel fiber, weighing to obtain steel fiber weight M, and dividing by the test block volume V to obtain steel fiber content CfThe constant ω can be obtained from the formula (1).
(3) And (3) detection process:
a. preparing a test piece
The test pieces can be divided into concrete mixes and hardened concrete blocks. For concrete mixture, a square container is required to be used for containing, and then detection is carried out, and for hardened concrete blocks, the concrete mixture can be obtained through the following three ways:
the first mode is as follows: the test block is directly poured by a cube mold with the side length of 150mm, and is cured under the standard curing conditions of the temperature of 20 +/-2 ℃ and the relative humidity of more than 95 percent, and the test block can be detected at any age after the concrete is solidified and hardened.
The second mode is as follows: a cuboid test block can be poured by a mould, the test block is maintained for 28 days under the standard maintenance conditions that the temperature is 20 +/-2 ℃ and the relative humidity is more than 95 percent, and then a cutting machine is used for cutting to obtain the test block with the side length of 150 mm. It should be noted that, during cutting, concrete in a range that two ends of the long edge of the cuboid test block are larger than the length of the steel fiber needs to be cut off first, so as to avoid the influence of the edge effect of the mold.
The third mode is as follows: the core cutting can be carried out on other prefabricated parts which are already hardened to obtain test blocks with the side length of 150 mm.
b. Preparing instrument
The method comprises the steps of placing a rectangular hollow column wound with a coil at a place without ferromagnetic materials around, switching on a digital bridge tester, adjusting to an inductance measuring mode according to a mode in a specification of the digital bridge tester, selecting a manual mode for triggering, then resetting, and connecting a lead of the digital bridge tester to a double-row duplex copper binding post on the rectangular hollow column to connect the coil.
c. Detection of
Three mutually perpendicular surfaces of the concrete cube are respectively set as an X surface, a Y surface and a Z surface, and axes perpendicular to the surfaces are respectively an X axis, a Y axis and a Z axis. When measuring each quantity, the measurement needs to be carried out three times, and the effect of measuring three times can be achieved by manually triggering the digital bridge tester three times.
Measuring initial inductance when no object is placed in the cuboid hollow column, manually triggering for three times, and respectively recording inductance L of each time1、L2And L3. Placing the test block with the X surface facing upwards into the center of the cuboid hollow column, measuring the inductance in the state, manually triggering for three times, and respectively recording the inductance L of each timeX1、LX2And LX3Respectively placing Y, Z face upward in the center of the rectangular hollow column, and measuring Y, Z axis inductance L by the same methodY1、LY2、LY3、LZ1、LZ2And LZ3。
(4) And (3) processing data to obtain the following results:
to L1、L2And L3Averaging to obtain initial inductanceLTo L forX1、LX2And LX3Averaging value of X-axis direction inductorL X Similarly, the inductance in the direction of Y, Z axis is obtainedL Y 、L Z 。L X 、L Y 、L Z Subtracting the initial inductances, respectivelyLThe available three-axis direction individual inductance incrementX、∆LYAnd LZAnd adding the values to obtain the sum L of the inductance increment in the three axial directions, and obtaining the content of the steel fiber by using the parameter omega measured by the steel fiber in the same type through the formula (1).
Meanwhile, the measured data, the formula (2) and the formula (3) can be used for obtaining the direction coefficients of the steel fibers in the X axis, the Y axis and the Z axis and the contribution degree of the steel fibers to each axis.
In the formula etaiA direction coefficient indicating a direction of an i-axis; Δ LiIndicating an inductance increment in the i-axis direction; Δ L represents the sum of the inductance increments in three directions; gamma is the shape coefficient of the steel fiber, and omega is a constant;
in the formula: ciRepresenting steel fibre pairs
The degree of contribution of the axle performance.
The content of the steel fibers in the steel fiber concrete can be measured, and the distribution directions of the steel fibers can be judged, so that the mechanical properties of the steel fibers can be better judged; in addition, the testing method is simple, the steel fiber concrete can be tested on a construction site only by measuring the omega value of one type of steel fiber through a small number of test blocks in a laboratory, the testing time is short, and the device is small, exquisite, light and low in price and is suitable for being popularized on the construction site.
Example 2
The utility model provides a device of steel fibre content and distribution in nondestructive test steel fibre concrete, including coil, base and digital electric bridge tester, the coil comprises the winding of copper line on the casing, and the coil is placed on the base, is connected with the electric bridge tester through the wiring.
The shell is a hollow cylinder with an upper opening and a lower opening and communicated with the inside, the size of the hollow cylinder is 20cm in height, the inner diameter of the hollow cylinder is 23.5cm, the thickness of the hollow cylinder is 5mm, the hollow cylinder is made of acrylic organic glass, a binding post is arranged in the middle of the outer wall of the hollow cylinder, and the binding post is a double-row two-way binding post with the diameter of 4 mm.
The diameter of the copper wire is 0.3 mm.
The copper wire is divided into two coils which are wound on the outer surface of the shell in the same direction, each coil of copper wire is wound for 1200 circles in a non-uniform mode, the starting ends of the two coils of copper wires are connected to the same binding post, the tail ends of the two coils of copper wires are connected to the other binding post, and the distance between the two coils of copper wires is 13 cm.
The base is formed by vertically laminating two cylinders with different sizes, the diameter of the upper-layer cylinder is the inner diameter of the plastic shell, and a square groove of 16cm by 16cm is formed in the upper-layer cylinder; the base is made of acrylic organic glass.
And one end connector of the wiring is provided with two electric clamps for connecting wiring terminals on the coil.
The digital bridge tester can generate current with the frequency of 1kHz and voltage of 1V, supplies power to the coil, and can measure the inductance coefficient of the coil.
The implementation process is as follows: placing the coil on a base, generating a uniform induction magnetic field in the coil (1) after the coil is electrified by a digital bridge tester, and recording the inductance index reading of the digital bridge tester at the moment; then putting a steel fiber concrete test block with known fiber content, measuring inductance coefficient change values of the test block in all directions by using a digital bridge tester, and calculating to obtain a proportional relation beta of the sum of the fiber content and the inductance coefficient change; after the steel fiber concrete test block with unknown content is placed, the inductance coefficient change value is measured by the same method, and the content and distribution of the steel fibers in the steel fiber concrete test block can be measured by a formula.
The concrete test block is cylindrical or cubic, and the calculation method of the content and the distribution of the steel fibers comprises the following steps:
in the formula, CfThe fiber content in the steel fiber concrete test piece is shown; beta is the proportional coefficient of the content of the steel fiber and the change value of the inductance coefficient; l isiThe inductance change value in each direction is obtained; l ise,iThe equivalent inductance change value in each direction is obtained; b isv,iThe integral of the magnetic induction intensity in the volume range of the test piece is obtained; l ise,iIs the sum of the equivalent inductance coefficient changes; etaiIs a directional coefficient; upsilon and mu are correction coefficients; gamma is a shape coefficient, and the value range of gamma refers to table 1.
The utility model provides a device of steel fibre content and distribution in nondestructive test steel fibre concrete has small, and the quality is light, carries on one's side, simple to use, and the operation is fast, multiple functional advantage.
The utility model provides a device of steel fibre content and distribution in nondestructive test steel fibre concrete can be used for the normal position test. The used coil can be made by hands of testing personnel, the manufacturing cost is low, and the coil can be repeatedly used. The test piece measured by the device is not limited to the age of concrete, and can be used for concrete just poured or concrete which is solidified.
While the embodiments of the invention have been described above, it is not intended to be limited to the details shown, or described, but rather to cover all modifications, which would come within the scope of the appended claims, and all changes which come within the meaning and range of equivalency of the art are therefore intended to be embraced therein.
Claims (7)
1. Device of non-destructive testing steel fibre content and distribution in steel fibre concrete, its characterized in that includes:
an insulating base;
the concrete test block to be detected is placed in the hollow insulating shell, and the outer side surface of the hollow insulating shell is provided with two binding posts;
the lead is wound on the outer side surface of the hollow insulating shell in parallel, and two ends of the lead are respectively connected to the wiring terminals;
and the inductance tester is provided with two jointing clamps which are connected with the binding posts so as to form a detection circuit with the lead.
2. The apparatus for non-destructive testing of steel fiber content and distribution in steel fiber concrete according to claim 1, wherein said inductance tester is a digital bridge tester supplying a current with a frequency of 1kHz and a voltage of 1V to said wire.
3. The apparatus for non-destructive testing of steel fiber content and distribution in steel fiber concrete according to claim 2, wherein said insulating base comprises:
a base plate;
the supporting block is arranged on the upper surface of the bottom plate, and the hollow insulating shell is sleeved on the periphery of the supporting block;
and the accommodating groove is arranged on the upper surface of the supporting block and used for placing the concrete test block to be detected.
4. The apparatus for non-destructive testing of steel fiber content and distribution in steel fiber concrete according to claim 3,
the hollow insulating shell is of a hollow cylinder structure with an upper opening and a lower opening and communicated with the inside;
the two binding posts are two bolts;
the two groups of wires are wound on the outer side surface of the hollow insulating shell.
5. The apparatus for non-destructive testing of steel fiber content and distribution in steel fiber concrete according to claim 4,
the height of the hollow insulating shell is 200mm, the inner diameter is 235mm, and the wall thickness is 5 mm;
the diameter of the bolt is 4 mm;
the wire is copper wire, and the diameter is 0.3mm, and every group the winding number of turns of wire is 1200 circles, and two sets of the distance between the wire is 130 mm.
6. The apparatus for non-destructive testing of steel fiber content and distribution in steel fiber concrete according to claim 3,
the hollow insulating shell is a cuboid hollow column, and the cross section of the hollow insulating shell is square;
the three groups of wires are respectively wound on the upper part, the middle part and the lower part of the hollow insulating shell.
7. The apparatus for non-destructive testing of steel fiber content and distribution in steel fiber concrete according to claim 6,
the height of the hollow insulating shell is 150mm, the thickness of the hollow insulating shell is 5mm, and the side length of an inner hole is 17 mm;
the wire is the copper line, and the diameter is 0.2mm, and the total length is 1600m, and the interval between three group's wires is 65mm, every group the winding width of wire is 20 mm.
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