CN111024478A - Steel fiber pull-out test piece pouring mold, pouring method and bonding slippage testing method - Google Patents
Steel fiber pull-out test piece pouring mold, pouring method and bonding slippage testing method Download PDFInfo
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- CN111024478A CN111024478A CN201911375381.0A CN201911375381A CN111024478A CN 111024478 A CN111024478 A CN 111024478A CN 201911375381 A CN201911375381 A CN 201911375381A CN 111024478 A CN111024478 A CN 111024478A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
- G01B5/18—Measuring arrangements characterised by the use of mechanical techniques for measuring depth
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
- G01B5/24—Measuring arrangements characterised by the use of mechanical techniques for measuring angles or tapers; for testing the alignment of axes
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N19/00—Investigating materials by mechanical methods
- G01N19/04—Measuring adhesive force between materials, e.g. of sealing tape, of coating
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/36—Embedding or analogous mounting of samples
- G01N2001/366—Moulds; Demoulding
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Abstract
The invention discloses a steel fiber pull-out test piece pouring mold, a pouring method and a bonding slippage testing method, wherein the mold comprises a bottom plate (1), a pair of top plates (2), a scale plate (3), a bolt and nut (4), a bolt hole (5) and a slice (7); the pair of top plates and the scale plate are arranged on the bottom plate through bolt holes by bolts and nuts, and the scale plate is positioned between the pair of top plates; be equipped with the test piece that is used for concreting on the roof and pour fretwork (21), the fretwork is pour to the test piece and runs through the roof, is equipped with scale mark (8) on the scale plate, and the open end that the fretwork was pour to the section cover test piece, and the fretwork is pour to steel fibre one end along the scale mark insertion test piece, and the other end runs through the section. The invention can change the type, the angle and the burial depth of the test piece, and improve the manufacturing efficiency and the pouring quality of the test piece; the clamping test piece can be stably clamped during testing, more accurate fiber bonding sliding relation can be measured, the installation, the disassembly and the cleaning are convenient, and the testing cost is effectively reduced.
Description
Technical Field
The invention relates to a test piece die, a test piece pouring method and a performance testing method for an ultrahigh-performance concrete material, in particular to a steel fiber pull-out test piece pouring die, a pouring method and a bonding slippage testing method.
Background
Concrete is one of the most used civil engineering materials. With the construction of large-scale engineering structures, the common concrete can not meet the requirements of engineering structures under complex environments and load action more and more due to the problems of large brittleness, easy cracking, low strength, long maintenance period and the like. High strength concrete, while capable of increasing the compressive strength of the concrete, does not improve the brittleness. Fiber concrete can improve the ductility of concrete, but the tensile stress-strain curve of fiber concrete is in the form of strain softening. In recent years, the ultrahigh-performance concrete with the compressive strength not lower than 150MPa is prepared by removing coarse aggregates, adding high-performance steel fibers and a water reducing agent, adding a mineral admixture and the like, multiple cracks are generated under the action of tensile stress, and a strain hardening form is realized by a tensile stress-strain curve, so that the ultrahigh-strength ultrahigh-ductility ultrahigh-durability fiber-reinforced cement-based composite material is a fiber-reinforced cement-based composite material and is gradually applied to the construction of complex civil engineering structures.
The key factor influencing the mechanical property of the ultra-high performance concrete is the interface bonding property of the high performance steel fiber and the cement matrix. In the initial stage of stress, the steel fiber and the cement matrix bear external force together; after the matrix is cracked, fibers among cracks continue to bridge the matrix, so that the tensile strain hardening performance and the high strain capacity of the ultra-high performance concrete are ensured. Therefore, it is important to evaluate the interfacial adhesion between the fiber and the cement matrix. Among the various conventional evaluation methods, the single fiber pull-out test is the most commonly used test method. By changing the fiber type, the fiber burial depth, the fiber angle and the matrix type, the whole process of pulling out a single steel fiber from the matrix can be observed, so that a test basis is provided for researching the tensile strain hardening mechanism of the ultra-high performance concrete. The single fiber drawing test generally adopts 2 methods of single-side drawing and double-side drawing, and the test result is generally a drawing force-fiber slip curve.
At present, the manufacturing method of the single fiber drawing test piece in the prior art still has the following defects. Firstly, the single fiber pulling-out test piece manufactured in the prior art is mostly a prism test piece, and a chuck of a testing machine is difficult to clamp, so that the interface between the fiber and a matrix is easy to damage. Secondly, the tester usually needs to process a set of mold for the single-sided and double-sided test pieces respectively, which causes waste of material and working hours. Thirdly, because of the small size of the fibers, it takes a lot of time and effort to position the fibers and take other measures to avoid the bonding of the two side substrates in order to determine the burial depth and angle of the fibers, especially in the double-sided extraction, and also to avoid the bonding of the two side substrates of the fibers. Finally, because the steel fiber pulling load is small, the fiber slippage is small, the measuring range of the load sensor of the testing machine is often far larger than the required observation amount, more researchers take the displacement of the cross beam of the testing machine as the fiber slippage, and the measurement error caused by the fiber slippage obviously influences the accuracy of the test result.
Disclosure of Invention
One of the purposes of the invention is to provide a steel fiber pull-out test piece pouring mold, the embedding depth and the embedding angle of steel fibers can be flexibly adjusted through the scale marks and the two scale plates, the type of a test piece can be changed, and the test piece meeting various test requirements can be simply, conveniently and quickly manufactured.
The invention also aims to provide a pouring method for the steel fiber pull-out test piece, which forms a test piece pouring hollow space as a collective pouring space through a top plate, a bottom plate, a scale plate and a slice, is simple and convenient to pour, ensures stable clamping of the test piece through a variable cross-section structure, and is convenient for test operation.
The invention also aims to provide a bonding slippage testing method for the steel fiber pull-out test piece, which can quickly realize the fiber-matrix interface bonding performance of the steel fiber pull-out test piece on one side or two sides.
The invention is realized by the following steps:
a steel fiber pull-out test piece pouring mold comprises a bottom plate, a pair of top plates, a scale plate, a bolt and a nut, a bolt hole and a slice; the bottom plate, the pair of top plates and the scale plate are all provided with bolt holes, the pair of top plates are respectively arranged on one surface of the bottom plate through the bolt holes by bolt nuts, the scale plate is arranged on one surface of the bottom plate through the bolt holes by bolt nuts, and the scale plate is positioned between the pair of top plates; the pair of top plates are respectively provided with a test piece pouring hollow for pouring concrete, the test piece pouring hollows on the pair of top plates are oppositely arranged, and the test piece pouring hollows penetrate through the top plates, so that the opening ends of the test piece pouring hollows are positioned on the contact surfaces of the top plates and the scale plates; the scale mark is arranged on the scale plate and is positioned at the open end of the pouring hollow of the test piece; the slice laminating can cover the test piece completely and pour the open end of fretwork on the contact surface of scale plate and roof, and in the fretwork was pour to the test piece was inserted along the scale mark to steel fiber's one end, steel fiber's the other end run through the slice.
The width of the closed end of the cast hollow part of the test piece is larger than that of the open end, so that one end of the cast steel fiber, which is pulled out of the test piece, forms an inverted-cone-shaped variable cross-section end, and the other end of the cast steel fiber forms a fixed cross-section end.
The scale plate include first scale plate and second scale plate, all be equipped with scale mark and bolt hole on first scale plate and the second scale plate, and first scale plate sets up with the laminating of second scale plate and fixes on the bottom plate through the bolt hole through bolt and nut, steel fibre runs through and inserts between first scale plate and second scale plate after the section.
The scale mark is composed of a plurality of nicks, the plurality of nicks are distributed in a fan shape by taking the center of the opening of the pouring hollow of the test piece as the center of a circle, the included angle between two adjacent nicks is 15 degrees, and the measuring range of the plurality of nicks is 0-180 degrees.
A pouring method for a steel fiber pull-out test piece comprises the following steps:
step 11: symmetrically mounting a pair of top plates on one surface of a bottom plate through bolt holes by bolts and nuts;
step 12: placing a first scale plate of the scale plate on one surface of the bottom plate, and respectively matching and attaching two side surfaces of the first scale plate with a pair of top plates;
step 13: one end of the steel fiber is embedded in the test piece pouring hollow of the top plate along the angle direction of the scale mark, and the embedding depth of the steel fiber in the test piece pouring hollow is determined by measuring with a ruler;
step 14: the other end of the steel fiber penetrates through a steel fiber through hole reserved in the slice and is attached to the surface of the first scale plate, and the second scale plate of the scale plate covers the first scale plate and the other end of the steel fiber;
step 15: the scale plate is fixed on the bottom plate through bolt holes by bolts and nuts, so that the slice covers the open end of the test piece pouring hollow of the top plate, and the test piece matrix is poured in the test piece pouring hollow;
step 16: maintaining the test piece matrix test piece poured in the step 15, dismantling the scale plate, releasing the other end of the steel fiber, and completing the drawing of the test piece from the steel fiber on one side;
and step 17: inserting the other end of the steel fiber into the test piece pouring hollow part of the other top plate, and pouring a test piece matrix in the test piece pouring hollow part;
step 18: and (5) maintaining the test piece matrix test piece poured in the step (16), and removing the scale plate and the top plate to complete the drawing-out of the test piece by the steel fibers on the two sides.
In the step 15 and the step 17, before pouring, oil is applied to the inner wall of the pouring space formed by pouring the hollow-out and slicing the test piece, and the concrete is stirred and vibrated during pouring to fill the hollow-out space of the pouring of the test piece with the concrete.
A bonding slippage testing method for a steel fiber pull-out test piece comprises the following steps:
step 21: fixing a steel fiber drawing test piece through a test piece clamp, and mounting a load sensor on the test piece clamp;
step 22: two groups of connecting pieces are symmetrically arranged on two sides of the fixed section end of the steel fiber drawing test piece;
step 23: the two groups of connecting pieces are connected with an extensometer;
step 24: the extensometer and the load sensor are respectively connected with an acquisition system of the testing machine, the extensometer is adjusted to a proper displacement loading speed, and the acquisition system starts loading and data acquisition;
step 25: and when the steel fiber is pulled out from the test piece matrix on one side, stopping the test, storing data, drawing a bonding slip relation curve of the steel fiber, extracting required indexes, and finishing the test.
The test piece clamp comprises a variable cross-section clamp and a fixed cross-section clamp; the variable cross-section end of the single-side steel fiber pulling test piece is fixedly clamped by a variable cross-section clamp, and the fixed cross-section end of the single-side steel fiber pulling test piece is fixedly connected with the fixed cross-section clamp; and the two variable cross-section ends of the steel fiber pulling-out test piece on the two sides are fixedly clamped through the variable cross-section clamp.
The variable cross-section fixture is of a U-shaped structure, the opening width of the U-shaped structure is smaller than the width of the inner side of the U-shaped structure, so that the U-shaped structure can be matched and clamped with the variable cross-section end of the steel fiber pull-out test piece, and a load sensor is installed on the variable cross-section fixture through a fixing piece; the fixed cross-section fixture is provided with a U-shaped groove, a pair of clamping pieces are arranged in the U-shaped groove, and a pair of locking bolt threads are screwed into the fixed cross-section fixture and respectively tightly prop against the clamping pieces, so that the clamping pieces are clamped on two sides of the steel fibers.
Each group of connecting pieces comprises two L-shaped connecting pieces which are symmetrically arranged, one end of each L-shaped connecting piece is arranged at the fixed section end of the steel fiber extraction test piece, the other end of each L-shaped connecting piece is perpendicular to the side wall of the steel fiber extraction test piece, the other ends of the two L-shaped connecting pieces of each group of connecting pieces are parallel to each other, and the distance between the other ends of the two L-shaped connecting pieces is larger than the minimum clamping range of the extensometer.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention can quickly pour the steel fiber pull-out test piece on one side and two sides by only using one set of mould, and the mould has simple structure, convenient assembly, disassembly and cleaning and easy demoulding.
2. The mould can accurately position the embedding angle and the embedding depth of the steel fibers through the scale marks, greatly reduces the preparation work for manufacturing the test piece, effectively reduces the test cost, can adjust the embedding angle through the scale marks according to the actual requirement, can change the type and the embedding depth of the test piece, and has high operation flexibility and wide application range.
3. The die disclosed by the invention can be used for pouring a large number of steel fiber drawing test pieces at one time, so that the test piece manufacturing time is saved, the size is accurate, the test progress can be accelerated, and the test cost is reduced.
4. The steel fiber pulling-out test piece poured by the die can be matched and stably clamped by the clamp through the variable cross-section end and the fixed cross-section end with accurate sizes, so that the stability of the test piece is kept during testing, the test error is effectively reduced, and the probability of interface damage of the fiber and the matrix caused by improper operation is reduced.
5. The test method provided by the invention has the advantages of simple equipment, convenience in installation and simplicity in test operation, is beneficial to efficiently and accurately completing the bonding and sliding test of the fiber-matrix interface, and obviously reduces the error of the test.
Drawings
FIG. 1 is a top view of a steel fiber pull-out specimen casting mold of the present invention;
FIG. 2 is a side cross-sectional view of the steel fiber pull-out specimen casting mold of the present invention;
FIG. 3 is a cross-sectional view of a single-sided steel fiber pull-out specimen cast using the steel fiber pull-out specimen casting method of the present invention;
FIG. 4 is a cross-sectional view of a two-sided steel fiber pull-out specimen cast using the steel fiber pull-out specimen casting method of the present invention;
FIG. 5 is a test state diagram of the bond slip test method of a single-sided steel fiber pull-out specimen of the present invention;
FIG. 6 is a sectional side view of the fixed cross-section jig in the adhesion slip test method of the single-sided steel fiber drawn test piece of the present invention;
FIG. 7 is a test state diagram of the bond slip test method of a double-sided steel fiber pull-out test piece of the present invention;
FIG. 8 is a graph showing a relationship between a bonding slip of steel fibers measured by a bonding slip measuring method of a steel fiber drawn-out test piece on both sides according to the present invention.
In the figure, a bottom plate 1, a top plate 2, a test piece 21, a pouring hollow-out, a scale plate 3, a first scale plate 31, a second scale plate 32, a bolt and a nut 4, a bolt hole 5, steel fibers 6, a section 7, scale lines 8, a test piece pulled out by steel fibers 100, a section-variable clamp 201, a section-fixed clamp 202, a U-shaped groove 2021, a clamping piece 2022, a locking bolt 2023, a connecting piece 300, a extensometer 400, a fixing piece 500 and a load sensor 600 are arranged.
Detailed Description
The invention is further described with reference to the following figures and specific examples.
Referring to fig. 1 and 2, a steel fiber pull-out test piece pouring mold comprises a bottom plate 1, a pair of top plates 2, a scale plate 3, a bolt and a nut 4, a bolt hole 5 and a slice 7; the bottom plate 1, the pair of top plates 2 and the scale plate 3 are all provided with bolt holes 5, the pair of top plates 2 are respectively installed on one surface of the bottom plate 1 through the bolt holes 5 through bolt nuts 4, the scale plate 3 is installed on one surface of the bottom plate 1 through the bolt holes 5 through the bolt nuts 4, and the scale plate 3 is located between the pair of top plates 2; the pair of top plates 2 are respectively provided with a test piece pouring hollow 21 for pouring concrete, the test piece pouring hollow 21 on the pair of top plates 2 are oppositely arranged, and the test piece pouring hollow 21 penetrates through the top plates 2, so that the open ends of the test piece pouring hollow 21 are positioned on the contact surfaces of the top plates 2 and the scale plates 3; the scale mark 8 is arranged on the scale plate 3, and the scale mark 8 is positioned at the opening end of the test piece pouring hollow 21; slice 7 laminating can cover the test piece completely and pour the open end of fretwork 21 on the contact surface of scale 3 and roof 2, and the one end of steel fibre 6 inserts in the test piece pours fretwork 21 along scale mark 8, and the other end of steel fibre 6 runs through slice 7.
The closed end width of the hollow part 21 poured by the test piece is larger than the open end width, one end of the poured steel fiber pulling-out test piece forms an inverted-cone-shaped variable cross-section end, the other end of the poured steel fiber pulling-out test piece forms a fixed cross-section end, and the variable cross-section end and fixed cross-section end structures of the steel fiber pulling-out test piece can be more convenient for the stable clamping of the test piece clamp for the steel fiber pulling-out test piece and are not easy to damage the steel fiber pulling-out test piece.
The scale mark 8 is composed of a plurality of nicks which are distributed in a fan shape by taking the center of the opening of the test piece pouring hollow 21 as the center of a circle. Preferably, the nicks can be processed on the scale plate 3 by a carving machine, the length of the nicks is 15mm, the depth and the width of the nicks are both 0.3mm, the included angle between every two adjacent nicks is 15 degrees, the measuring range of the nicks is 0-180 degrees, and the angle adjustment of the steel fibers 6 is met.
The opening size of the pouring hollow-out 21 is 30 x 14mm, so that the steel fiber 6 can be conveniently arranged.
The total thickness of the first scale plate 31 and the second scale plate 32 is equivalent to the thickness of the top plate 2. Preferably, the first scale plate 31 and the second scale plate 32 are both 7mm thick, and the top plate 2 is 14mm thick.
Preferably, the slice 7 can be a polytetrafluoroethylene film slice with a smooth surface and a reserved steel fiber through hole, the length of the slice 7 is 30mm, the width of the slice 7 is 14mm, the thickness of the slice is 0.1-0.2mm, and the smooth surface of the polytetrafluoroethylene film slice can effectively prevent the cement-based material for pouring from being bonded with the scale plate 3.
Preferably, the thickness of the bottom plate 1 is 6-10mm, the aperture of the bolt hole 5 is 6mm, the bottom plate 1, the pair of top plates 2 and the scale plate 3 can be formed by laser cutting acrylic plates, the bolt holes 5 on the bottom plate 1, the pair of top plates 2 and the scale plate 3 correspond to each other, it is ensured that the pair of top plates 2 and the scale plate 3 can be installed on one surface of the bottom plate 1, and the pair of top plates 2 are symmetrically attached to two sides of the scale plate 3.
Preferably, a plurality of test piece pouring hollows 21 can be arranged on one top plate 2, so that a plurality of steel fiber drawing test pieces can be poured at one time through the pouring mold, the pouring mold is suitable for batch production, and the test progress can be accelerated.
Referring to fig. 3 and 4, a method for casting a steel fiber pull-out test piece includes the following steps:
step 11: a pair of top plates 2 are symmetrically mounted on one surface of a base plate 1 through bolt holes 5 by means of bolt nuts 4.
Step 12: the first scale plate 31 of the scale plate 3 is arranged on one surface of the bottom plate 1, and two side surfaces of the first scale plate 31 are respectively matched and attached with the pair of top plates 2.
Step 13: after the one end of the steel fiber 6 is guided along the 8-degree angle of the scale mark, the steel fiber 6 is embedded into the test piece pouring hollow-out 21 of the top plate 2, according to the test design requirement, the angle of the steel fiber 6 can be adjusted and positioned through the scale mark 8, and the embedding depth of the steel fiber 6 in the test piece pouring hollow-out 21 can be determined and adjusted through ruler measurement, so that the embedding angle and the embedding depth of the steel fiber 6 are accurate, and the accuracy of a bonding slippage test is improved.
Step 14: the other end of the steel fiber 6 penetrates through a steel fiber through hole reserved on the slice 7 and is attached to the surface of the first scale plate 31, the steel fiber 6 can be temporarily fixed by using forceps to prevent the displacement of the steel fiber 6, and the second scale plate 32 of the scale plate 3 covers the other ends of the first scale plate 31 and the steel fiber 6.
Step 15: scale plate 3 passes through bolt and nut 4 and fixes on bottom plate 1 through bolt hole 5 to fix steel fibre 6 between first scale plate 31 and second scale plate 32, make section 7 cover and pour fretwork 21 opening end department at the test piece of a roof 2, and pour the test piece base member in the fretwork 21 is pour to the test piece.
Preferably, before pouring, the inner wall of the pouring space formed by pouring the hollow-out 21 and the section 7 on the test piece can be smeared with oil, so that later-stage demolding is facilitated.
Preferably, the ultra-high performance concrete can be adopted for pouring the matrix material, and the ultra-high performance concrete is properly stirred and vibrated during pouring, so that the hollow-out 21 pouring space of the test piece is filled with the ultra-high performance concrete.
Step 16: and (5) maintaining the test piece matrix poured in the step (15), wherein the maintenance time can be 1 day, removing the scale plate 3, releasing the other end of the steel fiber 6, and completing the pulling of the steel fiber on one side out of the test piece 100.
And step 17: and inserting the other end of the steel fiber 6 into the test piece pouring hollow 21 of the other top plate 2, and pouring a test piece matrix in the test piece pouring hollow 21.
Preferably, before pouring, the inner wall of the pouring space formed by pouring the hollow-out 21 and the section 7 on the test piece can be smeared with oil, so that later-stage demolding is facilitated.
Preferably, the ultra-high performance concrete can be adopted for pouring the matrix material, and the ultra-high performance concrete is properly stirred and vibrated during pouring, so that the hollow-out 21 pouring space of the test piece is filled with the ultra-high performance concrete.
Step 18: and (5) maintaining the test piece matrix poured in the step (16), wherein the maintenance time can be 2 days, and removing the scale plate 3 and the top plate 2 to complete the drawing of the steel fibers from the two sides of the test piece 100.
Referring to fig. 5 and 7, a method for testing adhesion slip of a steel fiber drawn test piece includes the following steps:
step 21: the steel fiber is pulled out of the test piece 100 and fixed by a test piece clamp, and a load sensor 600 is installed on the test piece clamp. The range of the adopted load sensor 600 should be slightly larger than the maximum load of the steel fiber pulling test piece, and the error should be not higher than five ten-thousandth of the range. The test piece clamp can be made of steel materials through laser or linear cutting technology, is high in strength and not prone to deformation, and can reliably and matchingly clamp the steel fibers to pull out the fixed section end and the variable section end of the test piece 100.
The test piece clamp comprises a variable cross-section clamp 201 and a fixed cross-section clamp 202; the variable cross-section end of the single-side steel fiber pulling test piece is fixedly clamped through a variable cross-section clamp 201, and the fixed cross-section end of the single-side steel fiber pulling test piece is fixedly connected with a fixed cross-section clamp 202; the two variable cross-section ends of the steel fiber pulling-out test piece on the two sides are fixedly clamped through a variable cross-section clamp 201; the steel fiber pulling-out test piece 100 on the single side or the two sides can be effectively fixed, the stability of the steel fiber pulling-out test piece 100 is kept conveniently in the test, and the steel fiber pulling-out test piece 100 is not damaged.
The variable cross-section clamp 201 is of a U-shaped structure, the opening width of the U-shaped structure is smaller than the width of the inner side of the U-shaped structure, the U-shaped structure can be matched and clamped with the variable cross-section end of the steel fiber pull-out test piece 100, the steel fiber pull-out test piece is not prone to falling off, and therefore fixing reliability of the steel fiber pull-out test piece 100 is improved. The variable cross-section clamp 201 is provided with a load sensor 600 through a fixing piece 500.
Referring to fig. 6, the fixed-section clamp 202 is provided with a U-shaped groove 2021, a pair of clamping pieces 2022 is disposed in the U-shaped groove 2021, and a pair of locking bolts 2023 are screwed into the fixed-section clamp 202 and tightly abut against the pair of clamping pieces 2022, so that the pair of clamping pieces 2022 are clamped on two sides of the steel fiber 6, thereby ensuring stable clamping of the fixed-section end of the single-side steel fiber pulling-out test piece.
Step 22: two groups of connecting pieces 300 are symmetrically arranged on two sides of the fixed section end of the steel fiber pull-out test piece 100, and the installation method specifically comprises the following steps: two pieces 300 are connected to every group and include the L shape connection piece that two symmetries set up, and the one end of L shape connection piece is passed through 502 glue laminating and is installed the fixed cross section end that the test piece 100 was extracted to the steel fibre, and the lateral wall that the test piece 100 was extracted to the perpendicular steel fibre of the other end of L shape connection piece, and the other end of two L shape connection pieces of every group connecting piece 300 is parallel to each other.
In the test of the steel fiber pull-out test piece 100 on both sides, two L-shaped connecting pieces are symmetrically disposed on the test piece substrates on both sides of the steel fiber pull-out test piece 100, respectively. In the test of the steel fiber pull-out test piece 100 on one side, two L-shaped connecting pieces are symmetrically arranged on the test piece base body of the steel fiber pull-out test piece 100 and the fixed section clamp 202 respectively, and the width of the fixed section clamp 202 is equivalent to that of the fixed section end of the steel fiber pull-out test piece 100 on one side, so that symmetrical installation and uniform stress of the two L-shaped connecting pieces are ensured.
Step 23: the extensometer 400 is connected to both sets of connecting pieces 300, and the minimum clamping range of the extensometer 400 is slightly smaller than the distance between the other ends of the two L-shaped connecting pieces, so that reliable connection between the extensometer 400 and the steel fiber extraction test piece 100 through the connecting pieces 300 is ensured.
Step 24: the extensometer 400 and the load sensor 600 are respectively connected with the acquisition system of the testing machine, the extensometer 400 is adjusted to a proper displacement loading speed, and the acquisition system starts loading and data acquisition. Preferably, the minimum displacement loading speed of the testing machine is not higher than 0.5mm/min, and the testing machine acquisition system can acquire the load sensor data of the load sensor 600 and the deformation data of the extensometer 400. The measuring range of the extensometer 400 is slightly larger than the slippage value which is possibly generated by pulling the steel fiber pulling test piece 100 out, and the precision is not lower than 0.001 mm.
Step 25: and when the steel fiber 6 is pulled out from the test piece matrix on one side, stopping the test, storing data, drawing a bonding slip relation curve of the steel fiber, extracting required indexes, and finishing the test.
In the test of the steel fiber pulling-out test piece 100 on the single side and the steel fiber pulling-out test piece 100 on the two sides, the adopted test piece clamp, the connecting piece 300, the extensometer 400, the testing machine and other equipment, accessories and the like are kept consistent, and the test accuracy is ensured.
Example 1:
the pouring material is selected from ultra-high performance concrete.
The steel fiber type has a diameter of 0.3mm and a length of 25mm, and the end part is hook-shaped.
Steel fiber angle: 0 degree.
Steel fiber burial depth: 5mm and 10 mm.
The size of the polytetrafluoroethylene slice is as follows: the thickness is 0.2mm, the length is 30mm, and the width is 14 mm.
Size of the base plate 1: the length is 230mm, the width is 200mm, and the thickness is 6 mm. The bottom plate 1 is provided with 4 rows of bolt holes 5, the center of the first row of bolt holes 5 is 20mm away from the end part of the bottom plate 1, the distance between the second row of bolt holes 5 and the first row of bolt holes 5 is 40mm, and the third row of bolt holes 5 and the fourth row of bolt holes 5 are symmetrically arranged with respect to the central axis of the first row of bolt holes 5 and the second row of bolt holes 5 in the length direction of the bottom plate 1. The aperture of the bolt hole 5 is 3mm, and the distance between adjacent bolt holes 5 is 70 mm.
Size of the top plate 2: the length is 230mm, the width is 80mm, the thickness is 14mm, two rows of bolt holes 5 are formed in the top plate 2, the distance between the centers of the bolt holes 5 and the end part of the top plate 2 is 20mm, the distance between the bolt holes 5 is 70mm, and the distance between the two rows of bolt holes 5 is 40 mm. Three test pieces are arranged on the top plate 2 and are poured into the hollow-out part 21.
Pouring the hollow-out 21 size of the test piece: height 60mm, open end width 30mm, top width 55mm, top both sides are the fillet structure, and fretwork 21's variable cross section end length 40mm is pour to the test piece, decides cross section end length 20 mm.
Step 11: a pair of top plates 2 are symmetrically mounted on one surface of a base plate 1 through bolt holes 5 by means of bolt nuts 4.
Step 12: the first scale plate 31 of the scale plate 3 is arranged on one surface of the bottom plate 1, and two side surfaces of the first scale plate 31 are respectively matched and attached with the pair of top plates 2.
Step 13: one ends of the two steel fibers 6 are respectively embedded into the two test piece pouring hollows 21 along the 0 degree of the scale mark 8, and the embedding depth of the two steel fibers 6 is 5mm and 10 mm.
Step 14: the other end of the steel fiber 6 penetrates through a steel fiber through hole reserved in the slice 7 and is attached to the surface of the first scale plate 31, the steel fiber 6 is temporarily fixed by using forceps, and the second scale plate 32 of the scale plate 3 covers the other ends of the first scale plate 31 and the steel fiber 6.
Step 15: the scale plate 3 is fixed on the bottom plate 1 through the bolt hole 5 by the bolt and the nut 4, so that the steel fiber 6 is fixed between the first scale plate 31 and the second scale plate 32, the slice 7 is covered at the open end of the test piece pouring hollow-out 21 of the top plate 2, the inner wall of the pouring space is smeared with oil, and two test piece matrixes are poured by adopting ultra-high performance concrete in the test piece pouring hollow-out 21.
Step 16: and (5) curing the two test piece matrixes poured in the step 15 for 1 day, dismantling the scale plate 3, releasing the other end of the steel fiber 6, and completing the pulling of the steel fiber on one side out of the test piece 100.
Step 21: the steel fiber is pulled out of the test piece 100 and fixed through a test piece clamp, and a load sensor 600 is installed on the test piece clamp;
step 22: two groups of connecting pieces 300 are symmetrically arranged on two sides of the fixed section end of the steel fiber pull-out test piece 100;
step 23: the two groups of connecting pieces 300 are connected with the extensometer 400;
step 24: the extensometer 400 and the load sensor 600 are respectively connected with an acquisition system of the testing machine, the extensometer 400 is adjusted to a proper displacement loading speed, and loading and data acquisition are started;
step 25: when the steel fiber 6 is pulled out from the test piece matrix on one side, the test is stopped, the data is stored, the bonding and sliding relation curve of the steel fiber is drawn, referring to the attached drawing 8, in the drawing, the bonding and sliding relation curve of the steel fiber drawn by a straight line represents the steel fiber pulling-out test piece 100 with the burial depth of 5mm, the bonding and sliding relation curve of the steel fiber drawn by a dotted line represents the steel fiber pulling-out test piece 100 with the burial depth of 10mm, the required performance index can be extracted from the bonding and sliding relation curve of the steel fiber, and the test is completed.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The utility model provides a steel fibre pulls out test piece and pours mould, characterized by: comprises a bottom plate (1), a pair of top plates (2), a scale plate (3), a bolt and a nut (4), a bolt hole (5) and a slice (7); the bottom plate (1), the pair of top plates (2) and the scale plate (3) are respectively provided with a bolt hole (5), the pair of top plates (2) are respectively installed on one surface of the bottom plate (1) through bolt nuts (4) through the bolt holes (5), the scale plate (3) is installed on one surface of the bottom plate (1) through the bolt nuts (4) through the bolt holes (5), and the scale plate (3) is located between the pair of top plates (2); the pair of top plates (2) are respectively provided with a test piece pouring hollow (21) for pouring concrete, the test piece pouring hollows (21) on the pair of top plates (2) are oppositely arranged, and the test piece pouring hollows (21) penetrate through the top plates (2), so that the open ends of the test piece pouring hollows (21) are positioned on the contact surfaces of the top plates (2) and the scale plates (3); the scale mark (8) is arranged on the scale plate (3), and the scale mark (8) is positioned at the opening end of the test piece pouring hollow part (21); slice (7) laminating on the contact surface of scale (3) and roof (2) and can cover the open end that fretwork (21) was pour to the test piece completely, and the one end of steel fibre (6) is inserted in fretwork (21) is pour to the test piece along scale mark (8), and section (7) are run through to the other end of steel fibre (6).
2. The steel fiber extraction test piece pouring mold according to claim 1, which is characterized in that: the width of the closed end of the test piece pouring hollow part (21) is larger than that of the open end, so that one end of the poured steel fiber, which is pulled out of the test piece, forms an inverted cone-shaped variable cross-section end, and the other end of the poured steel fiber forms a fixed cross-section end.
3. The steel fiber extraction test piece pouring mold according to claim 1, which is characterized in that: scale plate (3) including first scale plate (31) and second scale plate (32), all be equipped with scale mark (8) and bolt hole (5) on first scale plate (31) and second scale plate (32), and first scale plate (31) and second scale plate (32) laminating set up and fix on bottom plate (1) through bolt nut (4) through bolt hole (5), insert between first scale plate (31) and second scale plate (32) after steel fibre (6) run through section (7).
4. The steel fiber extraction specimen casting mold according to claim 1 or 3, wherein: the scale mark (8) is composed of a plurality of nicks, the plurality of nicks are distributed in a fan shape by taking the center of an opening of the test piece pouring hollow part (21) as the center of a circle, the included angle between two adjacent nicks is 15 degrees, and the measuring range of the plurality of nicks is 0-180 degrees.
5. A specimen casting method using the steel fiber drawn specimen casting mold of claim 1, characterized by: the method comprises the following steps:
step 11: symmetrically installing a pair of top plates (2) on one surface of a bottom plate (1) through bolt and nuts (4) and bolt holes (5);
step 12: a first scale plate (31) of the scale plate (3) is arranged on one surface of the bottom plate (1), and two side surfaces of the first scale plate (31) are respectively matched and attached with the pair of top plates (2);
step 13: guiding one end of the steel fiber (6) along the scale mark (8) in an angle mode, and then embedding the steel fiber into the test piece pouring hollow (21) of the top plate (2), wherein the embedding depth of the steel fiber (6) in the test piece pouring hollow (21) is determined through measurement of a ruler;
step 14: the other end of the steel fiber (6) penetrates through a steel fiber through hole reserved in the slice (7) and is attached to the surface of the first scale plate (31), and a second scale plate (32) of the scale plate (3) is covered on the other ends of the first scale plate (31) and the steel fiber (6);
step 15: the scale plate (3) is fixed on the bottom plate (1) through a bolt hole (5) by a bolt and a nut (4), so that the cut piece (7) covers the open end of a test piece pouring hollow (21) of the top plate (2), and a test piece matrix is poured in the test piece pouring hollow (21);
step 16: maintaining the test piece matrix test piece poured in the step 15, removing the scale plate (3), releasing the other end of the steel fiber (6), and completing the drawing of the steel fiber on one side out of the test piece (100);
and step 17: inserting the other end of the steel fiber (6) into the test piece pouring hollow (21) of the other top plate (2), and pouring a test piece matrix in the test piece pouring hollow (21);
step 18: and (5) maintaining the test piece matrix test piece poured in the step (16), and removing the scale plate (3) and the top plate (2) to finish the drawing-out of the test piece (100) by the steel fibers on the two sides.
6. The method for pouring the steel fiber extraction test piece according to claim 5, which is characterized in that: in the step 15 and the step 17, before pouring, oil is applied to the inner wall of a pouring space formed by the pouring hollow part (21) and the section (7) of the test piece, and the mixture is stirred and vibrated during pouring to enable the concrete to fill the space of the pouring hollow part (21) of the test piece.
7. A method for testing the bonding slip of a test piece cast by the steel fiber pull-out test piece casting method of claim 5, which is characterized by comprising the following steps: the method comprises the following steps:
step 21: the method comprises the following steps that a steel fiber drawing test piece (100) is fixed through a test piece clamp, and a load sensor (600) is installed on the test piece clamp;
step 22: two groups of connecting pieces (300) are symmetrically arranged on two sides of the fixed section end of the steel fiber drawing test piece (100);
step 23: the two groups of connecting pieces (300) are connected with extensometers (400);
step 24: the extensometer (400) and the load sensor (600) are respectively connected with an acquisition system of the testing machine, the extensometer (400) is adjusted to a proper displacement loading speed, and the acquisition system starts loading and data acquisition;
step 25: and when the steel fiber (6) is pulled out from the test piece matrix on one side, stopping the test, storing data, drawing a bonding slip relation curve of the steel fiber, extracting required indexes, and finishing the test.
8. The method for testing adhesion slip of a steel fiber drawn test piece according to claim 7, wherein: the test piece clamp comprises a variable cross-section clamp (201) and a fixed cross-section clamp (202); the variable cross-section end of the single-side steel fiber pulling test piece is fixedly clamped through a variable cross-section clamp (201), and the fixed cross-section end of the single-side steel fiber pulling test piece is fixedly connected with a fixed cross-section clamp (202); two variable cross-section ends of the steel fiber pulling-out test piece on the two sides are fixedly clamped through a variable cross-section clamp (201).
9. The method for testing adhesion slip of a steel fiber drawn test piece according to claim 8, wherein: the variable cross-section clamp (201) is of a U-shaped structure, the opening width of the U-shaped structure is smaller than the width of the inner side of the U-shaped structure, so that the U-shaped structure can be matched and clamped with a variable cross-section end of a steel fiber pull-out test piece (100), and a load sensor (600) is installed on the variable cross-section clamp (201) through a fixing piece (500); the fixed cross-section clamp (202) is provided with a U-shaped groove (2021), a pair of clamping pieces (2022) is arranged in the U-shaped groove (2021), and a pair of locking bolts (2023) are screwed into the fixed cross-section clamp (202) and tightly prop against the pair of clamping pieces (2022) respectively, so that the pair of clamping pieces (2022) are clamped on two sides of the steel fiber (6).
10. The method for testing adhesion slip of a steel fiber drawn test piece according to claim 7, wherein: each group of connecting pieces (300) comprises two L-shaped connecting pieces which are symmetrically arranged, one end of each L-shaped connecting piece is installed at the fixed section end of the steel fiber extraction test piece (100) through the L-shaped connecting piece (502), the other end of each L-shaped connecting piece is perpendicular to the side wall of the steel fiber extraction test piece (100), the other ends of the two L-shaped connecting pieces of each group of connecting pieces (300) are parallel to each other, and the distance between the other ends of the two L-shaped connecting pieces is larger than the minimum clamping range of the extensometer (400).
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113686681A (en) * | 2021-09-06 | 2021-11-23 | 广州大学 | Drawing test device and method for fibers with different embedding angles and embedding lengths |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113686681A (en) * | 2021-09-06 | 2021-11-23 | 广州大学 | Drawing test device and method for fibers with different embedding angles and embedding lengths |
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