Two-way expansion rate testing device for reinforcement grouting material and testing method thereof

Abstract

The application discloses a bidirectional expansion rate testing device for reinforcement pouring material and a testing method thereof, which comprises a thin plate test mold, a transverse steel wire framework, a longitudinal steel wire framework and a micrometer; the space enclosed by the transverse steel wire framework and the longitudinal steel wire framework is used for pouring the concrete to be measured; the transverse steel wire framework comprises steel wires and lateral steel plates; the longitudinal steel wire framework comprises steel wires and lateral steel plates; the inner wall of the space enclosed by the transverse steel wire framework and the longitudinal steel wire framework is provided with a plastic film; the lower surface of the plastic film is adhered to the inner wall of the space enclosed by the inner and outer steel rings through transparent glue, and the upper surface of the plastic film is smeared with waterproof agent. The expansion rates in the transverse and longitudinal directions are simultaneously measured to truly reflect the expansion rate of the reinforcement pouring material for the steel pipe with an increased section, the test error caused by measuring the unidirectional expansion rate is avoided, and the measurement result is more accurate; and the testing device is simple and can be repeatedly used.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete restricted expansion rate testing technology and test method technology, and particularly relates to a bidirectional expansion rate testing device for reinforcement grouting material and a test method thereof. BACKGROUND

[0002] Concrete is the main material in engineering construction, which is prepared by cementitious material, granular aggregate, water, and additional agent and admixture added when necessary according to certain proportions, uniformly stirred, and hardened to become an artificial stone. Cement-based cementitious material will cause shrinkage deformation during the setting and hardening process due to plastic settlement shrinkage, autogenous shrinkage, chemical shrinkage, drying shrinkage, and temperature change, thereby causing shrinkage cracking of concrete and affecting the durability of concrete. The shrinkage-compensating concrete material used in industrial pools, structure reinforcement belts, and steel pipe concrete structure parts, or the self-stress and self-compacting concrete material used in pressure pipelines and grouting anchoring, has higher requirements for the expansion performance of concrete. Therefore, the accurate measurement of the expansion or shrinkage deformation of concrete material has become a research hotspot in the field of engineering research.

[0003] The "Concrete Expanding Agent" (GB23439-2009) uses the method of restricted expansion rate to characterize the expansion performance of concrete, uses the deformation of the longitudinal restrictor driven by the expansion of concrete to test the restricted expansion rate by using a micrometer. However, this method of testing expansion rate can only measure the restricted expansion rate in one direction. For the reinforcement grouting material for increasing the section of the outer steel pipe, the constraint provided by the outer steel pipe improves the strength and ductility of the core concrete. The core concrete inside the outer steel pipe is mainly stressed in two dimensions, so the ordinary test method for the expansion rate of concrete obviously cannot meet the determination of the actual expansion rate value of the reinforcement grouting material for increasing the section of the outer steel pipe. SUMMARY

[0004] In view of the above problems, the present application aims to provide a bidirectional expansion rate testing device for reinforcement grouting material and a test method thereof, i.e., an expansion deformation testing device for reinforcement grouting material for increasing the section of the outer steel pipe, which is more consistent with the constraint conditions of the reinforcement grouting material for increasing the section of the outer steel pipe, so as to improve the accuracy and reliability of the measurement of the expansion deformation of concrete in a constrained state in the actual application of the reinforcement grouting material for increasing the section of the outer steel pipe, and to improve the deficiencies of the current concrete expansion deformation testing technology.

[0005] In a first aspect, the present application provides a bidirectional expansion rate testing device for reinforcement grouting material, characterized in that it comprises a thin plate test mold, a transverse steel wire framework, a longitudinal steel wire framework, and a micrometer; the transverse steel wire framework and the longitudinal steel wire framework are placed in the thin plate test mold in a vertical state, and the space enclosed by the transverse steel wire framework and the longitudinal steel wire framework is used for pouring concrete to form a test piece to be tested; and the micrometer is used to measure the length of the test piece in the transverse and / or longitudinal directions.

[0006] As a preferred solution, the thin plate test mold comprises a bottom steel plate, front and rear lateral steel plates, left and right lateral steel plates, a plurality of screws, and a plurality of screws; the screws anchor the bottom steel plate, the front and rear lateral steel plates, and the left and right lateral steel plates from the bottom of the bottom steel plate; the front and rear lateral steel plates have two clamping grooves, and the left and right lateral steel plates are placed in the clamping grooves; the screws fix the bottom steel plate with the front and rear lateral steel plates and the left and right lateral steel plates, respectively; and the screws reinforce and fix the front and rear lateral steel plates and the left and right lateral steel plates.

[0007] The transverse steel wire framework comprises transverse steel wire framework steel plates and transverse steel wire framework steel wires connecting the two transverse steel wire framework steel plates; the intersection points of the transverse steel wire framework steel wires and the transverse steel wire framework steel plates are copper-welded with a thickness of 1mm-2mm, and the copper-welded surface is spherical, i.e., transverse steel wire framework copper-welding; and the transverse steel wire framework steel wires should be offset by 5-10mm in the vertical direction of the intersection points of the transverse steel wire framework steel plates, and the micrometer is used to measure the length change values of the two ends of the transverse steel wire framework steel wires.

[0008] The longitudinal steel wire framework comprises longitudinal steel wire framework steel plates and longitudinal steel wire framework steel wires connecting the two longitudinal steel wire framework steel plates; the space enclosed by the transverse steel wire framework and the longitudinal steel wire framework is a space enclosed by four steel plates; the intersection points of the longitudinal steel wire framework steel wires and the longitudinal steel wire framework steel plates are copper-welded with a thickness of 1mm-2 mm, and the copper-welded surface is spherical, i.e., longitudinal steel wire framework copper-welding, and the longitudinal steel wire framework steel wires should be offset by 5-10mm in the vertical direction of intersection points of the longitudinal steel wire framework steel plates, and the micrometer is used to measure the length change values of two ends of the longitudinal steel wire framework steel wires.

[0009] In a further preferred solution, the space enclosed by the transverse steel wire framework and the longitudinal steel wire framework is provided with a plurality of layers of plastic film. The lower surface of the plastic film is pasted on the inner wall of the space enclosed by the transverse steel wire framework and the longitudinal steel wire framework, and is laid in multiple layers; the waterproof agent is applied to the upper surface of the last layer of plastic film and between the multiple layers of plastic film. The lower surface of the plastic film is pasted in multiple layers by transparent glue.

[0010] The waterproof agent can be vaseline.

[0011] In a second aspect, the application provides a test method for the bidirectional expansion rate of a reinforcing grouting material, comprising the following steps:

[0012] S1: horizontally place the thin plate test mold, and respectively place the transverse steel wire framework and the longitudinal steel wire framework into the thin plate test mold;

[0013] S2: stick a plurality of layers of plastic film on the inner wall of the space surrounded by the transverse steel wire framework and the longitudinal steel wire framework, and brush waterproof agent (preferably vaseline);

[0014] S3: pour concrete between the transverse steel wire framework and the longitudinal steel wire framework, compactly vibrate, seal the upper part of the test piece with plastic film, then move into a standard curing chamber for curing, and measure the length at the specified age.

[0015] In the step S3, the test piece length measurement should meet the following requirements: 1) before measurement, adjust the zero point of the micrometer, clean the limit steel wire framework measuring head and the micrometer measuring head; the limit steel wire framework measuring head and the micrometer measuring head should be correctly contacted, and the reading should be accurate to 0.001 mm; the test samples at different ages should be measured within the specified time ± 1 h; 2) the micrometers at the two ends of the transverse and longitudinal limit steel wire frameworks should be in the same horizontal plane and on a straight line; 3) the initial value of the test sample should be measured within 1-1.2 h after demolding.

[0016] In the step S3, the test piece length measurement result should meet the following requirements: 1) the measured transverse and longitudinal limit expansion rates at the specified age should be performed according to the national standard GB23439-2017; 2) when the measured transverse and longitudinal limit expansion rates of the test sample differ by more than 15%, the test sample should be discarded; when the measured transverse and longitudinal limit expansion rates of the test sample differ by less than 15%, the average value of the transverse and longitudinal limit expansion rates should be taken as the limit expansion rate of the test sample; 3) the number of effective test samples in each group should not be less than three, the average value of the measured values of the effective test samples should be taken as the measurement result of the limit expansion rate, and the calculation result should be accurate to 0.01%.

[0017] The technical principle and research process of the application are as follows:

[0018] This invention reveals that in practical steel tube cross-section enlargement reinforcement methods, the internal core concrete material (grouting material) often exhibits problems such as incomplete compaction or gaps between the steel tubes. This weakens the compressive force between the concrete and the steel tube, hindering the full utilization of the concrete's primary two-dimensional compressive strength and ultimately creating potential engineering hazards. Existing methods for testing the expansion rate of ordinary concrete (unidirectional expansion rate) are clearly insufficient for determining the actual expansion rate of the grouting material used in steel tube cross-section enlargement reinforcement. The test results do not accurately reflect the true expansion rate of the grouting material. Therefore, a new testing device is needed to accurately reflect the actual expansion rate of the concrete used in steel tube cross-section enlargement reinforcement, providing a theoretical foundation for structural design. This invention introduces the concept of bidirectional expansion rate for the first time, distinguishing it from the unidirectional expansion rate in existing technologies. The experimental device designed in this invention accurately reflects the actual expansion rate of the grouting material used in steel tube cross-section enlargement reinforcement; and the results of unidirectional and bidirectional expansion rate tests are compared and verified through experiments.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] This invention provides a novel testing device and method for bidirectional expansion rate, which better reflects the actual constraints of grouting materials used for reinforcing enlarged cross-sections of outer steel pipes. It is simple in construction, easy to operate, and yields highly accurate results. The main purpose of the device is to better reflect the actual stress state of the grouting material compared to traditional unidirectional expansion rate constraints, resulting in more accurate test results that can be used for verification (the difference between bidirectional and unidirectional expansion rates). The concept of bidirectional expansion rate is introduced for the first time. Attached Figure Description

[0021] Figure 1 This is a front view of the thin plate test mold of the device of the present invention.

[0022] Figure 2 This is a top view of the thin plate test mold of the device of the present invention.

[0023] Figure 3 This is a side view of the thin plate test mold of the device of the present invention.

[0024] Figure 4 This is a front view of the transverse steel wire skeleton of the device of the present invention.

[0025] Figure 5 This is a side view of the transverse steel wire skeleton of the device of the present invention.

[0026] Figure 6 This is a front view of the longitudinal steel wire skeleton of the device of the present invention.

[0027] Figure 7This is a side view of the longitudinal steel wire skeleton of the device of the present invention.

[0028] Figure 8 This is a three-dimensional structural diagram of the device of the present invention.

[0029] In the diagram: 1. Screw; 2. Bottom steel plate; 3. Front and rear side steel plates; 4. Left and right side steel plates; 5. Screw; 6. Horizontal steel wire skeleton wire; 7. Horizontal steel wire skeleton steel plate; 8. Horizontal steel wire skeleton brazing; 9. Longitudinal steel wire skeleton wire; 10. Longitudinal steel wire skeleton steel plate; 11. Longitudinal steel wire skeleton brazing. Detailed Implementation

[0030] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example 1

[0032] like Figures 1-8 As shown, a bidirectional expansion rate testing device for grouting material used for reinforcing steel pipes with enlarged cross-sections includes a screw 1; a bottom steel plate 2; lateral steel plates 3 on the front and rear sides; lateral steel plates 4 on the left and right sides; a screw 5; a transverse steel wire skeleton 6; a transverse steel wire skeleton plate 7; a transverse steel wire skeleton brazing 8; a longitudinal steel wire skeleton 9; a longitudinal steel wire skeleton plate 10; and a longitudinal steel wire skeleton brazing 11.

[0033] In this embodiment, the lateral steel plates (the front and rear lateral steel plates 3 and the left and right lateral steel plates 4) are fixed to the bottom steel plate 2 by screws 5. To facilitate demolding and improve service life, the screws 5 are tightened from bottom to top starting from the bottom steel plate 2, and the length of the screws 5 does not exceed 2 / 3 of the lateral steel plate. The screw rod 1 fixes the upper and lower lateral steel plates. To facilitate accurate measurement of the wire elongation value by a dial indicator, in the transverse and longitudinal restricting wire skeleton, the surface of the joint between the wire (transverse wire skeleton wire 6 or longitudinal wire skeleton wire 9) and the steel plate (transverse wire skeleton steel plate 7 or longitudinal wire skeleton steel plate 10) is brazed with a thickness of 1mm to 2mm (unit of each component size: mm), and it is made into a spherical surface (transverse wire skeleton brazing 8 or longitudinal wire skeleton brazing 11). To reduce the influence of friction on the injection material during expansion, a plastic film is provided on the inner wall of the space enclosed by the transverse and longitudinal wire skeletons. The plastic film consists of a polyethylene film with a thickness of approximately 0.02 mm and a Teflon film with a thickness of 0.3 mm. The polyethylene film is adhered to the sides and bottom of the cavity formed by the four steel skeleton plates using transparent adhesive. After adhesion, a layer of petroleum jelly is applied. Then, three layers of Teflon film are applied to the five surfaces of the cavity, with a layer of petroleum jelly applied between each layer. A layer of petroleum jelly is also applied to the top surface of the last Teflon film layer. After demolding, the initial values ​​of the specimen should be measured within 1 hour, followed by the corresponding elongation values ​​of the specimen at the appropriate age.

[0034] The above-mentioned test method for the bidirectional expansion rate of the grouting material used for reinforcing the enlarged cross-section of the outer steel pipe includes the following steps:

[0035] S1: Place the thin plate mold horizontally, and place the transverse steel wire skeleton and the longitudinal steel wire skeleton into the thin plate mold respectively;

[0036] S2: Adhere a plastic film to the inner wall of the space enclosed by the horizontal and vertical steel wire skeletons, and apply a waterproofing agent (Vaseline).

[0037] S3: Pour concrete between the transverse and longitudinal steel wire skeletons, vibrate to compact, seal the top of the specimen with plastic film, and then move it into the standard curing room for curing. Measure the length at the specified age.

[0038] The specimen length measurement shall comply with the following provisions: 1) Before measurement, the dial indicator shall be zeroed, and the limiting wire skeleton probe and the dial indicator probe shall be cleaned. The limiting wire skeleton probe and the dial indicator probe shall be in correct contact, and the reading shall be accurate to 0.001 mm. Specimens of different ages shall be measured within ±1 hour of the specified time; 2) The dial indicators at both ends of the transverse and longitudinal limiting wire skeleton probes shall be in the same horizontal plane and shall be in a straight line; 3) The initial value of the specimen shall be measured within 1-1.2 hours after demolding.

[0039] The specimen length measurement results shall comply with the following provisions: 1) The transverse and longitudinal restricted expansion rates at the measured age shall be in accordance with the national standard GB23439-2017; 2) If the difference between the transverse and longitudinal restricted expansion rates of the specimen exceeds 15%, it shall be discarded; if the difference between the transverse and longitudinal restricted expansion rates of the specimen is less than 15%, the average value of the transverse and longitudinal restricted expansion rates shall be taken as the restricted expansion rate of the specimen; 3) Each group of valid specimens shall not be less than three, and the average value of the measured values ​​of the valid specimens shall be taken as the measurement result of the restricted expansion rate. The calculation result shall be accurate to 0.01%.

[0040] Example 2

[0041] In Example 1, the surface of the joint between the steel wire (transverse steel wire skeleton 6 or longitudinal steel wire skeleton 9) and the steel plate (transverse steel wire skeleton plate 7 or longitudinal steel wire skeleton plate 10) is welded with iron (transverse steel wire skeleton copper weld 8 or longitudinal steel wire skeleton copper weld 11) to a thickness of 1mm to 2mm and made into a spherical surface. The remaining test methods and test requirements are consistent with those in Example 1.

[0042] Example 3

[0043] The polyethylene plastic film with a thickness of approximately 0.02 mm in Example 1 was removed, and the remaining test methods and requirements remained the same as in Example 1.

[0044] Example 4

[0045] The Teflon film with a thickness of approximately 0.3 mm in Example 1 was removed, and the remaining test methods and requirements remained the same as in Example 1.

[0046] Comparative Example 1

[0047] The transverse steel wire skeleton in the structure of Example 1 is removed, and only the longitudinal steel wire skeleton is retained. The remaining test methods and test requirements are consistent with those of Example 1.

[0048] Comparative Example 2

[0049] The longitudinal steel wire skeleton in the structure of Example 1 was removed, and only the transverse steel wire skeleton was retained. The remaining test methods and test requirements were the same as those in Example 1.

[0050] Comparative Example 3

[0051] Remove the transverse and longitudinal steel wire skeletons from the structure in Example 1, and attach transverse and longitudinal strain gauges to the side steel plates. The remaining test methods and experimental requirements are consistent with those in Example 1.

[0052] Table 1 Test results of unidirectional and bidirectional expansion rates

[0053]

[0054] The above experiment aims to compare and analyze the test results of unidirectional expansion rate with those of bidirectional expansion rate. By increasing the comparative sample of unidirectional expansion rate, it can be confirmed that the present invention improves the accuracy and reliability of measuring the expansion deformation of concrete under constraint in the actual application of the grouting material for reinforcing the enlarged cross-section of the outer steel pipe.

Claims

1. A bidirectional expansion rate testing device for reinforcing grouting materials, characterized in that: This includes thin plate test molds, transverse steel wire skeletons, longitudinal steel wire skeletons, and dial indicators; The transverse and longitudinal steel wire skeletons are placed vertically inside the thin plate mold, and the space enclosed by the transverse and longitudinal steel wire skeletons is used to pour concrete to form the specimen to be tested. The dial indicator is used to measure the specimen's transverse and / or longitudinal length; The thin plate test mold includes a bottom steel plate (2), front and rear side steel plates (3), left and right side steel plates (4), several screws (1) and several bolts (5). The screw (5) anchors the bottom steel plate (2), the front and rear side steel plates (3) and the left and right side steel plates (4) from below the bottom steel plate (2); There are two slots on the front and rear side steel plates (3): the two ends of the left and right side steel plates (4) are placed in the slots; screws (5) fix the bottom steel plate (2) to the front and rear side steel plates (3) and the left and right side steel plates (4) respectively. The screw (1) reinforces and fixes the lateral steel plates (3) on the front and rear sides and the lateral steel plates (4) on the left and right sides; The transverse steel wire skeleton includes a transverse steel wire skeleton plate (7) and a transverse steel wire (6) that connects the two transverse steel wire skeleton plates (7). The surface of the intersection point of the transverse steel wire (6) and the transverse steel wire skeleton plate (7) is brazed with copper for 1 mm to 2 mm thickness, and the copper is brazed into a spherical surface, i.e., transverse steel wire skeleton copper brazing (8). The transverse steel wire (6) should be offset by 5 to 10 mm in the vertical direction of the intersection point of the transverse and longitudinal central axes of the transverse steel wire skeleton plate (7). A dial indicator is used to measure the length change value of the two ends of the transverse steel wire skeleton (6). The longitudinal wire skeleton includes a longitudinal wire skeleton steel plate (10) and a longitudinal wire skeleton steel wire (9) that connects two longitudinal wire skeleton steel plates (10); the space enclosed by the transverse wire skeleton and the longitudinal wire skeleton is the space enclosed between four steel plates; the surface of the intersection of the longitudinal wire skeleton steel wire (9) and the longitudinal wire skeleton steel plate (10) is brazed with copper for 1mm~2mm thickness, and the copper is brazed into a spherical surface, i.e., longitudinal wire skeleton copper brazing (11), and the longitudinal wire skeleton steel wire (9) should be offset by 5~10mm in the vertical direction along the intersection of the transverse and longitudinal central axes of the longitudinal wire skeleton steel plate (10). A dial indicator is used to measure the length change value of the ends of the longitudinal wire skeleton steel wire (9) on both sides.

2. The bidirectional expansion rate testing device for reinforcing grouting materials according to claim 1, characterized in that: The inner wall of the space enclosed by the transverse and longitudinal steel wire skeletons is provided with multiple layers of plastic film.

3. The bidirectional expansion rate testing device for reinforcing grouting materials according to claim 2, characterized in that: The lower surface of the plastic film is adhered to the inner wall of the space enclosed by the horizontal and vertical steel wire skeletons, and multiple layers are laid; a waterproofing agent is applied between the multiple layers of plastic film and on the upper surface of the last layer of plastic film.

4. The bidirectional expansion rate testing device for reinforcing grouting materials according to claim 3, characterized in that: The lower surface of the plastic film is bonded in multiple layers with transparent adhesive; the waterproofing agent is petroleum jelly.

5. A test method for the bidirectional expansion rate of a reinforcing grouting material, characterized in that: The application of the testing apparatus as described in any one of claims 1 to 4 includes the following steps: S1: Place the thin plate mold horizontally, and place the transverse steel wire skeleton and the longitudinal steel wire skeleton into the thin plate mold respectively; S2: Adhere multiple layers of plastic film to the inner wall of the space enclosed by the horizontal and vertical steel wire skeletons, and apply waterproofing agent. S3: Pour concrete between the transverse and longitudinal steel wire skeletons, vibrate to compact, seal the top of the specimen with plastic film, and then move it into the standard curing room for curing. Measure the length at the specified age.

6. The test method for the bidirectional expansion rate of the reinforcing grouting material according to claim 5, characterized in that: In step S3, the specimen length measurement should meet the following requirements: 1) Before measurement, the dial indicator should be zeroed, and the limiting wire skeleton probe and the dial indicator probe should be cleaned; the limiting wire skeleton probe and the dial indicator probe should be in correct contact, and the reading should be accurate to 0.001 mm; specimens of different ages should be measured within ±1 hour of the specified time; 2) The dial indicators at both ends of the transverse and longitudinal limiting wire skeleton probes should be in the same horizontal plane and should be on a straight line; 3) The initial value of the specimen should be measured within 1-1.2 hours after the specimen is demolded.

7. The test method for the bidirectional expansion rate of the reinforcing grouting material according to claim 6, characterized in that: In step S3, the specimen length measurement results should meet the following requirements: 1) The transverse and longitudinal restricted expansion rates at the measured age should be performed in accordance with the national standard GB23439-2017; 2) If the difference between the transverse and longitudinal restricted expansion rates of the specimen exceeds 15%, it should be discarded; if the difference between the transverse and longitudinal restricted expansion rates of the specimen is less than 15%, the average value of the transverse and longitudinal restricted expansion rates should be taken as the restricted expansion rate of the specimen; 3) Each group of valid specimens should have no fewer than three, and the average value of the measured values ​​of the valid specimens should be taken as the measurement result of the restricted expansion rate. The calculation result should be accurate to 0.01%.

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