Embedded bar type concrete test block capable of realizing direct tensile test

Abstract

The invention discloses a bar planting type concrete test block capable of realizing a direct tensile test. The bar planting type concrete test block comprises a concrete pouring block bar planting structure, the concrete pouring block comprises a damage area in the middle and stretching areas at the two ends, and the whole concrete pouring block is in the form that the two ends are large and the middle is small. The embedded steel bar structure comprises main steel bars and auxiliary steel bars, the ends, located in the concrete pouring block, of the main steel bars are embedded sections, and the auxiliary steel bars are evenly welded to the side walls of the embedded sections of the main steel bars in the circumferential direction. According to the embedded steel bar type concrete test block capable of achieving the direct tensile test, the embedded steel bar structure is placed in the test block mold, the embedded steel bar type concrete test block is obtained through concrete pouring, the tensile strength of the embedded steel bar type concrete test block is tested in a direct tensile mode, errors caused by an indirect method are avoided, and the tensile strength of the embedded steel bar type concrete test block is improved. The measured tensile strength can truly reflect the mechanical property of the concrete in an actual tensile state, and the accuracy of the tensile strength test of the concrete is improved.

Description

Technical Field

[0001] The invention relates to the technical field of building engineering material testing, in particular to a rebar-embedded concrete test block capable of realizing a direct tensile test. Background Art

[0002] As the core material of engineering structures such as buildings, bridges, and tunnels, the mechanical properties of concrete directly affect the safety and durability of the structure. In the test of concrete mechanical properties, the compressive strength can be directly measured by methods such as cube compression test and axial compression test, which conforms to the provisions of GB / T 50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". However, the tensile strength of concrete is only about 1 / 10 of the compressive strength. When conventional concrete test blocks are used for tensile tests, the tensile strength of concrete cannot be accurately measured due to the local damage of concrete in the fixture area. In the current standards, the tensile strength of concrete is usually obtained by indirect test methods such as splitting test and bending test. However, these indirect methods cannot truly reflect the mechanical behavior of concrete under actual tension. Therefore, it is necessary to design a concrete test block that can realize direct tensile test in order to obtain more accurate tensile strength and stress-strain curve. Summary of the invention

[0003] The present application proposes a rebar-embedded concrete test block capable of realizing direct tensile testing, which overcomes the problem of local damage of traditional test blocks in direct tensile testing, so that the tensile strength and constitutive curve of concrete can be accurately obtained through direct tensile testing.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: a reinforced concrete test block capable of realizing direct tensile test, comprising a concrete casting block reinforced concrete structure; The concrete casting block comprises a destruction zone in the middle and stretching zones at both ends, and the concrete casting block is generally in a shape of being large at both ends and small in the middle; The embedded reinforcement structure includes main reinforcement and auxiliary reinforcement. The main reinforcement is located at one end of the concrete casting block as an embedded section, and the auxiliary reinforcement is evenly welded to the side wall of the embedded section of the main reinforcement in the circumferential direction.

[0005] Furthermore, the overall dimensions of the embedded reinforced concrete test block formed by the concrete casting block and the embedded reinforced structure are 600 mm in length, 120 mm in width, and 70 mm in thickness.

[0006] Furthermore, the width of the failure zone in the middle of the concrete casting block is 50 mm.

[0007] Furthermore, the main reinforcement is made of HRB400 grade steel bars with a diameter of 22 mm and a length of 200 mm, of which 100 mm is embedded in the concrete casting block to form an embedded section and 100 mm is exposed to form an exposed section; there are four auxiliary bars, which are evenly distributed along the circumference of the main bars. The auxiliary bars are made of HRB400 grade steel bars with a diameter of 16 mm. The center axes of the two auxiliary bars on the same side are 40 mm apart, and the center axis of the auxiliary bar close to the end of the main bar is 30 mm away from the end of the main bar.

[0008] Furthermore, it also includes a test block mold, the inner wall shape of the test block mold is the same as the concrete casting block, and rebar embedding holes are opened in the centers of both ends of the test block mold, and the inner diameter of the rebar embedding holes is the same as the diameter of the main reinforcement.

[0009] Further, the production process of the embedded concrete test block includes the following steps: Step 1: Test block mold processing: According to the design size, make the corresponding test block mold. The inside of the test block mold adopts a high-precision steel template, and a release agent is applied on the surface of the test block mold to ensure that the surface of the concrete casting block is smooth and defect-free after demoulding; Step 2: Processing and positioning of embedded reinforcement: Use HRB400 grade steel bars with a diameter of 22 mm as the main reinforcement, weld 4 auxiliary reinforcements with a diameter of 16 mm, and evenly distribute the auxiliary reinforcements around the main reinforcements. The main reinforcements and auxiliary reinforcements are combined to form an embedded reinforcement structure; accurately position the processed embedded reinforcement structure in the test block mold according to the design size, embed two embedded reinforcement structures in each concrete casting block, and place the two embedded reinforcement structures at the two top ends of the test block mold before pouring. The main reinforcement of the embedded reinforcement structure passes through the embedded reinforcement through hole of the test block mold, and the embedded section of the main reinforcement is located in the test block mold; Step 3: Concrete pouring: After arranging the reinforcement structure in the test block mold, mix the concrete according to the designed proportion; then pour the mixed concrete evenly into the test block mold, and use a vibrating table or vibrating rod to compact the concrete in the test block mold; Step 4: Curing and demoulding: After pouring, the embedded concrete test block is cured under standard environmental conditions for 28 days; after curing, the embedded concrete test block is demoulded from the test block mold; Step 5. Tensile test: Fix the rebar structure of the rebar-embedded concrete test block on the tensile testing machine, slowly apply tension, record the maximum tension when the concrete of the concrete casting block is destroyed through the test instrument, and obtain the tensile strength of the concrete, collect the stress and strain data during the loading process, draw the constitutive relationship curve of the concrete, and obtain the mechanical properties of the concrete under direct tension.

[0010] The present invention has the following beneficial effects: 1. The present application provides a rebar-embedded concrete test block capable of realizing direct tensile test. The rebar-embedded concrete test block of the present application is obtained by placing a rebar structure in a test block mold and pouring concrete. The tensile strength of the rebar-embedded concrete test block is tested by direct tensile method, thereby avoiding the errors caused by indirect methods (such as splitting test and bending test), so that the measured tensile strength can truly reflect the mechanical properties of concrete under actual tensile state, thereby improving the accuracy of concrete tensile strength test.

[0011] 2. The present application provides a rebar-embedded concrete test block that can realize direct tensile test. The concrete casting block is designed to be large at both ends and small in the middle, with a concrete width of 50 mm in the middle, to ensure that tensile failure starts from this area, avoid the influence of local failure at the fixture end, and ensure the accuracy and consistency of the test data. In addition, by welding 4 auxiliary bars to the embedded section of the main bar, the internal force between the main bar and the concrete is greatly enhanced, effectively avoiding the risk of main bar slippage during the test, ensuring uniform transmission of tension and stable and reliable test results.

[0012] 3. The present application provides a rebar-embedded concrete test block capable of realizing direct tensile testing. The block has a simple structure and a standardized manufacturing process, and is suitable for concrete strength testing of different specifications. At the same time, since the rebar-embedded process and mold manufacturing are relatively simple, the block is suitable for large-scale promotion and application in construction projects and laboratory testing. Compared with the traditional complex fixture design, the present application only requires ordinary rebar-embedded and concrete pouring to realize the test block manufacturing, which reduces the preparation work before the test, reduces the complexity of the test operation and reduces the material cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings, which constitute a part of the specification, illustrate embodiments disclosed in the present application and, together with the description, serve to explain the principles disclosed in the present application.

[0014] The present disclosure may be more clearly understood from the following detailed description with reference to the accompanying drawings, in which: Figure 1 This is a schematic diagram of the structure of the reinforced concrete test block in this application; Figure 2 This is the main view of the embedded reinforced concrete test block of this application; Figure 3 This is a side view of the reinforced concrete test block of this application; Figure 4 This is a schematic diagram of the test block mold structure for this application; Figure 5 This is a schematic diagram of the test block mold and the reinforcing bar structure location for this application; Figure 6 This is a schematic diagram of the concrete casting block and the reinforcing bar structure formed in the test block mold for this application; Figure 7 The size of the concrete casting block produced in the embodiment of this application is shown in FIG. Figure 1 ; Figure 8 The size of the concrete casting block produced in the embodiment of this application is shown in FIG. Figure 2 ; Fig. 9 The dimensions of the reinforcing bar structure produced in the embodiment of this application are shown in FIG. Figure 1 ; Fig.10 The dimensions of the reinforcing bar structure produced in the embodiment of this application are shown in FIG. Figure 2 .

[0015] In the figure: 1. concrete casting block; 101. damage zone; 102. stretching zone; 2. embedded reinforcement structure; 201. main reinforcement; 202. auxiliary reinforcement; 3. test block mold; 301. embedded reinforcement through hole. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0017] Please see attached Figure 1 , Attachment Figure 2 , Attachment Figure 3 As shown, a rebar-embedded concrete test block capable of realizing direct tensile test comprises a concrete casting block 1 and a rebar-embedded structure 2; The concrete casting block 1 comprises a destruction zone 101 in the middle and stretching zones 102 at both ends. The concrete casting block 1 is generally large at both ends and small in the middle. The embedded reinforcement structure 2 includes a main reinforcement 201 and an auxiliary reinforcement 202. One end of the main reinforcement 201 located inside the concrete casting block 1 is an embedded section, and the auxiliary reinforcement 202 is uniformly welded to the side wall of the embedded section of the main reinforcement 201 in a circumferential direction.

[0018] Please see attached Figure 4 , Attachment Figure 5 and attached Figure 6 As shown, a rebar-embedded concrete test block capable of realizing direct tensile test also includes a test block mold 3, the inner wall shape of the test block mold 3 is the same as that of the concrete casting block 1, and rebar-embedded through holes 301 are opened at the centers of both ends of the test block mold 3, and the inner diameter of the rebar-embedded through holes 301 is the same as the diameter of the main reinforcement 201.

[0019] Please see attached Figures 1 to 6 And attached Figure 7 , Attachment Figure 8 , attached Fig. 9 , Attachment Fig.10 A reinforced concrete test block capable of realizing direct tensile test, the reinforced concrete test block has an overall size of 600 mm in length, 120 mm in width and 70 mm in thickness, and is composed of a concrete casting block 1 and a reinforcing bar structure 2. The concrete casting block 1 includes a destruction zone 101 in the middle and tensile zones 102 at both ends. The concrete casting block 1 is generally large at both ends and small in the middle. The width of the destruction zone 101 in the middle of the concrete casting block 1 is 50 mm, so as to ensure that the destruction starts from this area in the tensile test and achieve a uniform stress effect.

[0020] The embedded reinforcement structure 2 includes a main reinforcement 201 and an auxiliary reinforcement 202. The end of the main reinforcement 201 located inside the concrete casting block 1 is an embedded section. The main reinforcement 201 is made of HRB400 grade steel bars with a diameter of 22 mm and a length of 200 mm, of which 100 mm is embedded in the concrete casting block 1 to form an embedded section, and 100 mm is exposed to form an exposed section. In order to enhance the bond strength between the embedded reinforcement structure 2 and the concrete casting block 1, four auxiliary reinforcements 202 are welded on the side wall of the embedded section of the main reinforcement 201 located inside the concrete casting block 1. The auxiliary reinforcement 202 is made of HRB400 grade steel bars with a diameter of 16 mm. The auxiliary reinforcement 202 is evenly distributed along the circumference of the main reinforcement 201, and the center axes of the two auxiliary reinforcements 202 on the same side are 40 mm apart. The center axis of the auxiliary reinforcement 202 close to the end of the main reinforcement 201 is 30 mm away from the end of the main reinforcement 201, so as to significantly improve the bond strength between the embedded reinforcement and concrete and ensure the uniform transfer of load during the tensile test.

[0021] The present application proposes a production process of a reinforced concrete test block capable of realizing a direct tensile test, comprising the following steps: Step 1, test block mold processing: according to the design size, make the corresponding test block mold 3, the inner wall shape of the test block mold 3 is the same as the concrete casting block 1, and the two ends of the test block mold 3 are provided with anchoring holes 301. The inner diameter of the anchoring holes 301 is the same as the diameter of the main reinforcement 201. The inside of the test block mold 3 adopts a high-precision steel template, and the surface of the test block mold 3 is coated with a release agent to ensure that the surface of the concrete casting block 1 is smooth and defect-free after demoulding.

[0022] Step 2, processing and positioning of embedded reinforcement: Use HRB400 grade steel bars with a diameter of 22 mm as the main reinforcement 201, weld 4 auxiliary reinforcements 202 with a diameter of 16 mm, ensure that the auxiliary reinforcements 202 are evenly distributed around the main reinforcement 201, and the main reinforcement 201 and the auxiliary reinforcement 202 are combined to form an embedded reinforcement structure 2. The processed embedded reinforcement structure 2 is accurately positioned in the test block mold 3 according to the design size. Two embedded reinforcement structures 2 are embedded in each concrete casting block 1. The two embedded reinforcement structures 2 are respectively placed at the two top ends of the test block mold 3 before casting, and the main reinforcement 201 of the embedded reinforcement structure 2 passes through the embedded reinforcement through hole 301 of the test block mold 3. Make sure that the embedded section of the main reinforcement 201 in the embedded reinforcement concrete test block of this application obtained after casting is accurately embedded 100 mm into the concrete casting block 1, and ensure that the exposed part is located at the top of the concrete casting block 1.

[0023] Step 3: Concrete pouring: After arranging the embedded reinforcement structure 2 in the test block mold 3, the concrete is mixed according to the designed ratio to ensure the uniformity and workability of the concrete mixture. Then the mixed concrete is evenly poured into the test block mold 3, and the concrete in the test block mold 3 is compacted using a vibrating table or a vibrating rod to reduce bubbles in the concrete and avoid voids affecting the strength of the embedded reinforcement concrete test block of this application.

[0024] Step 4, curing and demoulding: After pouring, the embedded concrete test block should be cured under standard environmental conditions for 28 days to ensure the full development of concrete strength. After curing, the embedded concrete test block is demoulded from the test block mold 3 to avoid damaging the test block corners and ensure the shape of the embedded concrete test block is intact.

[0025] Step 5, tensile test: fix the rebar structure 2 of the rebar-embedded concrete test block on the tensile test machine, slowly apply tension, record the maximum tension when the concrete of the concrete casting block 1 is destroyed by the test instrument, and obtain the tensile strength of the concrete. By collecting stress and strain data during the loading process, draw the constitutive relationship curve of concrete to accurately reflect the mechanical properties of concrete under direct tension.

[0026] Compared with the prior art, the present invention has the following advantages: Realize direct tensile test: Use direct tensile method to test the tensile strength of concrete, avoiding the errors caused by indirect methods (such as splitting test and bending test), so that the measured tensile strength can truly reflect the mechanical properties of concrete under actual tensile state.

[0027] Reasonable structural design: The concrete test block of the present invention is designed to be large at both ends and small in the middle, and the width of the concrete in the middle is 50 mm, ensuring that the tensile failure starts from this area, avoiding the influence of local failure at the fixture end, and ensuring the accuracy and consistency of the test data.

[0028] Improve the bonding strength of the embedded reinforcement: By welding 4 auxiliary reinforcements to the embedded section of the main reinforcement, the internal bonding force between the main reinforcement and the concrete is greatly enhanced, effectively avoiding the risk of main reinforcement slippage during the test, ensuring uniform transmission of tension, and stable and reliable test results.

[0029] High-precision loading control: The designed embedded reinforcement part has high strength and rigidity, which can provide precise loading control in the tensile test, avoiding the problem of local stress concentration caused by uneven loading in traditional test blocks, and making the concrete test block evenly stressed during the entire test process.

[0030] Strong adaptability and suitable for promotion and application: The test block of the present invention has a simple design structure and a standardized production process, and is suitable for concrete strength tests of different specifications. At the same time, since the rebar embedding process and mold production are relatively simple, it is suitable for large-scale promotion and application in construction projects and laboratory tests.

[0031] Convenient for studying the constitutive relationship of concrete components: Through the test block of the present invention, the stress-strain curve can be recorded in real time during the loading process, and the complete constitutive relationship of concrete under direct tension can be obtained, which provides important experimental data for the establishment and analysis of the mechanical model of concrete materials.

[0032] Strong test repeatability: Since the structural design of the present invention ensures the uniformity of the force on the concrete during the test and reduces the errors caused by local damage or changes in the test block morphology, it shows high repeatability in the tests of different batches of test blocks, with good data consistency, which is convenient for comparative analysis.

[0033] Low test block processing and testing costs: Compared with the traditional complex fixture design, the present invention can realize test block production only through ordinary rebar planting and concrete pouring, which reduces the preparation work before the test and reduces the complexity of test operation and material cost.

[0034] Enhance the accuracy of structural component design basis: By obtaining accurate tensile strength and stress-strain relationship data, it can provide more reliable tensile strength parameters for concrete structure designers, which helps to optimize structural design and improve the safety and durability of components.

[0035] Eliminate the reliance on complex fixtures: Traditional tensile tests require the use of special fixtures, which are complex to operate and require high installation precision. In the design of the embedded steel bar test block of the present invention, the exposed section of the main steel bar is directly used for fixing, which simplifies the test process, reduces equipment reliance, and improves test efficiency.

Claims

1. A reinforced concrete test block capable of realizing direct tensile test, characterized in that: It comprises a concrete casting block (1) and a reinforcing bar structure (2); The concrete casting block (1) comprises a destruction zone (101) in the middle and stretching zones (102) at both ends. The concrete casting block (1) is generally large at both ends and small in the middle. The embedded reinforcement structure (2) comprises a main reinforcement (201) and auxiliary reinforcement (202); one end of the main reinforcement (201) located inside the concrete casting block (1) is an embedded section; and the auxiliary reinforcement (202) is uniformly welded to the side wall of the embedded section of the main reinforcement (201) in the circumferential direction.

2. The embedded steel bar concrete test block capable of realizing direct tensile test according to claim 1 is characterized in that: The overall dimensions of the embedded reinforcement concrete test block formed by the concrete casting block (1) and the embedded reinforcement structure (2) are 600 mm in length, 120 mm in width and 70 mm in thickness.

3. The embedded steel bar concrete test block capable of realizing direct tensile test according to claim 2, characterized in that: The width of the failure zone (101) in the middle of the concrete casting block (1) is 50 mm.

4. The embedded steel bar concrete test block capable of realizing direct tensile test according to claim 3 is characterized in that: The main reinforcement (201) is made of HRB400 grade steel bars with a diameter of 22 mm and a length of 200 mm, of which 100 mm is embedded in the concrete casting block (1) to form an embedded section and 100 mm is exposed to form an exposed section. There are four auxiliary reinforcements (202), and the auxiliary reinforcements (202) are evenly distributed along the circumference of the main reinforcement (201). The auxiliary reinforcements (202) are made of HRB400 grade steel bars with a diameter of 16 mm. The center axes of the two auxiliary reinforcements (202) on the same side are 40 mm apart, and the center axis of the auxiliary reinforcement (202) close to the end of the main reinforcement (201) is 30 mm away from the end of the main reinforcement (201).

5. The embedded steel bar concrete test block capable of realizing direct tensile test according to claim 4 is characterized in that: It also includes a test block mold (3), the inner wall shape of the test block mold (3) is the same as that of the concrete casting block (1), and reinforcing bar through holes (301) are opened at the centers of both ends of the test block mold (3), and the inner diameter of the reinforcing bar through holes (301) is the same as the diameter of the main reinforcing bar (201).

6. The embedded steel bar concrete test block capable of realizing direct tensile test according to claim 5, characterized in that: The production process of the embedded concrete test block includes the following steps: Step 1: Processing the test block mold: according to the design size, a corresponding test block mold (3) is manufactured. A high-precision steel template is used inside the test block mold (3), and a release agent is coated on the surface of the test block mold (3) to ensure that the surface of the concrete casting block (1) is smooth and free of defects after demoulding; Step 2, processing and positioning of embedded reinforcement: using HRB400 grade steel bars with a diameter of 22 mm as main reinforcement (201), welding 4 auxiliary reinforcements (202) with a diameter of 16 mm, the auxiliary reinforcements (202) are evenly distributed around the main reinforcement (201), and the main reinforcement (201) and the auxiliary reinforcement (202) are combined to form an embedded reinforcement structure (2); the processed embedded reinforcement structure (2) is accurately positioned in the test block mold (3) according to the design size, and two embedded reinforcement structures (2) are embedded in each concrete casting block (1). The two embedded reinforcement structures (2) are respectively placed at the two top ends of the test block mold (3) before casting, and the main reinforcement (201) of the embedded reinforcement structure (2) passes through the embedded reinforcement through hole (301) of the test block mold (3), and the embedded section of the main reinforcement (201) is located in the test block mold (3); Step 3, concrete pouring: after arranging the reinforcing bar structure (2) in the test block mold (3), the concrete is mixed according to the designed proportion; then the mixed concrete is evenly poured into the test block mold (3), and the concrete in the test block mold (3) is compacted using a vibration table or a vibration rod; Step 4, curing and demoulding: After pouring, the embedded steel bar concrete test block is cured under standard environmental conditions for 28 days; after curing, the embedded steel bar concrete test block is demoulded from the test block mold (3); Step 5, tensile test: fix the embedded reinforcement structure (2) of the embedded reinforcement concrete test block on the tensile testing machine, slowly apply tensile force, record the maximum tensile force when the concrete of the concrete casting block (1) is destroyed by the test instrument, and obtain the tensile strength of the concrete, collect the stress and strain data during the loading process, draw the constitutive relationship curve of the concrete, and obtain the mechanical properties of the concrete under direct tension.

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