Testing device and method for analyzing influence of internal relative humidity on concrete shrinkage by adjusting external humidity field

Abstract

The invention discloses a test device and method for analyzing the influence of internal relative humidity on concrete shrinkage by adjusting an external humidity field, and relates to the technical field of concrete tests.The test device comprises a shrinkage mold assembly and a supporting base assembly, and the supporting base assembly comprises multiple sets of semicircular-arc-shaped steel rings and balls which are arranged and connected in parallel; an embedded type strain sensor and an embedded type humidity sensor are arranged in the shrinkage mold assembly, and the output end of the embedded type strain sensor and the output end of the embedded type humidity sensor are connected with a controller through lines. According to the method, the thin-wall arc-shaped shrinkage test piece can be conveniently prepared, and a uniform and controllable external humidity field is established around the shrinkage test piece, so that the effective effect of external humidity on the shrinkage test piece is guaranteed, the quantitative regulation and control of the relative humidity gradient rate in the test piece are further realized, and the theoretical research requirement of concrete shrinkage is met.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete testing, and in particular to an experimental device and method for analyzing the influence of internal relative humidity on concrete shrinkage by adjusting the external humidity field. Background Art

[0002] Concrete shrinkage can cause the initiation and development of microcracks inside the matrix, deteriorating the mechanical properties and durability of the material. Therefore, its development law and evolution mechanism have received extensive attention. The shrinkage of concrete after setting consists of autogenous shrinkage and drying shrinkage. Both types of shrinkage are related to the drying process of unsaturated pores. When the hydration reaction or water evaporation reduces the internal relative humidity of concrete, the capillary negative pressure increases, causing the autogenous shrinkage or drying shrinkage of the matrix to increase rapidly, exacerbating the shrinkage deformation of concrete. The internal relative humidity of concrete is a key parameter reflecting the drying law of pores. Therefore, it is of great scientific significance to accurately and efficiently analyze the evolution mechanism of concrete shrinkage starting from the internal relative humidity.

[0003] Internal curing is a typical measure to inhibit concrete shrinkage by regulating the internal relative humidity of the matrix. In engineering applications, materials capable of storing water, such as ceramsite and expanded shale, are usually selected and mixed with concrete to construct a uniformly dispersed micro water storage system inside the matrix. When the hydration of cement causes the internal humidity of concrete to decrease, the water storage material slowly releases water under the action of the humidity difference, delaying the rate of decrease of the internal relative humidity and inhibiting the shrinkage of the matrix. However, although internal curing can effectively maintain the pore humidity inside the concrete, the effect of this method generally lacks regularity and cannot efficiently achieve quantitative control of the internal humidity. Therefore, this method is difficult to effectively support the correlation analysis between internal relative humidity and shrinkage. To meet the urgent needs of related research, it is necessary to propose a new experimental device and testing method to quantitatively regulate the internal relative humidity of the matrix and provide technical support for the theoretical research of concrete shrinkage.

[0004] In the prior art, methods for regulating the relative humidity inside concrete through internal curing measures are relatively common. However, this method cannot well achieve quantitative control of the internal relative humidity and is difficult to meet the relevant test requirements. The evolution law of the internal relative humidity is an important index for analyzing concrete shrinkage. However, current testing technologies rarely provide accurate and efficient testing methods. Analyzing the influence mechanism of the changing rate of the internal relative humidity on the time-varying characteristics of shrinkage is not conducive to establishing a complete shrinkage restraint mechanism at the theoretical level and is difficult to provide complete technical guidance for concrete shrinkage control. To overcome the above drawbacks, we take environmental factors, such as the external temperature field or the external humidity field, as analysis variables to adjust the internal relative humidity and achieve the shrinkage test goal. Different from the temperature field, the external humidity field needs to directly act on the concrete surface when the specimen is not sealed, affecting the evaporation rate of the concrete and thus changing the evolution law of the relative humidity inside the matrix. Therefore, an experimental device and method for analyzing the influence of the internal relative humidity on concrete shrinkage by adjusting the external humidity field are proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide an experimental device and method for analyzing the influence of the internal relative humidity on concrete shrinkage by adjusting the external humidity field, which can conveniently prepare thin-walled arc-shaped shrinkage specimens and establish a uniform and controllable humidity field around the shrinkage specimens, thereby ensuring the effective action of the external humidity on the shrinkage specimens, and further realizing quantitative regulation of the changing rate of the internal relative humidity of the specimens, meeting the theoretical research requirements of concrete shrinkage, and solving the problems raised in the above background technology.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: An experimental device for analyzing the influence of the internal relative humidity on concrete shrinkage by adjusting the external humidity field, comprising a shrinkage mold assembly. The shrinkage mold assembly includes a bottom plate. The top of the bottom plate is provided with an outer plate and an inner plate, both of which have semi-circular cross-sections. The inner plate is located inside the outer plate. Both ends of the outer plate and the inner plate are provided with side plates. The top of the bottom plate is provided with a support base assembly for replacing the inner plate. The support base assembly includes multiple groups of semi-circular steel rings and balls arranged in parallel and connected. The balls are connected in series on the parallel semi-circular steel rings; An embedded strain sensor and an embedded humidity sensor are arranged inside the shrinkage mold assembly. The output ends of the embedded strain sensor and the embedded humidity sensor are connected to a controller through wires. The output end of the controller is connected to a humidifier and a dehumidifier through wires. Water tanks are arranged on both sides of the shrinkage mold assembly. The outer plate and the side plates are connected to the humidifier, the dehumidifier, and the water tanks respectively through ducts.

[0007] Preferably, a foam board is arranged between the outer plate and the inner plate, and the upper surface of the foam board is closely attached to the inner wall of the outer plate. A shrinkage specimen in the shape of a semi-circular cross-section of test concrete is arranged between the foam board and the inner plate. The thickness of the shrinkage specimen does not exceed 50 mm. After the foam board is drawn out, an outer plate cavity is formed between the outer plate and the specimen, and a bottom plate cavity is formed between the inner plate and the bottom plate.

[0008] Preferably, the side plate is a rectangular plate. The length and width dimensions of the side plate are respectively equal to the outer diameter of the cross-section of the outer plate and the outer radius dimension. The width of the bottom plate is equal to the outer diameter dimension of the cross-section of the outer plate, and the length of the bottom plate is equal to the length after the two side plates and the outer plate are spliced.

[0009] Preferably, the embedded strain sensor includes an embedded strain gauge, a vibrating wire strain sensor, a non-contact optical sensor, and a distributed optical fiber sensor. The embedded humidity sensor includes a digital humidity sensor, a piezoelectric humidity sensor, and a built-in humidity sensor.

[0010] Preferably, the humidity control range of the humidifier is 60% - 100%, and the humidity control range of the dehumidifier is 20% - 60%.

[0011] Preferably, the spacing between the parallel arrangements of the steel rings does not exceed 2 times the diameter of the ball.

[0012] Preferably, a sealed test box is arranged outside the shrinkage specimen during the long-term shrinkage test. The sealed test box is connected to a humidifier, a dehumidifier, and a water tank respectively through arranged conduits.

[0013] Preferably, ellipsoidal steel balls replacing the balls can also be adopted on the steel rings, and the contour line of the ellipsoidal steel balls matches the curve type of the inner surface of the shrinkage specimen.

[0014] Preferably, an arc-shaped bottom film is arranged on the side of the outer plate away from the bottom plate, and an airbag for replacing the inner plate is arranged in the inner cavity of the outer plate.

[0015] The present invention also provides a test method for analyzing the influence of internal relative humidity on concrete shrinkage by adjusting the external humidity field. The test is carried out by using the above-mentioned test device for analyzing the influence of internal relative humidity on concrete shrinkage by adjusting the external humidity field, and specifically includes the following steps: S1. Assemble the shrinkage mold assembly: First, apply vaseline on the contact surfaces of the inner plate, the side plate, the bottom plate, the foam board and the shrinkage specimen, and spread a plastic film on the surface coated with vaseline. Then, splice the outer plate, the inner plate and the bottom plate into an assembly without a side plate, and then place the foam board inside and make it fit with the inner wall of the outer plate; S2. Install and calibrate the embedded sensors: Position and install the embedded strain sensor and the embedded humidity sensor along the axis of the shrinkage specimen. During the installation process, check the position and direction of the sensors multiple times to ensure that the deviation error between the sensor axis and the target axis does not exceed 2°. After installation, calibrate the sensitivity and initial readings of the sensors; S3. Pour the shrinkage specimen: Install the side plate on one side of the shrinkage mold assembly, then erect the mold. Pour the concrete from the open end on the other side of the mold and vibrate the concrete slowly. After pouring, install another side plate at the open end of the mold and move the mold to the shrinkage test chamber at the same time; S4. Assemble the test system: When the concrete is about to set, place the above-mentioned whole horizontally, remove the side plate, bottom plate and inner plate, replace the inner plate with the support base assembly, then take out the outer plate and the foam board, and place humidity probes in the cavities left by the foam board in the mold and the cavity between the bottom plate and the support base assembly respectively. Remove the covered plastic film, then install the bottom plate, side plate and outer plate back to the mold, and then connect the outer plate with the humidifier, dehumidifier, the outer plate with the water tank, the side plate with the humidifier, dehumidifier, and the side plate with the water tank using conduits. The conduits on the outer plate extend into the outer plate cavity in the mold, and the conduits on the side plate extend into the bottom plate cavity between the bottom plate and the support base assembly. At the same time, connect one end of the embedded strain sensor, embedded humidity sensor, humidifier and dehumidifier to the controller; S5. Test the relative humidity inside the shrinkage specimen: After the concrete has set, read the time-varying data of the relative humidity inside the shrinkage specimen on the controller to obtain the evolution law of the relative humidity inside the shrinkage specimen under the standard environmental humidity. Thereafter, set the test humidity on the controller, and control the humidifier or dehumidifier to introduce gas with the set humidity into the outer plate cavity and the bottom plate cavity to obtain the time-varying characteristics of the relative humidity inside the shrinkage specimen under different humidity conditions; S6. Test the shrinkage of the shrinkage specimen: Combining the evolution law of the relative humidity inside the shrinkage specimen under different external humidity conditions that have been measured, set the controller program to regulate the external humidity field in the outer plate cavity and the bottom plate cavity of the specimen at different test ages, or let the controller intelligently identify the real-time internal relative humidity state and automatically adjust the humidity field value according to the set program, thereby changing the rate of change of the relative humidity inside the concrete, so as to control the relative humidity inside the concrete at the target value at a specific age. At the same time, read the shrinkage results of the shrinkage specimen and analyze the theoretical relationship between the relative humidity inside the concrete and the shrinkage.

[0016] In summary, the present invention has the following beneficial effects: 1. The present invention provides a detachable and assembled arc-section shrinkage mold, and by establishing a controllable temperature rise and fall system on the top and bottom surfaces of the mold, variable control of the external humidity field of the shrinkage specimen is achieved. At the same time, the design of the thin-walled arc specimen enables the effective action of the external humidity along the arc radius, ensuring the effectiveness and stability of the humidity field. The test device is exquisitely constructed and easy to operate, providing a necessary equipment foundation for analyzing the correlation mechanism between the internal relative humidity and shrinkage of concrete. At the same time, through the design of the detachable mold, space is created for establishing a controllable external humidity field around the specimen at the early age stage, so that the correlation analysis test between the internal relative humidity and shrinkage of concrete can be carried out earlier, meeting diverse test requirements.

[0017] 2. The present invention establishes an intelligent environment control system for concrete shrinkage testing. By transmitting the internal relative humidity and shrinkage test data of concrete to the controller, the controller intelligently analyzes the real-time state inside the concrete, and then the setting program in the controller drives the humidification or dehumidification device to work according to the established test requirements, realizing the quantitative analysis of the internal relative humidity and shrinkage of concrete. Compared with the environment control system of traditional curing rooms, the test device and test system of the present invention have the characteristics of small floor area, low energy consumption, high automation degree, good stability, etc., and can efficiently promote the implementation and development of related theoretical research.

[0018] 3. The testing method mentioned in the present invention can accurately measure the early shrinkage of high-strength and ultra-high-strength concrete components with small wall thickness, meeting the needs of new technology research and development under the current industrial upgrading trend, and having great market practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of the early shrinkage test device of the present invention including a ball-supported base assembly; Figure 2 is an exploded view of the components of the shrinkage mold assembly of the present invention; Figure 3 is an assembled schematic diagram of the shrinkage mold assembly without side plates of the present invention; Figure 4 is a partial structure and ball rotation schematic diagram of the ball-supported base assembly with balls of the present invention; Figure 5 is a schematic diagram of the arc-shaped bottom mold component during open-pouring of the present invention; Figure 6 is a schematic diagram of the inflatable airbag component during open-pouring of the present invention; Figure 7 is a schematic diagram of the shrinkage mold before and after airbag inflation during open-pouring of the present invention; Figure 8 is a schematic diagram of the long-term shrinkage test device using a sealed test chamber of the present invention; Figure 9 is a structural schematic diagram of the ball-supported base assembly with ellipsoidal steel balls of the present invention; Figure 10 Schematic diagram of a hollow cylindrical cross-section shrinkage specimen adapted to the test system of the present invention.

[0020] In the figure: 1. Shrinkage mold assembly; 101. Outer panel; 1011. Outer panel cavity; 102. Inner panel; 103. Side panel; 104. Bottom panel; 1041. Bottom panel cavity; 105. Foam board; 2. Embedded strain sensor; 3. Embedded humidity sensor; 4. Humidifier; 5. Dehumidifier; 6. Controller; 7. Water tank; 8. Catheter; 9. Shrinkage specimen; 10. Support base assembly; 1001. Steel ring; 1002. Ball bearing; 1003. Elliptical steel ball; 11. Sealing test box; 12. Arc bottom mold; 13. Airbag. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Embodiment 1: Figures 1 - 4 As shown, a test device for analyzing the influence of internal relative humidity on concrete shrinkage by adjusting the external humidity field comprises a shrinkage mold assembly 1, wherein the shrinkage mold assembly 1 comprises a bottom plate 104, and an outer plate 101 and an inner plate 102, both of which are semicircular arc cross-sections, are arranged on the top of the bottom plate 104, and the inner plate 102 is located in the outer plate 101, and side plates 103 are arranged at both ends of the outer plate 101 and the inner plate 102. A card slot can be provided at the connection between the outer plate 101, the side plate 103 and the bottom plate 104, and they are assembled by detachable splicing. A foam board 105 is arranged between the outer panel 101 and the inner panel 102, and the upper surface of the foam board 105 is tightly attached to the inner wall of the outer panel 101. A shrinkage specimen 9 with a semicircular arc cross-section of test concrete is arranged between the foam board 105 and the inner panel 102. The thickness of the shrinkage specimen 9 does not exceed 50 mm. After the foam board 105 is pulled out, an outer panel cavity 1011 is formed between the outer panel and the specimen 9, and a bottom panel cavity 1041 is formed between the inner panel 102 and the bottom panel 104.

[0023] A support base assembly 10 that can be used to replace the inner plate 102 is provided on the top of the bottom plate 104 for shrinkage test. The support base assembly 10 includes a plurality of groups of semicircular arc steel rings 1001 and balls 1002 that are connected in parallel. The balls 1002 are connected in series to the parallel semicircular arc steel rings 1001. The support base assembly 10 supports the shrinkage specimen 9 and provides space for regulating the humidity field on the bottom surface of the specimen in the early stage.

[0024] Inside the shrinkage mold assembly 1, there are embedded strain sensors 2 and embedded humidity sensors 3. The output ends of the embedded strain sensors 2 and the embedded humidity sensors 3 are connected to a controller 6 through wires. The output end of the controller 6 is connected to a humidifier 4 and a dehumidifier 5 through wires. Water tanks 7 are arranged on both sides of the shrinkage mold assembly 1. The outer plate 101 and the side plate 103 are connected to the humidifier 4, the dehumidifier 5, and the water tanks 7 respectively through arranged conduits 8. The humidifier 4 and the dehumidifier 5 respectively introduce high-humidity air and dry air into the outer plate cavity 1011 and the bottom plate cavity 1041 through the conduit 8, creating space for the establishment of the humidity field at the bottom of the shrinkage specimen 9 in the early age stage after the support base assembly 10 replaces the inner plate 102.

[0025] The following specifically describes this embodiment. The inner diameter of the outer plate 101 is 120 mm, the outer diameter of the inner plate 102 is 60 mm. The lengths of the outer plate 101 and the inner plate 102 are both 500 mm, and the wall thickness is 5 mm. The mold side plate 103 is a rectangular plate with a length of 130 mm, a width of 65 mm, and a wall thickness of 5 mm. The mold bottom plate 104 has a height of 20 mm, a width of 130 mm, and a length of 510 mm. The foam board 105 attached to the inner surface of the outer plate 101 has a thickness of 30 mm, thereby controlling the wall thickness of the shrinkage specimen 9 with an arc-shaped cross-section to be 30 mm.

[0026] According to the device in the above embodiment, a test method for analyzing the influence of internal relative humidity on concrete shrinkage by adjusting the external humidity field is adopted, which specifically includes the following steps: S1. Assemble the shrinkage mold assembly 1: First, apply vaseline on the contact surfaces of the inner plate 102, the side plate 103, the bottom plate 104, and the foam board 105 with the shrinkage specimen 9, and spread a plastic film on the surfaces coated with vaseline. Then, splice the outer plate 101, the inner plate 102, and the bottom plate 104 into an assembly without the side plate 103, and then place the foam board 105 inside and make it fit the inner wall of the outer plate 101. S2. Install and calibrate the embedded sensors: Position and install the embedded strain sensors 2 and the embedded humidity sensors 3 along the axis position of the shrinkage specimen 9. During the installation process, check the sensor position and direction multiple times to ensure that the deviation error between the sensor axis and the target axis does not exceed 2°. After installation, calibrate the sensor sensitivity and the initial reading to ensure the accuracy and reliability of the test results. S3. Pour the shrinkage specimen 9: Install the side plate 103 on one side of the shrinkage mold assembly 1, then erect the mold, pour the concrete from the open end on the other side of the mold, and slowly vibrate the concrete to improve the compactness of the concrete around the embedded strain sensors 2 and the embedded humidity sensors 3, preventing the influence of voids or cracks on the test results. After pouring, install another side plate 103 at the open end of the mold, and at the same time move the mold to the shrinkage test chamber. S4. Assemble the test system: When the concrete is approaching its initial setting, place the above-mentioned whole horizontally, remove the side plate 103, the bottom plate 104 and the inner plate 102, replace the inner plate 102 with the support base assembly 10, then take out the outer plate 101 and the foam board 105, and place humidity sensors at the cavities left by the foam board 105 in the mold and at the cavity between the bottom plate 104 and the support base assembly 10 respectively to check the external humidity of the specimen. Remove the covered plastic film, then install the bottom plate 104, the side plate 103 and the outer plate 101 back to the mold. Then use the conduit 8 to connect the outer plate 101 with the humidifier 4, the dehumidifier 5, the outer plate 101 with the water tank 7, the side plate 103 with the humidifier 4, the dehumidifier 5, and the side plate 101 with the water tank 7. The conduit 8 on the outer plate 101 extends into the outer plate cavity 1011 inside the mold, and the conduit 8 on the side plate 103 extends into the bottom plate cavity 1041 between the bottom plate 104 and the support base assembly 10. At the same time, connect one end of the embedded strain sensor 2, the embedded humidity sensor 3, the humidifier 4 and the dehumidifier 5 to the controller 6; S5. Test the relative humidity inside the shrinkage specimen 9: After the concrete has initial set, read the time-varying data of the relative humidity inside the shrinkage specimen 9 on the controller 6 to obtain the evolution law of the relative humidity inside the shrinkage specimen 9 under the standard environmental humidity. Thereafter, set the test humidity on the controller 6, and control the humidifier 4 or the dehumidifier 5 to introduce gas with the set humidity into the outer plate cavity 1011 and the bottom plate cavity 1041 to obtain the time-varying characteristics of the relative humidity inside the shrinkage specimen 9 under different humidity conditions; S6. Test the shrinkage of the shrinkage specimen 9: Combining the evolution law of the relative humidity inside the shrinkage specimen 9 under different external humidity conditions that have been measured, set the program of the controller 6 to regulate the external humidity field in the outer plate cavity 1011 and the bottom plate cavity 1041 of the specimen at different test ages, or let the controller 6 intelligently identify the real-time internal relative humidity state and automatically adjust the humidity field value according to the set program, thereby changing the rate of change of the relative humidity inside the concrete, so as to control the relative humidity inside the concrete at the target value at a specific age. At the same time, read the shrinkage result of the shrinkage specimen 9 and analyze the theoretical relationship between the relative humidity inside the concrete and the shrinkage.

[0027] Embodiment 2: As Figure 9As shown in the figure, the difference from the first embodiment is that the ball 1002 in the support base assembly 10 is replaced by an ellipsoidal steel ball 1003, and the contour line of the ellipsoidal steel ball 1003 matches the curve type of the inner surface of the shrinkage specimen 9. Thus, the multi-point support method of the ball 1002 for the shrinkage specimen 9 is adjusted to the multi-line support method of the ellipsoidal steel ball 1003 for the shrinkage specimen 9, improving the stress concentration problem on the contact surface and enhancing the stability and reliability of the support of the support base assembly 10. The movement mode structure of the ellipsoidal steel ball 1003 is the same as that of the ball 1002. The ellipsoidal steel ball 1003 cannot slide and can only rotate, thereby ensuring that the axial shrinkage of the shrinkage specimen 9 is not affected when the support base assembly 10 supports. This embodiment requires the ellipsoidal steel ball 1003 and the shrinkage specimen 9 to fit each other in terms of structural dimensions, increasing the difficulty of processing and mold making, but it can better play the supporting role of the support base assembly 10 and improve the accuracy of the test.

[0028] Embodiment Three: As Figures 5 - 7 shown, the difference from the first embodiment is that by setting Figures 5 - 6 the arc-shaped bottom mold 12 and the airbag 13 in, the vertical pouring method of pouring from the position of the side plate 103 of the mold in the first embodiment is changed to Figure 7 the open-pouring method of directly pouring on the foam board 105 in, thereby effectively increasing the pouring area of the mold and solving the problems of difficult pouring and low density of low-fluidity concrete. To implement this embodiment, the arc-shaped bottom mold 12 is used to support the outer plate 101, and the inner plate 102 is removed during mold making, and the uninflated airbag 13 is placed. After pouring the concrete, the airbag 13 is inflated through the air vent hole on the side plate 103. As Figure 6 shown, the cross-section of the airbag 13 is semi-circular after inflation, and the outer diameter of the cross-section of the airbag 13 is the same as the inner diameter of the inner plate 102, thus playing the role of replacing the inner plate 102 to prepare the thin-walled shrinkage specimen 9. Before the test, the support base assembly 10 is used to replace the airbag 13, and then the shrinkage test is carried out with reference to steps 4 to 6 in the test steps of the first embodiment. This embodiment enriches the preparation method of the specimen 9 and can better meet the shrinkage test requirements of different concretes. Embodiment Four: As Figure 8 shown, the difference from the first embodiment is that this embodiment is mainly used to analyze the relationship between the relative humidity inside the concrete and the long-term shrinkage. The corresponding shrinkage start measurement time is adjusted from the initial setting of the concrete to after the shrinkage specimen 9 is demolded and cured. The shrinkage specimen 9 does not need to be tested with the mold. Therefore, the demolded shrinkage specimen 9 is placed in the sealed test chamber 11, and the conduit 8 connecting the humidifier 4, the dehumidifier 5, the water tank 7 and the shrinkage mold assembly 1 in the first embodiment is connected to the sealed test chamber 11. Thereafter, the test method refers to steps 5 and 6 in the test steps of the first embodiment. The application of the sealed test chamber 11 and the adjustment of the test system increase the test space and improve the test operability, thereby realizing the synchronous test of multiple groups of shrinkage specimens 9 while facilitating monitoring.

[0029] Among them, in the fourth embodiment, since the shrinkage test is carried out after the shrinkage specimen 9 is demolded and cured, there is no need to consider the problem that the concrete in the early age stage has not hardened and the strength is insufficient when formulating the cross-section style of the shrinkage specimen 9. Therefore, the cross-section style of the shrinkage specimen 9 is more abundant. Since the production of the shrinkage specimen 9 with a semi-circular arc cross-section is difficult, specimens with a hollow cylindrical cross-section with relatively simple structure can be used in the long-term shrinkage test, such as Figure 10 shown. Compared with the shrinkage specimen 9 with a semi-circular arc cross-section, the template style of the hollow cylindrical cross-section has the characteristics of strong versatility and low implementation cost. Therefore, the difficulty of mold making and pouring of the shrinkage specimen 9 is greatly reduced. Among them, the shrinkage specimen 9 with a hollow cylindrical cross-section has higher requirements for template support and more constraints in the early stage, which is not conducive to improving the accuracy of early shrinkage test. In the long-term shrinkage test, after the shrinkage specimen 9 with a hollow cylindrical cross-section reaches a certain strength, the support template can be removed and then the shrinkage test can be carried out. The test method refers to the fourth embodiment.

[0030] It should be noted that in this article, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0031] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A test device for analyzing the effect of internal relative humidity on concrete shrinkage by adjusting an external humidity field, comprising a shrinkage mold assembly (1), wherein the shrinkage mold assembly (1) comprises a bottom plate (104), an outer plate (101) and an inner plate (102) both of which have semicircular arc cross-sections are arranged on the top of the bottom plate (104), the inner plate (102) is located inside the outer plate (101), and side plates (103) are arranged at both ends of the outer plate (101) and the inner plate (102), characterized in that: A support base assembly (10) that can be used to replace the inner plate (102) is arranged on the top of the bottom plate (104), and the support base assembly (10) comprises a plurality of groups of semi-circular arc steel rings (1001) and balls (1002) that are connected in parallel, and the balls (1002) are connected in series on the parallel semi-circular arc steel rings (1001); An embedded strain sensor (2) and an embedded humidity sensor (3) are arranged inside the shrink mold assembly (1); the output ends of the embedded strain sensor (2) and the embedded humidity sensor (3) are connected to a controller (6) via a line; the output end of the controller (6) is connected to a humidifier (4) and a dehumidifier (5) via a line; water tanks (7) are arranged on both sides of the shrink mold assembly (1); the outer plate (101) and the side plate (103) are respectively connected to the humidifier (4), the dehumidifier (5) and the water tank (7) via a conduit (8).

2. A test device for analyzing the effect of internal relative humidity on concrete shrinkage by adjusting the external humidity field according to claim 1, characterized in that: A foam plate (105) is arranged between the outer plate (101) and the inner plate (102), and the upper surface of the foam plate (105) is closely attached to the inner wall of the outer plate (101). A shrinkage test piece (9) in the shape of a semicircular arc cross section for testing concrete is arranged between the foam plate (105) and the inner plate (102), and the shrinkage test piece (9) has a thickness of no more than 50 mm. After the foam plate (105) is pulled out, an outer plate cavity (1011) is formed between the outer plate and the test piece (9), and a bottom plate cavity (1041) is formed between the inner plate (102) and the bottom plate (104).

3. The test device for analyzing the effect of internal relative humidity on concrete shrinkage by adjusting the external humidity field according to claim 1, characterized in that: The side panels (103) are rectangular panels, the length and width of the side panels (103) are respectively equal to the cross-sectional outer diameter and outer radius of the outer panel (101), the width of the bottom panel (104) is equal to the cross-sectional outer diameter of the outer panel (101), and the length of the bottom panel (104) is equal to the length of the side panels (103) on both sides and the outer panel (101) after being spliced.

4. The test device for analyzing the effect of internal relative humidity on concrete shrinkage by adjusting the external humidity field according to claim 1, characterized in that: The embedded strain sensor (2) comprises an embedded strain gauge, a vibrating wire strain sensor, a non-contact optical sensor and a distributed optical fiber sensor, and the embedded humidity sensor (3) comprises a digital humidity sensor, a piezoelectric humidity sensor and a built-in humidity sensor.

5. The test device for analyzing the effect of internal relative humidity on concrete shrinkage by adjusting the external humidity field according to claim 1, characterized in that: The humidity control range of the humidifier (4) is 60% to 100%, and the humidity control range of the dehumidifier (5) is 20% to 60%.

6. The test device for analyzing the effect of internal relative humidity on concrete shrinkage by adjusting the external humidity field according to claim 1, characterized in that: The spacing between the parallel arrangement of the steel rings (1001) does not exceed twice the diameter of the ball (1002).

7. The test device for analyzing the effect of internal relative humidity on concrete shrinkage by adjusting the external humidity field according to claim 1, characterized in that: When the shrinkage test piece (9) is subjected to a long-term shrinkage test, a sealed test box (10) is arranged outside the shrinkage test piece (9), and the sealed test box (10) is respectively connected to the humidifier (4), the dehumidifier (5) and the water tank (7) via a conduit (8).

8. The test device for analyzing the effect of internal relative humidity on concrete shrinkage by adjusting the external humidity field according to claim 1, characterized in that: The steel ring (1001) may also be provided with an ellipsoidal steel ball (1003) instead of the rolling ball (1002), and the contour line of the ellipsoidal steel ball (1003) matches the curve line shape of the inner surface of the shrinkage test piece (9).

9. The test device for analyzing the effect of internal relative humidity on concrete shrinkage by adjusting the external humidity field according to claim 1, characterized in that: A curved bottom membrane (12) is provided on a side of the outer plate (101) away from the bottom plate (104), and an air bag (13) that can be used to replace the inner plate (102) is provided in the inner cavity of the outer plate (101).

10. A test method for analyzing the effect of internal relative humidity on concrete shrinkage by adjusting the external humidity field, characterized in that: The test device for analyzing the effect of internal relative humidity on concrete shrinkage by adjusting the external humidity field as described in any one of claims 1 to 9 is used, and specifically comprises the following steps: S1, assembling the shrink mold assembly (1): first, applying vaseline on the contact surfaces of the inner plate (102), the side plate (103), the bottom plate (104) and the foam plate (105) with the shrink test piece (9), and spreading a plastic film on the surface coated with vaseline, then assembling the outer plate (101), the inner plate (102) and the bottom plate (104) into an assembly without the side plate (103), and then placing the foam plate (105) inside and making it fit with the inner wall of the outer plate (101); S2. Install and calibrate the embedded sensors: Position and install the embedded strain sensor (2) and the embedded humidity sensor (3) along the axis of the shrinkage specimen (9). During the installation process, check the position and direction of the sensors several times to ensure that the deviation error between the sensor axis and the target axis does not exceed 2°. After installation, calibrate the sensor sensitivity and initial reading. S3, casting shrinkage test piece (9): installing a side plate (103) on one side of the shrinkage mold assembly (1), then erecting the mold, pouring concrete from the open opening on the other side of the mold, and slowly vibrating the concrete. After the casting is completed, another side plate (103) is installed at the open opening of the mold, and the mold is moved to the shrinkage test room; S4. Assemble the test system: When the concrete is about to set, lay the whole body flat, remove the side panels (103), the bottom panel (104) and the inner panel (102), replace the inner panel (102) with the support base assembly (10), then take out the outer panel (101) and the foam panel (105), respectively place the humidity probe in the cavity left by the foam panel (105) in the mold and in the cavity between the bottom panel (104) and the support base assembly (10), remove the covering plastic film, then install the bottom panel (104), the side panel (103) and the outer panel (101) back into the mold, and then use the conduit (8) to connect the outer panel (101). 01) and a humidifier (4), a dehumidifier (5), an outer plate (101) and a water tank (7), a side plate (103) and a humidifier (4), a dehumidifier (5), and a side plate (101) and a water tank (7), wherein the conduit (8) on the outer plate (101) extends into an outer plate cavity (1011) in a mold, and the conduit (8) on the side plate (103) extends into a bottom plate cavity (1041) between a bottom plate (104) and a supporting base assembly (10), and at the same time, one end of the embedded strain sensor (2), the embedded humidity sensor (3), the humidifier (4) and the dehumidifier (5) are connected to a controller (6); S5, testing the relative humidity inside the shrinkage test piece (9): after the concrete is initially set, the time-varying data of the relative humidity inside the shrinkage test piece (9) is read on the controller (6) to obtain the evolution law of the relative humidity inside the shrinkage test piece (9) under the standard ambient humidity. Thereafter, the test humidity is set on the controller (6), and the humidifier (4) or the dehumidifier (5) is controlled to introduce gas with the set humidity into the outer plate cavity (1011) and the bottom plate cavity (1041), so as to obtain the time-varying characteristics of the relative humidity inside the shrinkage test piece (9) under different humidity conditions; S6. Testing the shrinkage of the shrinkage specimen (9): Based on the evolution law of the relative humidity inside the shrinkage specimen (9) under different external humidity conditions that have been measured, the controller (6) program is set to control the external humidity field inside the specimen outer plate cavity (1011) and the bottom plate cavity (1041) at different test ages, or the controller (6) intelligently identifies the real-time internal relative humidity state and automatically adjusts the humidity field value according to the set program, thereby changing the rate of change of the relative humidity inside the concrete, thereby controlling the relative humidity inside the concrete to a target value at a specific age, and at the same time reading the shrinkage result of the shrinkage specimen (9) to analyze the theoretical relationship between the relative humidity inside the concrete and shrinkage.

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