Concrete test mold for salinized soil erosion environment and durability test method

Abstract

The invention relates to the technical field of concrete tests, in particular to a concrete test mold for a salinization soil erosion environment and a durability test method.The concrete test mold comprises the concrete test mold, a mold pressing device and a support, the mold pressing device is connected to the lower portion of the support through a lifting driving part, and the concrete test mold is located under the mold pressing device; the concrete test mold is composed of a test mold frame and a movable partition plate, and the movable partition plate is matched with the test mold frame to form concrete forming areas and salinized soil forming areas of different sizes. Different test mold sizes are formed by adjusting the positions of the key grooves where the movable partition plates are located, compared with an existing size-adjustable test mold, the test mold is more flexible and convenient to adjust, assembly and disassembly of the test mold mainly depend on the test mold frame and the key grooves formed in the movable partition plates, and compared with traditional fixing bolts, operation is simpler, and the test mold is more convenient to use. And the formed test piece is high in precision.

Description

Technical Field

[0001] The invention relates to the technical field of concrete testing, and in particular to a concrete test mold and a durability testing method for a salinized soil erosion environment. Background Art

[0002] Arid and semi-arid areas are affected by climate and human agricultural activities, and usually have large areas of salinized soil. The parts of hydraulic concrete buildings built in these areas above the surface are usually subject to erosion by salt solutions, dry-wet cycles, freeze-thaw cycles and other environmental effects, but hydraulic concrete buildings below the surface are subject to erosion by salinized soil. The salt ions (chloride ions, sulfate ions, sodium ions, calcium ions, etc.) in the salinized soil may corrode the concrete buildings as the water in the soil moves, which can also easily cause problems such as reduced durability of concrete materials and rust of steel bars.

[0003] Traditionally, the durability of concrete is usually studied indoors through accelerated degradation tests, such as concrete salt corrosion tests, wet-dry cycle tests, and freeze-thaw cycle tests. The test generally places the prepared target concrete specimens in salt corrosion solutions, wet-dry cycle machines, and freeze-thaw cycle machines. This type of test method can only study the durability of concrete under water or salt solution corrosion. Solid corrosives such as salinized soil are prone to collapse under these experimental conditions. At present, there is a lack of durability test methods and test molds for concrete materials wrapped in salinized soil and in complex corrosive environments. Therefore, it is difficult to carry out concrete durability tests under solid corrosive conditions such as salinized soil.

[0004] To conduct durability test research on concrete in salinized soil erosion environment, it is necessary to place concrete test blocks in salinized soil erosion environment, which includes salinized soil constant temperature and humidity environment, dry-wet cycle, freeze-thaw cycle, dry-wet-freeze-thaw cycle, etc. To conduct concrete durability test, it is necessary to make target concrete test blocks in advance through concrete test molds. Traditional concrete test molds mainly include cube test molds, rectangular test molds and cylindrical test molds. For example, the patent authorization number CN 220661257 U discloses a combined concrete test mold, which simplifies the difficulty of applying release agent and cleaning through the combination of supporting bottom plate, integral fixed side plate and mutually lockable partition combination. And through the combination of mutually lockable partitions, the molding of multiple groups of test blocks can be completed at one time, which is conducive to batch operation. However, the current concrete test molds can only produce concrete test blocks of different sizes. After the test pieces are demolded, there is no space or facilities around them for attaching and fixing salinized soil and other loose erosion media. It is impossible to create a salinized soil erosion environment with different compaction degrees, moisture content or salt content in the laboratory. There are certain differences between the test environment and the actual environment. It is impossible to accurately study the durability of concrete materials under salinized soil erosion, dry-wet cycles, freeze-thaw cycles, dry-wet-freeze-thaw cycles and other environments. There are defects and shortcomings in studying the erosion of concrete in salinized soil environments. Summary of the invention

[0005] In view of the above-mentioned defects and problems, the present invention provides a concrete test mold and a durability test method for a salinized soil erosion environment. An innovative concrete test mold capable of creating a salinized soil erosion environment and a concrete durability test method used in conjunction with existing equipment such as an oven and a freeze-thaw cycler are designed to achieve the purpose of durability test research on concrete materials under the action of salinized soil erosion.

[0006] The solution adopted by the present invention to solve the technical problem is: a concrete test mold for a salinized soil erosion environment, comprising a concrete test mold, a die pressing device and a bracket, wherein the die pressing device is connected to the bottom of the bracket through a lifting drive member, and the concrete test mold is located directly below the die pressing device. The concrete test mold is composed of a test mold frame and a movable partition, wherein the movable partition comprises a group of longitudinal partitions, a group of transverse partitions and a horizontal partition, and the inner walls of the test mold frame and the movable partition are provided with a plurality of key slots in the transverse and longitudinal directions, and the longitudinal partitions, the transverse partitions and the horizontal partitions can be snapped into the key slots and cooperate with the test mold frame to form concrete molding areas and salinized soil molding areas of different sizes; The die pressing device comprises a die pressing group, which is composed of a large die pressing body, a medium die pressing body and a small die pressing body which are sequentially mounted. The size of the die pressing body matches the surface size of the salinized soil molding area and is used to evenly apply static pressure during the salinized soil molding process. A pressure column group is vertically arranged above each die pressing body. Each pressure column of the pressure column group is sequentially mounted, and each pressure column is connected by a limiting bolt. The outermost large pressure column is connected to the bottom of the bracket by a lifting drive member. The internal structures of the large die body, the medium die body and the small die body are the same, all of which are hollow structures, and a water seepage plate is arranged inside the die body, which divides the die body into a water storage cavity and a pressing groove up and down. A pressing plate is detachably installed in the pressing groove, and the pressing plates at the bottom of each die body are in the same horizontal plane in the initial state.

[0007] Furthermore, the test mold frame is composed of two isosceles right triangle structures of the same size, which can be combined to form a square test mold frame. The inner wall of the test mold frame is provided with multiple groups of horizontal key grooves and vertical key grooves, and the key groove width matches the thickness of the partition. The horizontal key grooves on the test mold frame are used to fix and adjust the position of the horizontal partition, and the vertical key grooves are used to fix and adjust the position of the longitudinal partition. The inner wall of the longitudinal partition is also provided with vertical key grooves for fixing and adjusting the position of the transverse partition.

[0008] Furthermore, the movable partition can cooperate with the test mold frame to form three salinized soil forming areas of different sizes, namely a large forming area, a medium forming area and a small forming area, and the concrete forming area changes adaptively according to the size of the salinized soil forming area.

[0009] Furthermore, a large pressure column, a medium pressure column and a small pressure column are vertically arranged above the large pressure mold body, the medium pressure mold body and the small pressure mold body respectively, the small pressure column is longitudinally movably mounted in the medium pressure column, the medium pressure column is longitudinally movably mounted in the large pressure column, and limiting rings are arranged in the medium pressure column and the large pressure column for limiting the internal pressure columns.

[0010] Furthermore, the water seepage plate is provided with mounting screw holes on the left and right sides, and the pressing plate is rotatably sleeved with mounting bolts, and the pressing plate is installed in the pressing groove of the pressing mold body through the mounting bolts.

[0011] Furthermore, bolt fixing holes are provided at the two isosceles right triangle interfaces of the test mold frame for fixing the test mold frame.

[0012] Furthermore, each die body is provided with a water inlet connected to the water storage cavity, and the large die body and the medium die body are provided with an operating slot for exposing the water inlet on the inner die body.

[0013] A durability test method for a salinized soil erosion environment comprises the following steps: S1. Two isosceles right triangle frames are butt-jointed by fixing bolts to form a square test mold frame. During the butt-jointing process, the horizontal partition in the movable partition is embedded into the horizontal keyway of the test mold frame; S2, embed a set of two longitudinal partitions into the vertical keyway on the test mold frame, and embed the bottom of the longitudinal partition into the horizontal keyway on the horizontal partition; S3, insert a set of two transverse partitions into the vertical keyway on the longitudinal partition. At this time, the area surrounded by the horizontal partition, the longitudinal partition and the transverse partition is the concrete specimen forming area; the outer area is the salinized soil forming area; S4, fill the mixed target concrete into the concrete specimen molding area, demould after vibration, leveling, and initial setting, and put it into the molding area again after curing in the standard curing room; S5. Prepare a salinized soil sample with a target required moisture content, calculate the required soil weight according to the volume of the salinized soil forming area and the target compaction degree, place the soil in the salinized soil forming area, and press the soil sample into the forming area through a pressing mold device to form a salinized soil area with a target moisture content and compacted soil; S6. After the sample is prepared, a concrete test block simulating the salinized soil erosion environment is formed and subsequent durability tests are carried out.

[0014] Furthermore, in steps S1-S3, the size of the concrete test mold can be adjusted by changing the position of the keyway where the movable partition is located to meet the needs of making concrete specimens of different sizes.

[0015] Furthermore, after the specimen is made, the test mold frame is removed, the outer wall of the soil sample is wrapped with a latex film, and a permeable stone is placed on the upper and lower surfaces to control the migration of moisture only through the two ends of the specimen, approximately simulating the one-dimensional migration of moisture. After the specimen is immersed in clean water to the saturated moisture content of the soil, the specimen is taken out and placed in an oven, and dried to the lower limit of the soil moisture content. According to the standard of ASTMD4843-88, a dry-wet cycle alternating test is carried out to determine the durability changes of concrete during the dry-wet cycle erosion of salinized soil.

[0016] Furthermore, the freeze-thaw cycle erosion test of concrete subjected to salinized soil is carried out in a closed space. On the basis of the above, the sample is wrapped by an inner layer of latex film and breathable stone, and then the sealed bag sample is wrapped for a second time, and finally placed in a sealed box for a third sealing. According to the standard of ASTM D560 / D560M-16, the freeze-thaw cycle alternation test is carried out, and the durability index of the concrete is determined after several freeze-thaw cycles to complete the freeze-thaw cycle erosion test of concrete subjected to salinized soil.

[0017] Furthermore, on the basis of the above tests, a simulation experiment on the concrete being subjected to alternating dry-wet freeze-thaw cycles was conducted indoors using four stages of wetting-drying-freezing-thawing. After several of the above cycles, the durability index of the concrete was measured to complete the concrete erosion test subjected to alternating dry-wet freeze-thaw cycles in salinized soil.

[0018] Beneficial effects of the present invention: In view of the problem that the existing concrete test molds can only be produced in fixed sizes, the test mold designed in the present invention has multiple key slots at different positions on the side walls, and different test mold sizes can be formed by adjusting the position combination of the key slots where the movable partition is located. Compared with the existing adjustable size test molds, it is more flexible and convenient to adjust. The assembly and disassembly of the test mold mainly rely on the key slots set on the test mold frame and the movable partition. Compared with traditional fixing bolts, it is simpler to operate and the molding test piece has higher precision. At the same time, the present invention is not limited to the number and position of the slots shown in the figure, and the size can be customized according to the size adjustment idea described in the present invention.

[0019] In order to solve the problem that salinized soil cannot be attached and fixed around the concrete specimen after demolding, forming a salinized soil erosion environment, the present invention only removes or moves the partition position during the demolding stage of the test mold, retains the frame part around the test mold, and forms a space (soil storage area) for storing salinized soil between the specimen and the test mold frame (or partition), so that the salinized soil around the specimen can be attached and fixed after demolding.

[0020] In view of the problem that salinized soil in different physical states has different erosion effects on concrete, the salinized soil required for the test mold designed by the present invention is generally sampled from the location of the research object, and the moisture content and compaction of the salinized soil in the test mold are determined according to the designed moisture content and compaction of the backfill soil of the specific concrete project. The test mold is equipped with a pressing mold device with the same size as the surface of the salinized soil attachment and fixing area. With reference to the soil sample preparation method-sampling method in the geotechnical test method standard (GBT 50123-2019), the soil sample is pressed into the soil storage area by applying static pressure to form a salinized soil environment with a target moisture content and compaction.

[0021] In view of the problem that there is currently no clear indoor accelerated degradation test method for concrete affected by salinized soil erosion (dry-wet cycle, freeze-thaw cycle, dry-wet freeze-thaw cycle, etc.), the concrete affected by salinized soil erosion test mold invented in this invention can be used in conjunction with a constant temperature and humidity test chamber to carry out long-term durability tests of concrete affected by salinized soil erosion; it can be used in conjunction with an oven to carry out accelerated degradation tests of concrete affected by salinized soil dry-wet cycle; it can be used in conjunction with a freeze-thaw cycle machine to carry out accelerated degradation tests of concrete affected by salinized soil freeze-thaw cycle; and dry-wet cycle can also be combined with freeze-thaw cycle to carry out accelerated degradation tests of concrete affected by salinized soil dry-wet-freeze-thaw alternating cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the concrete test mold of the present invention; Figure 2 It is a schematic diagram of the explosion structure of the concrete test mold of the present invention; Figure 3 Schematic diagram of three sizes of concrete test molds of the present invention; Figure 4 It is a structural schematic diagram of the concrete test mold and pressing mold device of the present invention; Figure 5 It is a schematic diagram of the front cross-sectional structure of the die pressing device of the present invention; Figure 6 It is a schematic diagram of the overall structure of the die pressing device of the present invention; Figure 7 It is a schematic diagram of the exploded structure of the die pressing device of the present invention; Figure 8 It is a schematic diagram of the structure of the die body of the present invention.

[0023] In the figure: 1, concrete test mold; 11, test mold frame; 111, vertical keyway; 112, horizontal keyway; 12, longitudinal partition; 13, transverse partition; 14, horizontal partition; 15, bolt fixing hole; 16, saline soil molding area; 16a, large molding area; 16b, medium molding area; 16c, small molding area; 161, molding area one; 162, molding area two; 163, molding area three; 164, molding area four; 17, concrete molding area Mold area; 2, die pressing device; 21, die pressing group; 21a, large die body; 21b, medium die body; 21c, small die body; 22, pressure column group; 22a, large pressure column; 22b, medium pressure column; 22c, small pressure column; 23, limiting bolt; 24, water storage chamber; 25, seepage plate; 26, pressure plate; 27, mounting bolt; 28, mounting screw hole; 29, water inlet; 210, operating slot; 3, bracket; 4, lifting drive member. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0025] See also Figure 1-8 The present invention provides a technical solution for a concrete test mold and a durability test method for a salinized soil erosion environment: Embodiment 1: This embodiment provides a concrete test mold for a salinized soil erosion environment. Figure 4As shown, it includes a concrete test mold 1, a pressing mold device 2 and a bracket 3. The pressing mold device 2 is connected to the bottom of the bracket 3 through a lifting drive 4. The concrete test mold 1 is directly below the pressing mold device 2. A concrete molding area 17 and a salinized soil molding area 16 are provided in the concrete test mold 1. The lifting drive 4 can drive the pressing mold device 2 to move downward to compact and mold the soil in the salinized soil molding area 16.

[0026] The specific structure of the concrete test mold 1 is as follows Figure 1 and Figure 2 As shown, it is composed of a test mold frame 11 and a movable partition. The test mold frame 11 is composed of two isosceles right triangle structures of the same size. The size is determined according to the size requirements of the test specimen. When in use, it can be combined to form a square test mold frame 11. The main function is to fix the movable partition, and together with the partition, form a concrete molding area 17 and a salinized soil molding area 16, which are used to mold concrete specimens and attach and fix the required salinized soil. Fixing bolts need to be set at the two isosceles right triangle interfaces of the test mold frame 11 to fix the test mold frame and prevent the test mold frame from deforming during the specimen molding process; the movable partition includes a group (two) of longitudinal partitions 12, a group (two) of transverse partitions 13 and a horizontal partition 14. The movable partition cooperates with the test mold frame 11 to form the concrete molding area 17 and the salinized soil molding area 16. The movable partition mainly plays the role of supporting the specimen. The inner wall of the test mold frame 11 and the movable partition is provided with a plurality of key slots in the horizontal and vertical directions. The longitudinal partition 12, the transverse partition 13 and the horizontal partition 14 can be snapped into the key slots and cooperate with the test mold frame 11 to form concrete molding areas and saline soil molding areas of different sizes. The inner wall of the test mold frame 11 is provided with a horizontal keyway 112 and a vertical keyway 111, and the width of the keyway is the same as the thickness of the longitudinal partition 12 and the horizontal partition 14 (or slightly larger than the thickness of the partition), so that the partition can be fixed in the keyway with as little gap as possible, wherein at least two horizontal keyways 112 are provided on the test mold frame 11, and the arrangement method is to be one circle along the inner wall of the frame, mainly used to fix the horizontal partition 14 and adjust the position of the horizontal partition; at least four vertical keyways 111 are provided on the test mold frame 11 (2 pairs), and the arrangement method is to be vertically arranged along the inner walls of both sides of the frame, and mainly used to fix or change the position of the longitudinal partition 12 during the specimen molding process. In this embodiment, six vertical keyways (3 pairs) are provided.

[0027] The size of the horizontal partition 14 matches the size of the horizontal key slot 112 in the assembled test mold frame to ensure that the horizontal partition 14 can be embedded in the horizontal key slot 112 of the test mold frame. It mainly serves as the bottom plate of the concrete specimen molding area and the bottom plate for fixing the salinized soil. The height of the concrete specimen and the thickness of the salinized soil at the bottom of the concrete specimen can be changed by adjusting the position of the horizontal key slot on the test mold frame where the bottom plate is located. In addition, several groups of longitudinal key slots are symmetrically arranged on the horizontal partition 14, which are mainly used to fix the bottom position of the longitudinal partition 12 to prevent the bottom of the longitudinal partition 12 from moving during the specimen molding process, causing specimen size errors.

[0028] The size of the longitudinal partition 12 matches the vertical key groove 111 in the test mold frame after assembly, ensuring that the two longitudinal partitions 12 can be embedded in the two pairs of vertical key grooves 111 in the test mold frame, which mainly form the side panels of the concrete specimen molding area. The two longitudinal partitions 12 respectively form the molding area 161 and the molding area 163 of the salinized soil between the inner wall of the test mold frame 11 and the horizontal partition 14; the width of the concrete specimen and the thickness of the salinized soil molding are changed by moving the positions of the vertical key grooves on the test mold frame where the two longitudinal partitions are located; a plurality of groups of vertical key grooves are symmetrically arranged on the opposite surfaces of the two longitudinal partitions 12, which are mainly used to fix the transverse partition 13.

[0029] Several groups of transverse partitions 13 are arranged, each group has 2 and the same size. The size of the transverse partitions 13 is the same as the spacing between the vertical keyways on different groups of longitudinal partitions 12, ensuring that the transverse partitions 13 can be embedded in the vertical keyways on the longitudinal partitions 12. They mainly form the side panels of the concrete specimen molding area. The transverse partitions 13 and the inner walls of the longitudinal partitions 12 are enclosed to form a concrete molding area 17. The outer walls of the transverse partitions 13 and the longitudinal partitions 12 and the test mold frame 11 are enclosed to form molding areas 162 and 164 of salinized soil. The length of the concrete specimen can be changed by moving the positions of the vertical keyways on the longitudinal partitions 12 where the two transverse partitions 13 are located.

[0030] Here Figure 3 For example, the movable partition can cooperate with the test mold frame 11 to form three salinized soil forming areas 16 of different sizes, namely a large forming area 16a, a medium forming area 16b and a small forming area 16c, and the concrete forming area 17 changes according to the size adaptability of the salinized soil forming area 16.

[0031] After the test mold is assembled, there will be several unused keyways in the concrete molding area. Due to the existence of empty keyways in the concrete molding area, the target concrete specimen after molding may not be a standard cube. The bottom and sides of the concrete specimen will form some redundant edges due to the protrusions of the keyways. In order to solve this problem, several components corresponding to the keyway size can be configured. When the concrete is molded, the components are first filled into the unused empty keyways in the concrete molding area to make the wall surface of the concrete molding area flat, ensuring that the concrete is a standard cube after molding. Example

[0032] On the basis of the first embodiment, Figure 6 - Figure 8 As shown, the die pressing device 2 includes a die pressing group 21 formed by three die pressing bodies which are sequentially assembled, including a large die pressing body 21a, a medium die pressing body 21b and a small die pressing body 21c. The die pressing group 21 is used to evenly apply static pressure during the forming process of salinized soil, and the size of the die pressing group matches the surface size of the salinized soil forming area 16, that is, the size of the large die pressing body 21a matches the size of the small forming area 16c, the size of the large die pressing body 21a plus the medium die pressing body 21b matches the size of the medium forming area 16b, and the size of the large die pressing body 21a plus the medium die pressing body 21b plus the small die pressing body 21c matches the size of the large forming area 16a.

[0033] A pressure column group 22 is vertically arranged above each pressure die body, that is, a large pressure column 22a, a medium pressure column 22b and a small pressure column 22c are vertically arranged above the large pressure die body 21a, the medium pressure die body 21b and the small pressure die body 21c, respectively. The small pressure column 22c is longitudinally movably mounted in the medium pressure column 22b, and the medium pressure column 22b is longitudinally movably mounted in the large pressure column 22a. Limiting rings are arranged in the medium pressure column 22b and the large pressure column 22a for limiting the internal pressure columns. Bolt holes are opened at corresponding positions on each pressure column. Each pressure column can be connected together by limiting bolts 23, or the two outermost pressure columns can be selectively connected together. The outermost large pressure column 22a is connected to the bottom of the bracket 3 through a lifting drive 4, and the lifting drive can adopt an electric push rod or a hydraulic cylinder.

[0034] When the soil in the saline soil forming area 16 is compacted, a die set 21 of matching size can be selected according to the size of the saline soil forming area 16: if the saline soil forming area 16 is a small forming area 16c, the limiting bolt 23 is removed, and the lifting drive member 4 controls the die set 21 to move downward. When the die set 21 contacts the test mold frame 11, the medium-sized die body 21b and the small-sized die body 21c are supported on the solidified concrete surface, and only the large-sized die body 21a continues to be controlled to move downward, so as to compact the soil in the small-sized forming area 16c. The salinized soil is compacted and formed; if the salinized soil forming area 16 is a medium-sized forming area 16b, the large pressure column 22a and the medium-sized pressure column 22b are connected together by limiting bolts 23, and the above steps are taken to compact the soil in the medium-sized forming area 16b; if the salinized soil forming area 16 is a large-sized forming area 16a, all three pressure columns are connected together by limiting bolts 23, and the above steps are taken to compact the soil in the large-sized forming area 16a, so that the soil can be evenly compressed to form salinized soil with a target compaction degree.

[0035] By setting up multiple die bodies and controlling the operation of the multiple die bodies by limiting the bolts 23 and the lifting drive member, the die group 21 can make adaptive matching adjustments according to the size of the salinized soil molding area 16 to improve the flexibility and diversity of concrete and salinized soil molding.

[0036] like Figure 5 As shown, the internal structures of the large die body 21a, the medium die body 21b and the small die body 21c are the same, all of which are hollow structures, and a water seepage plate 25 is provided in the die body, and a water seepage hole is provided on the water seepage plate 25, and the water seepage plate 25 divides the die body into a water storage chamber 24 and a pressing groove from top to bottom, and a pressing plate 26 is detachably installed in the pressing groove, and mounting screw holes 28 are opened on the left and right sides of the water seepage plate 25, and a mounting bolt 27 is rotatably mounted on the pressing plate 26, and the pressing plate 26 is installed in the pressing groove of the die body by the mounting bolt 27, and the pressing plates 26 at the bottom of each die body are in the same horizontal plane in the initial state. A water inlet 29 connected to the water storage chamber 24 is provided on each die body, and an operating slot 210 is provided on the large die body 21a and the medium die body 21b to expose the water inlet 29 on the internal die body. The operating slot allows the water pipe to extend into the water storage chamber 24 of the medium or small die body 21c.

[0037] When conducting a concrete durability test, the pressing plate 26 can be removed from the pressing mold body, and the pressing mold body can be controlled to move down to the surface of the salinized soil through the lifting drive member, and then water can be injected into the water storage chamber 24 through the water inlet 29. The water penetrates into the upper surface of the salinized soil through the seepage plate 25 to moisten the salinized soil, thereby approximately simulating the one-dimensional migration of water in the salinized soil.

[0038] Embodiment 3: This embodiment provides a durability test method for a salinized soil erosion environment, comprising the following steps: S1, two isosceles right triangle frames are butted together by fixing bolts to form a square test mold frame 11, and during the butt connection process, the horizontal partition 14 in the movable partition is embedded in the horizontal keyway 112 of the test mold frame; S2, embedding a set of two longitudinal partitions 12 into the vertical keyway on the test mold frame, and embedding the bottom of the longitudinal partition 12 into the horizontal keyway on the horizontal partition 14; S3, inserting a set of two transverse partitions 13 into the vertical keyway on the longitudinal partition 12, at this time, the area surrounded by the horizontal partition 14, the longitudinal partition 12 and the transverse partition 13 is the concrete specimen forming area; the outer area is the salinized soil forming area; S4. Fill the mixed target concrete into the concrete specimen molding area, demould after vibration, leveling and initial setting, and put it into the molding area again after curing in the standard curing room. The concrete specimen molding process shall be carried out in accordance with the "Standard for Test Methods for Physical and Mechanical Properties of Concrete (GB / T 50081-2019)"; S5. Prepare salinized soil samples with the target required moisture content in accordance with the Geotechnical Test Method Standard (GBT 50123-2019), calculate the required soil weight according to the volume of the salinized soil forming area and the target compaction degree, place the soil in the salinized soil forming area, and press the soil sample into the forming area through the pressing mold device 2 to form a salinized soil area with the target moisture content and compacted soil; The specific order of loading soil is: a. Move the horizontal partition 14 downward and insert it into the lower horizontal keyway, take out the longitudinal and transverse partitions 13, the longitudinal partition 12 and the concrete specimen, and fill the soil in the salinized soil forming area 5 (the space area formed before and after the horizontal partition is moved) and compact it to the target compaction degree; b. Place the longitudinal partition 12, the transverse partition 13 and the concrete specimen in their original positions above the salinized soil forming area 5; c. Remove the transverse partition 13 and fill the salinized soil forming area 2 162 and forming area 4 164 (the space area formed by the transverse partition 13 and the test mold frame) with soil; d. Remove the longitudinal partition 12 and fill the salinized soil forming area 1 161 and the forming area 3 163 (the space area formed by the longitudinal partition 12 and the test mold frame) with soil; e. At this point, the soil in the salinized soil forming area (a total of 5 areas) has been completely filled, and the soil in the salinized soil forming area 16 is compacted by the pressing mold device 2; S6. After the sample is prepared, a concrete test block simulating the salinized soil erosion environment is formed and subsequent durability tests are carried out.

[0039] In steps S1-S3, the size of the concrete test mold 1 can be adjusted by changing the position of the keyway where the movable partition is located to meet the needs of making concrete specimens of different sizes. The migration speed of salt ions in soils with different moisture contents or salt contents is different, so the erosion rate of the wrapped concrete is also different. The soil moisture content and soil salt content can be adjusted in the soil sample preparation process, thereby realizing the experimental study of the influence of salinized soils with different moisture contents or salt contents on the durability of concrete. Example

[0040] On the basis of Example 3, after the sample is made, the test mold frame can be removed, and the test piece can be sealed with a sealing bag to prevent water evaporation from changing the soil moisture content, and then placed in a constant temperature and humidity test box, and the concrete test piece can be taken out regularly for durability index measurement. If the moisture content of the salinized soil is low, the soil is difficult to stabilize after the test mold frame is removed, and the test mold frame can be kept intact for overall sealing and subsequent durability tests can be carried out.

[0041] After the specimen is made, the test mold frame is removed, the outer wall of the soil sample is wrapped with latex film, and a permeable stone is placed on the upper and lower surfaces, so that the water can only migrate through the two ends of the specimen, thereby approximately simulating the one-dimensional migration of water. In order to solve the problem of inconsistent moisture content in different areas of the specimen during the wetting and drying process, the sample is wetted in the positive and negative directions and left to stand for 1 hour. This method can control the relative error of the moisture content of each part of the sample to about 1%. After the specimen is immersed in clean water to the saturated moisture content of the soil, the specimen is taken out and placed in an oven, and dried to the lower limit of the soil moisture content. According to the standard of ASTM D4843-88, a dry-wet cycle alternation test is carried out to determine the durability changes of concrete during the dry-wet cycle erosion of salinized soil.

[0042] The freeze-thaw cycle erosion test of concrete subjected to salinized soil was carried out in a closed space. On the basis of the above-mentioned dry-wet cycle alternation test, the samples were wrapped by the inner layer of latex film and breathable stone, and then the sealed bag samples were wrapped twice, and finally placed in a sealed box to play the role of the third seal (in this case, only the temperature of the sample was exchanged, limiting the interaction between the sample and the external moisture). The freeze-thaw cycle alternation test was carried out according to the ASTM D560 / D560M-16 standard, and the freeze-thaw temperatures were set to -20℃ and 20℃, respectively, to ensure that the soil samples experienced complete frost penetration and ice and snow melting during the freeze-thaw process. After several freeze-thaw cycles, the durability index of the concrete was measured to complete the freeze-thaw cycle erosion test of concrete subjected to salinized soil.

[0043] On the basis of the above-mentioned dry-wet cycle test and freeze-thaw cycle erosion test, the simulation experiment of concrete subjected to dry-wet freeze-thaw cycle alternation was conducted in four stages: wetting-drying-freezing-thawing. In the test, the specimen was first humidified to the saturated moisture content and then began to dry. The moisture content of the specimen was reduced from the saturated moisture content to the lower limit moisture content and then continued to be humidified to near the optimal moisture content. This process is called a dry-wet cycle; the specimen was frozen at -20℃ for 12 hours at the optimal moisture content, and then placed in a 20℃ curing box for 12 hours to ensure that the ice crystals melted. This process is defined as a freeze-thaw cycle; the two cycle forms are combined to complete a dry-wet freeze-thaw alternation cycle of concrete subjected to salinized soil. After several cycles, the durability index of concrete was measured to complete the dry-wet freeze-thaw alternation cycle erosion test of concrete subjected to salinized soil.

[0044] The above description is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A concrete test mold for salinized soil erosion environment, characterized in that: The concrete test mold comprises a concrete test mold, a die pressing device and a bracket, wherein the die pressing device is connected to the bottom of the bracket through a lifting drive member, and the concrete test mold is directly below the die pressing device. The concrete test mold is composed of a test mold frame and a movable partition, wherein the movable partition comprises a group of longitudinal partitions, a group of transverse partitions and a horizontal partition, and the inner walls of the test mold frame and the movable partition are provided with a plurality of key slots in the transverse and longitudinal directions, and the longitudinal partitions, the transverse partitions and the horizontal partitions can be snapped into the key slots and cooperate with the test mold frame to form concrete molding areas and saline soil molding areas of different sizes; The die pressing device comprises a die pressing group, which is composed of a large die pressing body, a medium die pressing body and a small die pressing body which are sequentially mounted. The size of the die pressing group matches the surface size of the salinized soil molding area and is used to evenly apply static pressure during the salinized soil molding process. A pressure column group is vertically arranged above each die pressing body. Each pressure column of the pressure column group is sequentially mounted and connected by limiting bolts. The outermost large pressure column is connected to the bottom of the bracket by a lifting drive member. The internal structures of the large die body, the medium die body and the small die body are the same, all of which are hollow structures, and a water seepage plate is arranged inside the die body, which divides the die body into a water storage cavity and a pressing groove up and down. A pressing plate is detachably installed in the pressing groove, and the pressing plates at the bottom of each die body are in the same horizontal plane in the initial state.

2. A concrete test mold for salinized soil erosion environment according to claim 1, characterized in that: The test mold frame is composed of two isosceles right triangle structures of the same size, which can be combined to form a square test mold frame. The inner wall of the test mold frame is provided with multiple groups of horizontal key grooves and vertical key grooves. The key groove width matches the thickness of the partition. The horizontal key grooves on the test mold frame are used to fix and adjust the position of the horizontal partition, and the vertical key grooves are used to fix and adjust the position of the longitudinal partition. The inner wall of the longitudinal partition is also provided with vertical key grooves for fixing and adjusting the position of the transverse partition.

3. A concrete test mold for salinized soil erosion environment according to claim 2, characterized in that: The movable partition and the test mold frame can cooperate to form three salinized soil forming areas of different sizes, namely a large forming area, a medium forming area and a small forming area, and the concrete forming area can be adaptively changed according to the size of the salinized soil forming area.

4. A concrete test mold for salinized soil erosion environment according to claim 1, characterized in that: A large pressure column, a medium pressure column and a small pressure column are vertically arranged above the large pressure die body, the medium pressure die body and the small pressure die body respectively. The small pressure column is longitudinally movably mounted in the medium pressure column, and the medium pressure column is longitudinally movably mounted in the large pressure column. Limiting rings are arranged in the medium pressure column and the large pressure column for limiting the internal pressure columns.

5. A concrete test mold for salinized soil erosion environment according to claim 1, characterized in that: The water seepage plate is provided with mounting screw holes on the left and right sides, and the pressing plate is rotatably sleeved with mounting bolts, and the pressing plate is installed in the pressing groove of the pressing mold body through the mounting bolts.

6. A concrete test mold for salinized soil erosion environment according to claim 1, characterized in that: Bolt fixing holes are arranged at the two isosceles right triangle interfaces of the test mold frame for fixing the test mold frame.

7. A concrete test mold for salinized soil erosion environment according to claim 1, characterized in that: Each die body is provided with a water inlet communicated with the water storage cavity, and the large die body and the medium die body are provided with an operation slot for exposing the water inlet on the inner die body.

8. A durability test method for salinized soil erosion environment, characterized in that: The following steps are involved: S1. Two isosceles right triangle frames are butt-jointed by fixing bolts to form a square test mold frame. During the butt-jointing process, the horizontal partition in the movable partition is embedded into the horizontal keyway of the test mold frame; S2, embed a set of two longitudinal partitions into the vertical keyway on the test mold frame, and embed the bottom of the longitudinal partition into the horizontal keyway on the horizontal partition; S3, insert a set of two transverse partitions into the vertical keyway on the longitudinal partition. At this time, the area surrounded by the horizontal partition, the longitudinal partition and the transverse partition is the concrete specimen forming area; the outer area is the salinized soil forming area; S4, fill the mixed target concrete into the concrete specimen molding area, demould after vibration, leveling, and initial setting, and put it into the molding area again after curing in the standard curing room; S5. Prepare a salinized soil sample with a target required moisture content, calculate the required soil weight according to the volume of the salinized soil forming area and the target compaction degree, place the soil in the salinized soil forming area, and press the soil sample into the forming area through a pressing mold device to form a salinized soil area with a target moisture content and compacted soil; S6. After the sample is prepared, a concrete test block simulating the salinized soil erosion environment is formed and subsequent durability tests are carried out.

9. A durability test method for salinized soil erosion environment according to claim 8, characterized in that: In steps S1-S3, the size of the concrete test mold can be adjusted by changing the position of the keyway where the movable partition is located to meet the needs of making concrete specimens of different sizes.

10. A durability test method for salinized soil erosion environment according to claim 8, characterized in that: After the specimen is made, the test mold frame is removed, the outer wall of the soil sample is wrapped with latex film, and a permeable stone is placed on the upper and lower surfaces to control the migration of moisture only through the two ends of the specimen, approximately simulating the one-dimensional migration of moisture. After the specimen is immersed in clean water to the saturated moisture content of the soil, the specimen is taken out and placed in an oven to dry to the lower limit of the soil moisture content. According to the ASTM D4843-88 standard, a dry-wet cycle alternating test is carried out to determine the durability changes of concrete during the dry-wet cycle erosion of salinized soil.

11. A durability test method for salinized soil erosion environment according to claim 10, characterized in that: The freeze-thaw cycle erosion test of concrete subjected to salinized soil is carried out in a closed space. On the basis of the above, the sample is wrapped by an inner layer of latex film and breathable stone, and then the sealed bag sample is wrapped for a second time, and finally placed in a sealed box for the third sealing. The freeze-thaw cycle alternation test is carried out according to the ASTM D560 / D560M-16 standard. The durability index of the concrete is determined after several freeze-thaw cycles to complete the freeze-thaw cycle erosion test of concrete subjected to salinized soil.

12. A durability test method for salinized soil erosion environment according to claim 11, characterized in that: On the basis of the above tests, the simulation experiment of concrete being subjected to alternating dry-wet freeze-thaw cycles was carried out indoors in four stages of wetting-drying-freezing-thawing. After several cycles, the durability index of concrete was measured to complete the concrete erosion test subjected to alternating dry-wet freeze-thaw cycles in salinized soil.

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