Experimental device and evaluation method for simulating suspended load abrasion of mortar and concrete

Abstract

The invention discloses an experimental device and evaluation method for simulating suspended load impact and abrasion mortar and concrete, comprising a bracket, a specimen table and a suspended load impact and abrasion assembly; the bracket comprises a base, a column and a crossbeam; the specimen table is used to fix the specimen to be simulated; one of the sidewalls of the specimen is the side to be simulated for impact and abrasion; the suspended load impact and abrasion assembly comprises a swing arm, a swing arm driving mechanism, a suspended load impact and abrasion block and a displacement detection component; the side of the suspended load impact and abrasion block facing the specimen is a suspended load impact and abrasion surface, and a plurality of rigid wear-resistant balls with a diameter not exceeding 5 mm are uniformly distributed on the suspended load impact and abrasion surface; when the suspended load impact and abrasion block swings to the lowest point, the rigid wear-resistant balls on the suspended load impact and abrasion surface can impact and abrade the side of the specimen to be simulated for impact and abrasion; the displacement detection component comprises a displacement sensor and a displacement meter. The invention evaluates the suspended load impact and abrasion mortar and concrete surface from the perspective of energy, which is helpful to reveal the mechanism of impact and abrasion, and better guide the impact and abrasion resistance design of hydraulic concrete structure.

Description

Technical Field

[0001] The invention relates to the field of building materials, in particular to an experimental device and an evaluation method for simulating suspended matter impacting mortar and concrete. Background Art

[0002] Hydraulic structures, such as dams, ship locks, flood discharge structures, power station buildings, etc., are in contact with environmental water for a long time. The flow surface is eroded and worn by suspended sediment, bedload and high-speed water flow, which places high requirements on the concrete's anti-abrasion. In addition, the concrete of the pier structure of cross-river and sea bridges is also facing erosion and wear. There are mainly two types of abrasive media in the water flow, namely bedload and suspended sediment. Rocks and sand with a particle size greater than 5mm that move near the riverbed surface by sliding, rolling, jumping or layering are bedload. Sediment with a particle size of less than or equal to 5mm suspended in the water flow and moving with the water flow is suspended sediment.

[0003] Ensuring the safety of bridges across rivers and seas is of great significance. At present, the main test methods for the scouring and wear of suspended sediment on concrete are the ring method, the wind and sand gun method and the water and sand wear machine test method. However, the instruments and equipment used in these three test methods have serious wear and tear problems during the test process, and the evaluation basis is relatively single, all of which are the mass loss of the specimen, which cannot be linked to other physical and mechanical properties of the specimen, and cannot organically combine the effect of external force with the anti-scouring and wear performance of the specimen from the perspective of energy. The mechanical properties of concrete reflect the bearing capacity, and the degree of damage to the internal structure of concrete not only determines the mechanical properties, but is also closely related to its durability and structural safety. Summary of the invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and to provide an experimental device and an evaluation method for simulating the suspended load abrasion mortar and concrete. The experimental device and the evaluation method for simulating the suspended load abrasion mortar and concrete evaluate the suspended load abrasion mortar and concrete surface from an energy perspective, which helps to reveal the mechanism of abrasion and better guide the abrasion-resistant design of hydraulic concrete structures.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] The invention discloses an experimental device for simulating suspended matter impacting mortar and concrete, comprising a bracket, a test piece table and a suspended matter impacting and impacting component.

[0007] The bracket includes a base, columns and a crossbeam; the columns are installed on both sides of the base, and the crossbeam is installed on the top of the columns.

[0008] The test piece table is arranged on a base located on one side of the crossbeam and is used to fix the test piece to be simulated; one of the side wall surfaces of the test piece is the side surface to be simulated for punching and grinding.

[0009] The suspended mass impacting and grinding assembly comprises a swing arm, a swing arm driving mechanism, a suspended mass impacting and grinding block and a displacement detection component.

[0010] The top of the swing arm is hinged to the middle of the cross beam and can swing around the cross beam and lock the angle under the drive of the swing arm driving mechanism.

[0011] The suspended matter impact and grinding block is arranged at the bottom of the swing arm and swings synchronously with the swing arm.

[0012] The side of the suspended sediment abrasion block facing the specimen is the suspended sediment abrasion surface, on which a number of rigid wear-resistant balls are evenly distributed, and the diameter of each rigid wear-resistant ball does not exceed 5 mm.

[0013] When the suspended sediment abrasion block swings to the lowest point, the rigid wear-resistant balls on the suspended sediment abrasion surface can abrade against the side surface of the specimen to be simulated abraded.

[0014] The displacement detection component comprises a displacement sensor and a displacement meter connected to the displacement sensor; the displacement sensor is arranged on the suspended load impact and grinding block and can monitor the height of the suspended load impact and grinding block.

[0015] The specimens are mortar specimens or concrete specimens.

[0016] The specimen table includes a specimen placement base and a specimen clamping piece; the specimen placement base is used to place the specimen to be simulated, and the specimen clamping piece is used to clamp the specimen placed on the specimen placement base.

[0017] The suspended matter impact and grinding assembly also includes a speed sensor connected to the swing arm driving mechanism, and the speed sensor can monitor the swing speed of the swing arm in real time.

[0018] The diameters of all rigid wear-resistant balls evenly distributed on the suspended sediment abrasion surface are the same, which is 3 mm, and the exposed height of each rigid wear-resistant ball on the suspended sediment abrasion surface is equal.

[0019] There are contact points between two adjacent rigid wear-resistant balls, so that the rigid wear-resistant balls can reach the maximum packing density on the suspended sediment abrasion surface.

[0020] The swing arm driving mechanism is a servo motor, and the motor output shaft of the servo motor has a locking function.

[0021] An experimental evaluation method for simulating suspended matter abrasion of mortar and concrete comprises the following steps.

[0022] Step 1: Prepare specimens of set specifications and cure them to the designed age.

[0023] Step 2: Saturation of specimens: Place the specimens that have been cured to the design age in a water pool until they are saturated with water.

[0024] Step 3, fix the specimen: take the specimen out of the water pool, wipe the surface of the specimen until it is saturated and dry, weigh it, and obtain the initial mass m0 of the specimen; then, place the weighed specimen on the specimen table and fix it.

[0025] Step 4, the abrasive block reaches the designed height: the swing arm, driven by the swing arm driving mechanism, drives the suspended load abrasive block to swing upward in the direction away from the test piece; the displacement detection component detects the height of the suspended load abrasive block in real time, and when the height of the suspended load abrasive block reaches the designed height H, the swing arm driving mechanism locks the swing arm; at this time, the speed sensor is started and reset to zero;

[0026] Step 5: The first suspended solid grinding includes the following steps:

[0027] Step 51, the height of the abrasive block is lowered: the swing arm is released from the designed height of step 4, and drives the suspended load abrasive block to swing downward toward the test piece in a free fall manner; during the downward swing of the suspended load abrasive block, the displacement detection component will monitor the height of the suspended load abrasive block in real time; the speed sensor will monitor the swing speed of the swing arm in real time.

[0028] Step 52, the first suspended sediment abrasion: when the suspended sediment abrasion block swings downward to the lowest point, the rigid wear-resistant balls on the suspended sediment abrasion surface will abrade against the side of the specimen to be simulated abraded; at this time, the displacement detection component will detect that the height of the suspended sediment abrasion block is zero or the lowest height; the speed sensor will detect that the swing arm has the maximum swing speed.

[0029] Step 53, detecting the rebound height: after the specimen is punched and ground, the suspended load punching and grinding block rebounds in the opposite direction; during the rebound process, the speed sensor continues to monitor the swing speed of the swing arm in real time; when the speed sensor detects that the swing speed of the swing arm is zero, the swing arm drive mechanism locks the swing arm position, and the displacement detection component detects and records the rebound height H1 of the suspended load punching and grinding block at this time.

[0030] Step 6: Repeat steps 4 and 5 until the designed number of punching and grinding times N is reached, and record the rebound height H2, H3, ..., H N ; where N≥6.

[0031] Step 7: Calculate the total impact and grinding energy E of the specimen: Based on the mass of the swing arm and the suspended solid impact and grinding block, the design height H, and the rebound heights H1, H2, H3, ..., H N , calculate the total impact and grinding energy E.

[0032] Step 8: Test piece testing. The specific testing method includes the following steps:

[0033] Step 81, observe the appearance integrity of the specimen: stop the punching and grinding test, take out the specimen from the specimen table, and inspect the appearance integrity and surface cracks of the specimen surface. The surface cracks are preferably measured by a crack width gauge to measure the size and number of surface cracks.

[0034] Step 82, internal crack detection: Use internal damage detection equipment to detect the number and size of internal cracks in the specimen after punching and grinding. The internal damage detection equipment is preferably a concrete structure CT scanner, which scans parallel to and perpendicular to the punching and grinding surface to analyze the number and size of cracks in the image.

[0035] Step 83, physical and mechanical properties testing: the compressive strength and splitting tensile strength of the punched and ground specimens are tested.

[0036] Step 9, punching and grinding performance evaluation: according to the purpose to be evaluated, combined with the total punching and grinding energy E of the specimen obtained in step 7 and the specimen test results in step 8, the punching and grinding performance evaluation is performed.

[0037] In step 9, the objectives to be evaluated include guiding the development of new impact-resistant and wear-resistant materials, durability evaluation of materials subjected to stress, and durability evaluation of materials subjected to tensile stress.

[0038] Step 91: When the purpose of the evaluation is to evaluate the durability of materials that bear stress, the evaluation index is the percentage reduction of the compressive strength per unit impact energy f cu,loss , the specific calculation method is:

[0039]

[0040] Among them, f cu,0 is the initial compressive strength of the dry specimen of the saturated surface in step 3; f′ cu is the compressive strength of the specimen after punching and grinding in step 83.

[0041] Step 92: When the purpose of the evaluation is the durability evaluation of the material bearing tensile stress, the evaluation index is the percentage reduction of the splitting tensile strength per unit impact and abrasion energy f ts,loss , the specific calculation method is:

[0042]

[0043] Among them, f ts,0 is the initial splitting tensile strength of the dry specimen of the saturated surface in step 3; f′ ts It is the splitting tensile strength of the specimen after punching and grinding in step 83.

[0044] Step 93: When the purpose of the evaluation is to guide the development of new impact-resistant and wear-resistant materials, the evaluation index needs to be determined based on the test results of the specimen appearance integrity test in step 81.

[0045] Step 93A: When the specimen has an incomplete appearance and has peeling or wear grooves on its surface, the evaluation index is the average adhesion work W and the unit wear energy mass loss m. loss .

[0046]

[0047] m=m0-m1

[0048] Wherein, S is the total area of ​​the detached or punched groove; m is the total mass loss; and m1 is the mass of the specimen after punching and grinding in step 81.

[0049] Step 93B, when the specimen has a complete appearance and there is no peeling or grinding groove on the surface of the specimen, the evaluation index is the total length of cracks L per unit grinding energy and unit area, the maximum width of cracks d per unit grinding energy and unit area, and the number of cracks n per unit grinding energy and unit area. The specific calculation formulas are:

[0050]

[0051] Among them, S 上表面 It is the area of ​​the suspended sediment abrasion surface in the specimen.

[0052] L 表 and L 内 are the total length of surface cracks and the total length of internal cracks, respectively.

[0053] d 表 and d 内 They are the maximum width of surface cracks and the maximum width of internal cracks, respectively.

[0054] n 表 and n 内 are the number of surface cracks and the number of internal cracks, respectively.

[0055] In step 6, N=10.

[0056] The present invention has the following beneficial effects:

[0057] 1. The experimental device of the present invention is simple and has little wear and tear. For example, in the wind sand gun method, the nozzle is easily damaged, and sand needs to be continuously added to the sand adding device during the test to maintain the total amount of sand.

[0058] 2. The evaluation method is more scientific and reasonable. In addition to using the mass loss of the specimen as the basis for evaluation, the present invention also adds energy as a basis, and organically links the abrasion energy of the specimen with the mechanical properties (residual strength), defect characteristics (cracks) and material structure characteristics (interface properties) of the specimen. The structure of the material determines the properties of the material. The properties are the external reflection of the structure and have a decisive influence on the performance of the material. After the energy is introduced, the mechanical properties, specimen structure and defect characteristics of the specimen after abrasion are linked. Compared with the use of a single mass loss as the basis for evaluation, the evaluation method used in the present invention is more reasonable. In addition, since the surface tension of mortar and concrete is not only anisotropic, the surface free energy in different regions is also different. The surface tension and surface free energy of the protrusions on the solid surface are greater than those of the depressions. The force between the various phases of cement mortar and concrete is generated by the interaction between the surface force field of each phase and the surface force field of the adjacent phase. Abrasion is external energy input to destroy the interface force. Therefore, the present invention evaluates the suspended sediment abrasion of mortar and concrete surface from the perspective of energy, which helps to reveal the mechanism of abrasion and better guide the abrasion-resistant design of hydraulic concrete structures.

[0059] 3. The experimental device of the present invention can also evaluate the abrasion resistance of constrained mortar and concrete specimens in actual working conditions, and is particularly suitable for evaluating the abrasion resistance of concrete of pressure-bearing structures such as bridge piers.

[0060] 4. The present invention can simulate the impact of water velocity, flow rate, suspended sediment specifications and quantity on mortar and concrete. According to the suspended sediment specifications, the diameter of the rigid wear-resistant hemisphere is adjusted. The smaller the average particle size of the suspended sediment, the smaller the diameter of the rigid wear-resistant hemisphere; the smaller the number of suspended sediment, the fewer rigid wear-resistant hemispheres on the impact surface; the faster the water velocity and the larger the flow rate, the greater the mass of the suspended sediment impact block. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 The schematic diagram of the structure of an experimental device for simulating suspended matter abrasion of mortar and concrete according to the present invention is shown.

[0062] Figure 2 Shows Figure 1 Left side view.

[0063] Figure 3 The schematic diagram of the structure of the suspended sediment abrasive surface in the present invention is shown.

[0064] Figure 4 Shows Figure 1 Top view of the .

[0065] Figure 5 A schematic diagram of the structure of the test piece in the present invention is shown.

[0066] Figure 6A schematic diagram showing a preferred structure of the specimen clamping member of the present invention is shown.

[0067] Figure 7 Schematic diagram showing the average adhesion work W and interfacial tension of aggregate and gel in concrete specimens.

[0068] Among them are:

[0069] 11. Column; 12. Beam; 13. Base;

[0070] 21. Swing arm; 22. Suspended sediment abrasive block; 23. Suspended sediment abrasive surface;

[0071] 31. Specimen placing base; 32. Specimen clamping piece; 321. Pressing plate; 322. Screw;

[0072] 40. Specimen; 41. Aggregate; 42. Gel;

[0073] 4. Displacement detection component; 5. Speed ​​sensor; 6. Servo motor. DETAILED DESCRIPTION

[0074] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific preferred embodiments.

[0075] In the description of the present invention, it should be understood that the terms "left side", "right side", "upper part", "lower part" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. "First", "second" and the like do not indicate the importance of the components, and therefore cannot be understood as limiting the present invention. The specific dimensions used in this embodiment are only for illustrating the technical solution, and do not limit the scope of protection of the present invention.

[0076] like Figure 1 and Figure 4 As shown, an experimental device for simulating suspended load abrasion of mortar and concrete includes a bracket, a specimen table and a suspended load abrasion component.

[0077] like Figure 2 As shown, the bracket includes a base 13, a column 11 and a crossbeam 12; the columns are installed on both sides of the base, and the crossbeam is installed on the top of the columns.

[0078] The test piece table is arranged on a base located on one side of the crossbeam and is used for fixing the test piece to be simulated.

[0079] like Figure 4 As shown, the specimen table includes a specimen placement base 31 and a specimen clamping member 32 .

[0080] The above-mentioned test piece placement base is used to place Figure 5 The specimen 40 to be simulated is shown. The specimen is preferably a square with a side length of a, and the specimen can be a mortar specimen or a concrete specimen. One of the side walls of the specimen is the side surface to be simulated for impact grinding.

[0081] The specimen clamp is used to clamp the specimen placed on the specimen placement base. The preferred structure is as follows: Figure 6 As shown, it includes two parallel pressing plates 321 and four screws 322 connecting the two pressing plates. The four screws are preferably arranged in a square at the four corners of the two pressing plates, and the nuts are tightened by a torque wrench to give the specimen compressive stress. The distance between two adjacent screws is b, then b>a, so as to ensure that the suspended sediment impact and grinding block does not contact the screws.

[0082] The suspended matter impact and grinding assembly includes a swing arm 21 , a swing arm driving mechanism, a suspended matter impact and grinding block 22 , a displacement detection component 4 and a speed sensor 5 .

[0083] The top of the swing arm is hinged to the middle of the beam and can swing around the beam and lock the angle under the drive of the swing arm drive mechanism. The length of the swing arm can be adjusted according to the actual working conditions to be simulated.

[0084] The swing arm driving mechanism is preferably a servo motor 6, and the motor output shaft of the servo motor has a locking function.

[0085] The suspended matter impact and grinding block (also referred to as the impact and grinding block) is arranged at the bottom of the swing arm and swings synchronously with the swing arm.

[0086] The side of the suspended solid impact block facing the specimen is as follows Figure 3 The suspended sediment abrasion surface 23 (also referred to as abrasion surface) shown is evenly distributed with a plurality of rigid wear-resistant balls, each of which has a diameter of no more than 5 mm, so as to simulate suspended sediment.

[0087] In this embodiment, the diameters of all rigid wear-resistant balls uniformly distributed on the suspended sediment abrasion surface are the same, preferably 3 mm, so as to simulate the abrasion effect of medium-sized suspended sediment particles on the specimen. The diameter of the rigid wear-resistant hemisphere is adjusted according to the suspended sediment specifications. The smaller the average particle size of the suspended sediment, the smaller the diameter of the rigid wear-resistant hemisphere; the smaller the amount of suspended sediment, the fewer rigid wear-resistant hemispheres on the abrasion surface can be; the faster the water flow speed and the larger the flow rate, the greater the mass of the suspended sediment abrasion block.

[0088] In this embodiment, there are contact points between two adjacent rigid wear-resistant balls, so that the rigid wear-resistant hemispheres 24 are evenly distributed on the surface of the abrasive surface 23 in the most densely packed manner, simulating a maximum amount of suspended matter abrasive specimens.

[0089] Furthermore, the exposed height of each rigid wear-resistant ball on the suspended sediment abrasion surface is equal, that is, the top surfaces (highest points) of all rigid wear-resistant balls are located on the same horizontal plane.

[0090] When the suspended sediment abrasion block swings to the lowest point, the rigid wear-resistant balls on the suspended sediment abrasion surface can abrade against the side surface of the specimen to be simulated abraded.

[0091] The displacement detection component comprises a displacement sensor and a displacement meter connected to the displacement sensor; the displacement sensor is arranged on the suspended load impact and abrasion block and can monitor the height of the suspended load impact and abrasion block.

[0092] The speed sensor can monitor the swing speed of the swing arm in real time.

[0093] An experimental evaluation method for simulating suspended matter abrasion of mortar and concrete comprises the following steps.

[0094] Step 1: Prepare specimens of set specifications and cure them to the designed age.

[0095] Among them, the preferred specifications of mortar specimens are 40×40×160mm prisms and 70.7×70.7×70.7mm cubes; the preferred specifications of concrete specimens are 150×150×150mm cubes, 100×100×100mm cubes, 200×200×200mm cubes, 150×150×300mm prisms, and 100×100×300mm prisms. Curing to the design age.

[0096] Step 2: Saturate the specimen with water: Place the specimen that has been cured to the design age in a water pool at 20℃±1℃ and saturate it with water.

[0097] Step 3, fix the specimen: take the specimen out of the water pool, wipe the surface of the specimen until it is saturated and dry, weigh it, and obtain the initial mass m0 of the specimen; then, place the weighed specimen on the specimen table and fix it.

[0098] Step 4, the grinding block reaches the designed height: the swing arm is driven by the swing arm driving mechanism, driving the suspended load grinding block to swing upward in the direction away from the test piece; the displacement detection component detects the height of the suspended load grinding block in real time, and when the height of the suspended load grinding block reaches the designed height H, the swing arm driving mechanism locks the swing arm; at this time, the speed sensor is started and reset to zero.

[0099] In this embodiment, the design height H is preferably when the swing arm is raised to a horizontal height, that is, Figure 1 The center pointer is at 3 o'clock.

[0100] Step 5: The first suspended solid grinding comprises the following steps.

[0101] Step 51, the height of the abrasive block is lowered: the swing arm is released from the designed height of step 4, and drives the suspended load abrasive block to swing downward toward the test piece in a free fall manner; during the downward swing of the suspended load abrasive block, the displacement detection component will monitor the height of the suspended load abrasive block in real time; the speed sensor will monitor the swing speed of the swing arm in real time.

[0102] Step 52, first suspended sediment abrasion: When the suspended sediment abrasion block swings downward to the lowest point (i.e. Figure 1 When the pointer in the middle is at the position of 6 o'clock, the rigid wear-resistant balls on the suspended sediment abrasion surface will abrade against the side of the specimen to be simulated abrasion; at this time, the displacement detection component will detect that the height of the suspended sediment abrasion block is zero or the lowest height; the speed sensor will detect that the swing arm has the maximum swing speed.

[0103] Step 53, detecting the rebound height: after the specimen is punched and ground, the suspended load punching and grinding block rebounds in the opposite direction; during the rebound process, the speed sensor continues to monitor the swing speed of the swing arm in real time; when the speed sensor detects that the swing speed of the swing arm is zero, the swing arm drive mechanism locks the swing arm position, and the displacement detection component detects and records the rebound height H1 of the suspended load punching and grinding block at this time.

[0104] Step 6: Repeat steps 4 and 5 until the designed number of punching and grinding times N is reached, and record the rebound height H2, H3, ..., H N ; Among them, N≥6, and in this embodiment, N=10 is preferred.

[0105] Step 7: Calculate the total impact and grinding energy E of the specimen: Based on the mass of the swing arm and the suspended solid impact and grinding block, the design height H, and the rebound heights H1, H2, H3, ..., H N , calculate the total impact and grinding energy E.

[0106] Step 8: Test piece testing. The specific testing method includes the following steps.

[0107] Step 81, observe the appearance integrity of the specimen: stop the impact and grinding test, take out the specimen from the specimen table, and inspect the appearance integrity and surface cracks of the specimen surface.

[0108] Step 82, internal crack detection: use internal damage detection equipment to detect the number and size of internal cracks in the specimen after punching and grinding.

[0109] Step 83, physical and mechanical properties testing: the compressive strength and splitting tensile strength of the punched and ground specimens are tested.

[0110] Step 9, punching and grinding performance evaluation: according to the purpose to be evaluated, combined with the total punching and grinding energy E of the specimen obtained in step 7 and the specimen test results in step 8, the punching and grinding performance evaluation is performed.

[0111] In step 9, the objectives to be evaluated include guiding the development of new impact-resistant and wear-resistant materials, durability evaluation of materials subjected to stress, and durability evaluation of materials subjected to tensile stress.

[0112] Step 91: When the purpose of the evaluation is to evaluate the durability of materials that bear stress, the evaluation index is the percentage reduction of the compressive strength per unit impact energy f cu,loss , the specific calculation method is:

[0113]

[0114] Among them, f cu,0 is the initial compressive strength of the dry specimen of the saturated surface in step 3; f′ cu is the compressive strength of the specimen after punching and grinding in step 83. cu,loss The lower the better. When the value is higher than the minimum design requirement, it indicates that the material is not suitable for use in the design environment.

[0115] Step 92: When the purpose of the evaluation is the durability evaluation of the material bearing tensile stress, the evaluation index is the percentage reduction of the splitting tensile strength per unit impact and abrasion energy f ts,loss , the specific calculation method is:

[0116]

[0117] Among them, f ts,0 is the initial splitting tensile strength of the dry specimen of the saturated surface in step 3; f′ ts is the splitting tensile strength of the specimen after punching and grinding in step 83. ts,loss The lower the better. When the value is higher than the minimum design requirement, it indicates that the material is not suitable for use in the design environment.

[0118] Step 93: When the purpose of the evaluation is to guide the development of new impact-resistant and wear-resistant materials, the evaluation index needs to be determined based on the test results of the specimen appearance integrity test in step 81.

[0119] Step 93A: When the specimen has an incomplete appearance and has peeling or wear grooves on its surface, the evaluation index is the average adhesion work W and the unit wear energy mass loss m. loss .

[0120]

[0121] m=m0-m1

[0122] Wherein, S is the total area of ​​the detached or punched groove; m is the total mass loss; and m1 is the mass of the specimen after punching and grinding in step 81.

[0123] The higher the average adhesion work W, the better. If the value is low, technical means can be used to enhance the interface performance and improve the average adhesion work, thereby improving the material's anti-wear performance.

[0124] The above unit impact and abrasion energy mass loss m loss The lower the better. Together with the average adhesion work W, it is suitable for guiding the development of new anti-wear materials. If the value is high, the interface performance can be enhanced through technical means to reduce the value of this indicator. Unit impact energy mass loss m loss It is a macroscopic reflection of the average adhesion work W, which characterizes the anti-wear performance of the material from the internal microstructure of the material.

[0125] Step 93B, when the specimen has a complete appearance and there is no peeling or grinding groove on the surface of the specimen, the evaluation index is the total length of cracks L per unit grinding energy and unit area, the maximum width of cracks d per unit grinding energy and unit area, and the number of cracks n per unit grinding energy and unit area. The specific calculation formulas are:

[0126]

[0127] Among them, S 上表面 It is the area of ​​the suspended sediment abrasion surface in the specimen.

[0128] L 表 and L 内 are the total length of surface cracks and the total length of internal cracks, respectively.

[0129] d 表 and d 内 They are the maximum width of surface cracks and the maximum width of internal cracks, respectively.

[0130] n 表 and n 内 are the number of surface cracks and the number of internal cracks, respectively.

[0131] The lower the above three indicators L, d and n, the better. When the indicator d is higher than the allowable value, it indicates that the material has poor anti-wear performance. When the indicator d is within the allowable value and the indicator n exceeds the allowable value, it indicates that the material has poor anti-wear performance. When the indicators d and n are both within the allowable value, the indicator L is high, and the anti-wear performance is poor.

[0132] In addition to using the mass loss of the specimen as the basis for evaluation, the present invention also adds energy as a basis, organically linking the grinding energy of the specimen with the mechanical properties (residual strength), defect characteristics (cracks) and material structure characteristics (interface properties) of the specimen. The structure of the material determines the properties of the material, and the properties are the external reflection of the structure and have a decisive influence on the performance of the material. After the energy is introduced, the mechanical properties, specimen structure and defect characteristics of the specimen after the grinding are linked together. Compared with the use of a single mass loss as the basis for evaluation, the evaluation method used by the present invention is more reasonable.

[0133] The concrete in the concrete specimen is a three-phase composite material of solid, liquid and gas, which is composed of hydration products of cementitious materials, aggregates and pores (water in the pores). Cementitious materials are the binder of aggregates. The adhesion between hydration products and aggregates is actually the result of the mutual attraction of particles under the residual force field of the solid surface. The interaction force is also called surface force, which is divided into chemical force and molecular attraction. Take the separation of aggregate and gel interface as an example. Figure 7 As shown, the adhesion work W is equal to the newly formed surface energy γ SV and γ S ' V And the difference in interfacial energy γ between the disappeared aggregate and the gel is shown in the following formula, thereby organically linking the energy (the impact and abrasion energy E of the specimen) with its interfacial performance.

[0134] W = γ SV +γ S ' V -γ

[0135] By observing the surface morphology of the specimen and using graphic analysis software, it is very convenient to obtain the area of ​​the specimen wear after punching and grinding, and then combined with the punching and grinding energy, the average adhesion work of the specimen can be obtained. The interface performance of the material can be further analyzed based on the above formula.

[0136] Concrete is a brittle material. The theoretical strength of brittle materials is several hundred times the actual strength. The microcracks inside the material act as a stress multiplier. Griffith theory gives the relationship between the actual fracture strength and the length of the microcracks, as shown in the following formula. The residual strength (actual strength) of the specimen after impact and abrasion can be linked to the internal microcracks of the specimen after impact and abrasion through the following formula.

[0137]

[0138] Where: R——breaking strength;

[0139] C——internal microcrack length;

[0140] E0——elastic modulus;

[0141] a——Surface free energy.

[0142] According to the above formula, the change in the length of microcracks inside the specimen after punching and grinding can be analyzed.

[0143] The preferred embodiments of the present invention are described in detail above; however, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. An experimental device for simulating suspended matter abrasion of mortar and concrete, characterized in that: It includes a bracket, a specimen table and a suspended matter impact and grinding assembly; The bracket includes a base, a column and a beam; the columns are installed on both sides of the base, and the beam is installed on the top of the column; The test piece table is arranged on a base located on one side of the crossbeam, and is used to fix the test piece to be simulated; one of the side walls of the test piece is the side surface to be simulated for punching and grinding; The suspended mass impacting and grinding assembly comprises a swing arm, a swing arm driving mechanism, a suspended mass impacting and grinding block and a displacement detection component; The top of the swing arm is hinged to the middle of the cross beam, and can swing around the cross beam and lock the angle under the drive of the swing arm driving mechanism; The suspended sediment impact and grinding block is arranged at the bottom of the swing arm and swings synchronously with the swing arm; The side of the suspended sediment abrasion block facing the specimen is the suspended sediment abrasion surface, on which a number of rigid wear-resistant balls are evenly distributed, and the diameter of each rigid wear-resistant ball does not exceed 5mm; When the suspended sediment abrasion block swings to the lowest point, the rigid wear-resistant balls on the suspended sediment abrasion surface can abrade against the side surface of the specimen to be simulated abrasion; The displacement detection component comprises a displacement sensor and a displacement meter connected to the displacement sensor; the displacement sensor is arranged on the suspended load impact and grinding block and can monitor the height of the suspended load impact and grinding block.

2. The experimental device for simulating suspended matter abrasion of mortar and concrete according to claim 1, characterized in that: The specimens are mortar specimens or concrete specimens.

3. The experimental device for simulating suspended matter abrasion of mortar and concrete according to claim 1, characterized in that: The specimen table includes a specimen placement base and a specimen clamping piece; the specimen placement base is used to place the specimen to be simulated, and the specimen clamping piece is used to clamp the specimen placed on the specimen placement base.

4. The experimental device for simulating suspended matter abrasion of mortar and concrete according to claim 1, characterized in that: The suspended matter impact and grinding assembly also includes a speed sensor connected to the swing arm driving mechanism, and the speed sensor can monitor the swing speed of the swing arm in real time.

5. The experimental device for simulating suspended matter abrasion of mortar and concrete according to claim 1, characterized in that: The diameters of all rigid wear-resistant balls evenly distributed on the suspended sediment abrasion surface are the same, which is 3 mm, and the exposed height of each rigid wear-resistant ball on the suspended sediment abrasion surface is equal.

6. The experimental device for simulating suspended matter abrasion of mortar and concrete according to claim 5, characterized in that: There are contact points between two adjacent rigid wear-resistant balls, so that the rigid wear-resistant balls can reach the maximum packing density on the suspended sediment abrasion surface.

7. The experimental device for simulating suspended matter abrasion of mortar and concrete according to claim 1, characterized in that: The swing arm driving mechanism is a servo motor, and the motor output shaft of the servo motor has a locking function.

8. An experimental evaluation method for simulating suspended load abrasion of mortar and concrete, based on the experimental device for simulating suspended load abrasion of mortar and concrete according to any one of claims 1 to 7, characterized in that: The steps include: Step 1: Prepare specimens of set specifications and maintain them to the designed age; Step 2: Saturation of specimens: Place the specimens that have been cured to the design age in a water pool until they are saturated with water; Step 3, fix the specimen: take the specimen out of the water pool, wipe the surface of the specimen until it is saturated and dry, weigh it, and obtain the initial mass m0 of the specimen; then, place the weighed specimen on the specimen table and fix it; Step 4, the abrasive block reaches the designed height: the swing arm, driven by the swing arm driving mechanism, drives the suspended load abrasive block to swing upward in the direction away from the test piece; the displacement detection component detects the height of the suspended load abrasive block in real time, and when the height of the suspended load abrasive block reaches the designed height H, the swing arm driving mechanism locks the swing arm; at this time, the speed sensor is started and reset to zero; Step 5: The first suspended solid grinding includes the following steps: Step 51, the height of the abrasive block is lowered: the swing arm is released from the designed height of step 4, and drives the suspended mass abrasive block to swing downward toward the test piece in a free fall manner; during the downward swing of the suspended mass abrasive block, the displacement detection component monitors the height of the suspended mass abrasive block in real time; the speed sensor monitors the swing speed of the swing arm in real time; Step 52, first suspended sediment abrasion: when the suspended sediment abrasion block swings downward to the lowest point, the rigid wear-resistant balls on the suspended sediment abrasion surface will abrade against the side surface of the specimen to be simulated abrasion; at this time, the displacement detection component will detect that the height of the suspended sediment abrasion block is zero or the lowest height; the speed sensor will detect that the swing arm has the maximum swing speed; Step 53, testing the rebound height: after the specimen is punched and ground, the suspended material punching and grinding block rebounds in the opposite direction; During the rebound process, the speed sensor continues to monitor the swing speed of the swing arm in real time; when the speed sensor detects that the swing speed of the swing arm is zero, the swing arm drive mechanism locks the swing arm position, and the displacement detection component detects and records the rebound height H1 of the suspended material impact and grinding block at this time; Step 6: Repeat steps 4 and 5 until the designed number of punching and grinding times N is reached, and record the rebound height H2, H3, ..., H N ; Among them, N ≥ 6; Step 7: Calculate the total impact and grinding energy E of the specimen: Based on the mass of the swing arm and the suspended solid impact and grinding block, the design height H, and the rebound heights H1, H2, H3, ..., H N , calculate the total impact and grinding energy E; Step 8: Test piece testing. The specific testing method includes the following steps: Step 81, observing the appearance integrity of the specimen: stop the punching and grinding test, take out the specimen from the specimen table, and inspect the appearance integrity and surface cracks of the specimen surface; Step 82, internal crack detection: using internal damage detection equipment to detect the number and size of internal cracks in the specimen after punching and grinding; Step 83, physical and mechanical properties testing: testing the compressive strength and splitting tensile strength of the punched and ground specimens; Step 9, punching and grinding performance evaluation: according to the purpose to be evaluated, combined with the total punching and grinding energy E of the specimen obtained in step 7 and the specimen test results in step 8, the punching and grinding performance evaluation is performed.

9. The experimental evaluation method for simulating suspended load abrasion of mortar and concrete according to claim 8, characterized in that: In step 9, the purposes to be evaluated include guiding the development of new impact-resistant materials, durability evaluation of materials subject to stress, and durability evaluation of materials subject to tensile stress; Step 91: When the purpose of the evaluation is to evaluate the durability of materials that bear stress, the evaluation index is the percentage reduction of the compressive strength per unit impact energy f cu,loss , the specific calculation method is: Among them, f cu,0 is the initial compressive strength of the dry specimen of the saturated surface in step 3; f′ cu is the compressive strength of the specimen after punching and grinding in step 83; Step 92: When the purpose of the evaluation is the durability evaluation of the material bearing tensile stress, the evaluation index is the percentage reduction of the splitting tensile strength per unit impact and abrasion energy f ts,loss , the specific calculation method is: Among them, f ts,0 is the initial splitting tensile strength of the dry specimen of the saturated surface in step 3; f′ ts is the splitting tensile strength of the specimen after punching and grinding in step 83; Step 93: When the purpose of the evaluation is to guide the development of new impact-resistant and wear-resistant materials, the evaluation index needs to be determined based on the test result of the specimen appearance integrity test in step 81; Step 93A: When the specimen has an incomplete appearance and has peeling or wear grooves on its surface, the evaluation index is the average adhesion work W and the unit wear energy mass loss m. loss ; m=m0-m1 Wherein, S is the total area of ​​the detached or punched groove; m is the total mass loss; m1 is the mass of the specimen after punching and grinding in step 81; Step 93B, when the specimen has a complete appearance and there is no peeling or grinding groove on the surface of the specimen, the evaluation index is the total length of cracks L per unit grinding energy and unit area, the maximum width of cracks d per unit grinding energy and unit area, and the number of cracks n per unit grinding energy and unit area. The specific calculation formulas are: Among them, S 上表面 is the area of ​​the suspended sediment abrasion surface in the specimen; L 表 and L 内 are the total length of surface cracks and the total length of internal cracks, respectively; d 表 and d 内 are the maximum width of surface cracks and the maximum width of internal cracks, respectively; n 表 and n 内 are the number of surface cracks and the number of internal cracks, respectively.

10. The experimental evaluation method for simulating suspended load abrasion of mortar and concrete according to claim 8, characterized in that: In step 6, N=10.

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