A testing model and usage method for the ion penetration depth of mortar or concrete

Abstract

The present invention provides a test model and a usage method for the ion penetration depth of mortar or concrete, including a bottom mold and a limiting top mold. The upper part of the bottom mold is inclined, and the limiting top mold is installed on the bottom mold; a number of rows of metal cylinder assemblies are inserted into the limiting top mold; the metal cylinder assembly includes a number of uniformly distributed metal cylinders; the shape of the metal cylinder is a cylinder obliquely cut with the axis, and the inclination angle of the oblique section of the metal cylinder is the same as the inclination angle of the limiting top mold. The test model and the usage method for the ion penetration depth of mortar or concrete provided by the present invention can measure the penetration depth at gradient time, save experimental time, have a simple structure and low cost, adopt the natural penetration method, are convenient for sampling and testing, and can conduct continuous experiments to obtain the penetration depth at different times, and can be widely used.

Description

Technical Field

[0001] The invention belongs to the field of building material testing, and in particular relates to a model for testing the ion penetration depth of mortar or concrete and a use method thereof. Background Art

[0002] The existing ion penetration depth test method of mortar / concrete is mainly for chloride ions. The test method is mainly the rapid chloride ion migration coefficient method (RCM method) in GB / T 50082 "Test method for long-term performance and durability of ordinary concrete", which is used to determine the migration coefficient of non-steady-state migration of chloride ions in concrete to determine the concrete's resistance to chloride ion penetration. The color development method in DL / T 5126 "Test procedures for polymer-modified cement mortar" requires splitting of the mortar test block during the test, resulting in an uneven cross section, which is inconvenient to measure with a vernier caliper. The cross section is uneven, and it is not easy to accurately locate the boundary position with a vernier caliper, which easily leads to a large measured value. CN 111077055 A discloses a method for measuring the penetration depth of chloride ions. By collecting cross-sectional images, the area of the white precipitation area and the non-white precipitation area of the color development reaction are obtained, and the average penetration depth of chloride ions is further obtained by calculation. The acquisition of cross-sectional images requires an image scanner, which has a high cost and is complicated to operate, and cannot be widely used. Summary of the invention

[0003] In view of this, the present invention aims to propose a model and method for testing the ion penetration depth of mortar or concrete, which adopts the natural penetration method, is convenient for sampling and testing, and can carry out continuous experiments to obtain the penetration depth at different times.

[0004] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0005] A model for testing the ion penetration depth of mortar or concrete, comprising a bottom mold and a limit top mold, wherein the top of the bottom mold is inclined, and the limit top mold is installed on the bottom mold;

[0006] A plurality of rows of metal cylinder components are inserted into the limiting top mold;

[0007] The metal cylinder assembly includes a plurality of evenly distributed metal cylinders;

[0008] The metal cylinder is in the shape of a cylinder obliquely cut with the axis, and the inclination angle of the oblique cut surface of the metal cylinder is the same as the inclination angle of the limiting top mold.

[0009] The two ends of the bottom mold are provided with positioning grooves, and the two ends of the limiting top mold are provided with positioning blocks that match the positioning grooves; the two ends of the limiting top mold are provided with handles;

[0010] A pull ring is arranged above the metal cylinder.

[0011] The lower end of the inclined end of the bottom mold is the thinnest part. Wax is applied to the thinnest part of the upper inclined surface as needed to ensure that the corrosive solution does not penetrate through the upper inclined surface.

[0012] The number of the metal cylinder assemblies is at least 1.

[0013] A method for using a test model for the ion penetration depth of mortar or concrete, characterized by comprising the following steps:

[0014] S1: Select the size of the test model according to the maximum aggregate size of the mortar to be tested. Add water to the mortar or concrete to be tested and stir. After stirring is completed, pour it into the model, and sequentially install the limiting top mold and the metal cylinder on the bottom mold;

[0015] S2: After forming at a certain temperature and humidity, cure for a period of time, and take out the formed mortar from the bottom mold;

[0016] S3: Wax the mortar after demolding in step S2 to obtain a test piece;

[0017] S4: Place a piece of absorbent sponge into the corrosive solution. After the sponge is completely soaked, place the test piece obtained in step S3 on the sponge;

[0018] S5: After soaking in the corrosive solution for a period of time, take the leftmost metal cylinder and perform tests sequentially to judge the penetration depth.

[0019] The corrosive solution is sulfate or chloride, such as NaCl solution, Na2SO4 solution, MgCl2 solution, and a mixed solution of various substances such as NaCl and MgCl2 in brine from a salt field in actual production.

[0020] In step S1, when selecting the size of the test model, for fine sand mortar with a maximum aggregate size of less than 2.36 mm for mortar or concrete, it is usually required that the minimum size of the mortar mold or construction part shall not be less than 1.5 times the maximum aggregate size. The present invention is divided into two types: fine sand mortar mold and coarse sand mortar mold. The smallest parts in the mold are the inner diameter D of the metal cylinder, the shortest height h, and the horizontal spacing x.

[0021] Among them, the maximum aggregate size of the fine sand mortar is less than 2.36 mm. For the convenience of forming, its size is enlarged to: the D of the corresponding mold metal cylinder is 5 mm, the h is 5 mm, and the x is 10 mm, which can all meet the requirement of ≥1.5 times the maximum aggregate size;

[0022] When the maximum aggregate size is greater than 2.36 mm for coarse sand mortar, the maximum aggregate size of the coarse sand mortar is greater than 2.36 mm. Design the D of the corresponding mold metal cylinder to be The h is x is All can meet the requirement of ≥1.5 times the maximum aggregate size.

[0023] The wall thickness δ of the metal cylinder is 0.5 mm.

[0024] Both Standard DL / T 5126 - 2001 and JG / T 337 - 2011 require a test accuracy of 1 mm. Among them, JG / T 337 - 2011 requires that the chloride ion penetration depth ≤ 7 mm, and the designed test depth is n (n ≥ 7 mm).

[0025] The calculation formula for the slope k of the upper surface of the bottom mold is:

[0026] The calculation formula for the maximum height H1 of the bottom mold is: H1 = n + h + k×(D + a), where a is the horizontal distance from the bottom metal cylinder to the shortest height of the bottom mold; the horizontal distance from the bottom metal cylinder to the shortest height of the bottom mold is the same as the horizontal distance from the top metal cylinder to the longest height of the bottom mold; is the maximum aggregate size of the mortar to be tested;

[0027] The calculation formula for the shortest height H2 of the bottom mold is: H2 = h + 1 - k×a,

[0028] The calculation formula for the length L of the bottom mold is L = (n - 1)×x + 2×a + 2×δ + D.

[0029] The specific design is:

[0030] For the fine sand mortar mold, a = 5 mm, k = 0.1, H1 = n + 6 mm, H2 = 5.5 mm, L = 10n + 6.

[0031] Coarse sand mortar mold

[0032] The curing temperature in step S2 is 20 - 30 °C, the humidity is 40 - 70%, and the curing age is 28 d.

[0033] The wax sealing method in step S3 includes the following steps:

[0034] A1: The mass ratio of rosin to paraffin is 1:2 - 3, and it is heated and melted in a metal tray and mixed evenly;

[0035] A2: Immerse the four sides of the demolded mortar into the mixed liquid obtained in step A1 for 1 - 2 mm and keep it for 1 - 5 s;

[0036] A3: Immerse the bottom end of the upper inclined plane of the demolded mortar into the mixed liquid obtained in step A1 for 1 - 5 mm, keep it for 1 - 5 s and then take it out, and the wax sealing is completed.

[0037] In step S4, the corrosion solution is placed in a water tank, and a water-absorbing sponge is put in. Wait until the sponge absorbs the corrosion emulsion to saturation, and the liquid level of the corrosion solution in the water tank is not higher than the upper surface of the sponge. Then, place the specimen on the sponge so that the bottom surface of the specimen contacts the corrosion solution through the contact surface with the sponge.

[0038] The number of metal cylinder assemblies is at least 1;

[0039] When the number of metal cylinder assemblies is one, the ion penetration depth of mortar or concrete at one time can be measured;

[0040] When the number of metal cylinder assemblies is multiple, the ion penetration depths of mortar or concrete at multiple times can be measured; the soaking time is in gradients, and the ion penetration depths of mortar or concrete at different times can be measured.

[0041] The test in step S5 includes the following steps: Take out the mortar in the cylinder through a metal pull ring, spray 0.1% fluorescein yellow indicator and 0.1N silver nitrate solution on its bottom surface. If white precipitate appears, it has penetrated to this depth. Another point can be taken for continuous testing until no white precipitate appears. The vertical distance from the bottom of the metal cylinder at the last point where white precipitate appears to the lower bottom surface is the penetration depth.

[0042] This device takes out a metal cylinder through a metal pull ring and conducts a color reaction on the bottom surface of the mortar. If white precipitate appears, it has penetrated to this depth. Another point can be taken for continuous testing until no white precipitate appears. The height from the bottom of the metal cylinder at the last point where white precipitate appears to the lower bottom surface is the penetration depth. For chloride ions, the color reaction is carried out by first spraying 0.1N silver nitrate solution and then spraying 0.1% fluorescein yellow indicator. For SO 4 2- , the cross-section can be polished by 1 mm powder for XRD scanning, and whether there are sulfate characteristic spectral lines can be judged through the XRD spectrogram.

[0043] According to the experimental needs, multiple points are arranged at the same depth position. Multi-point testing can be carried out at the same depth to make the results more accurate, which is applicable to the test of penetration depth under different corrosion times. If at a certain corrosion time at the same depth, two points have not penetrated, the corrosion time can be continued to extend, and then other points at this depth can be tested, avoiding the need to use new specimens for the experiment again and saving time.

[0044] In addition, for the mortar taken out of the cylinder after corrosion, the bottom surface can be ground into powder, and the ground powder can be subjected to energy spectrum scanning by a scanning electron microscope. Whether ions penetrate in can be determined through the energy spectrum scanning results. Energy spectrum scanning can be used to measure other ions except chloride ions. As long as they can be distinguished from the ions existing in the cement mortar itself, they can be detected. Based on this, this model can be applied to the measurement of the ion penetration depth of various corrosion solutions.

[0045] Compared with the prior art, the model and its usage method for measuring the ion penetration depth of mortar or concrete according to the present invention have the following beneficial effects:

[0046] 1. When the number of metal cylinder assemblies is multiple, the ion penetration depths of mortar or concrete at multiple times can be measured; the soaking time is in gradients, and the ion penetration depths of mortar or concrete at different times can be measured, saving experimental time. Moreover, the structure is simple and the cost is low. Using the natural penetration method, it is convenient for sampling and testing, and continuous experiments can be carried out to obtain the penetration depths at different times, and it can be widely used.

[0047] 2. If at a certain corrosion time at the same depth, there are two points that have not penetrated, the corrosion time can be continued to extend, and other points at this depth can be continuously tested, avoiding the need to use new specimens to re-conduct the experiment, saving time. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0049] Figure 1 is a schematic diagram of a model for measuring the ion penetration depth of mortar or concrete according to an embodiment of the present invention;

[0050] Figure 2 is a schematic diagram of a single metal cylinder assembly of a model for measuring the ion penetration depth of mortar or concrete according to an embodiment of the present invention;

[0051] Figure 3 is a schematic diagram of multiple metal cylinder assemblies of a model for measuring the ion penetration depth of mortar or concrete according to an embodiment of the present invention;

[0052] Figure 4 is a schematic diagram of the usage of a model for measuring the ion penetration depth of mortar or concrete according to an embodiment of the present invention;

[0053] Figure 5 is an actual test picture of one group of Comparative Example 1 of the present invention;

[0054] Figure 6Actual test pictures of one group of Comparative Example 1 of the present invention (not in the same group as Figure 5 ).

[0055] Explanation of reference numerals:

[0056] 1. Bottom mold; 2. Limiting top mold; 3. Metal cylinder; 4. Positioning groove; 5. Positioning block; 6. Handle; 7. Pull ring; 8. Sealing wax; 9. Sponge; 10. Corrosion solution. Detailed implementation manners

[0057] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which the present invention pertains. The test reagents used in the following embodiments are all conventional chemical reagents unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0058] The present invention will be described in detail below with reference to the embodiments and the accompanying drawings.

[0059] A test model for the ion penetration depth of mortar or concrete, comprising a bottom mold 1 and a limiting top mold 2. The upper part of the bottom mold 1 is inclined, and the limiting top mold 2 is installed on the bottom mold 1; a plurality of rows of metal cylinder assemblies 3 are inserted into the limiting top mold 2. The metal cylinder assembly 3 includes a plurality of uniformly distributed metal cylinders 3; the metal cylinder 3 is in the shape of a cylinder obliquely cut along the axis, and the inclination angle of the metal cylinder 3 is the same as the inclination angle of the limiting top mold 2. Positioning grooves 4 are provided at both ends of the bottom mold 1, and positioning blocks 5 matching the positioning grooves 4 are provided at both ends of the limiting top mold 2; handles 6 are provided at both ends of the limiting top mold 2; pull rings 7 are provided above the metal cylinders 3. Sealing wax 8 is provided around the bottom mold 1, and beeswax is applied to the lower end of the inclined end of the bottom mold 1; the lower end of the inclined end of the bottom mold 1 is the thinnest part, and the thinnest part of the upper inclined surface is sealed with sealing wax 8 as required to ensure that the corrosion solution will not penetrate from the upper inclined surface. The number of the metal cylinder assemblies 3 is at least 1.

[0060] A method for using a test model for the ion penetration depth of mortar or concrete, characterized by comprising the following steps:

[0061] S1: Select the size of the test model according to the maximum aggregate size of the mortar to be tested, add water to stir the mortar or concrete to be tested, and after the stirring is completed, inject it into the model, and sequentially install the limiting top mold and the metal cylinder on the bottom mold;

[0062] S2: After molding at a certain temperature and humidity, cure for a period of time, and take out the molded mortar from the bottom mold;

[0063] S3: Seal the wax of the mortar demolded in step S2 to obtain a test piece;

[0064] S4: Place a water-absorbing sponge into the corrosion solution. After the sponge is completely soaked, place the specimen obtained in step S3 on the sponge.

[0065] S5: After soaking in the corrosion solution for a period of time, take the leftmost metal cylinder and conduct tests in sequence to determine the penetration depth.

[0066] The corrosion solution is sulfate or chloride salt, such as NaCl solution, Na2SO4 solution, MgCl2 solution, and in actual production, it is a mixed solution of various substances such as NaCl and MgCl2 in salt field brine.

[0067] In step S1, the size of the test model is selected. When the maximum aggregate size of mortar or concrete is fine sand mortar less than 2.36 mm, it is usually required that the minimum size of the mortar mold or construction part shall not be less than 1.5 times the maximum aggregate size. This invention is divided into two types: fine sand mortar mold and coarse sand mortar mold. The smallest parts in the mold are the inner diameter D of the metal cylinder, the shortest height h, and the horizontal spacing x.

[0068] Among them, the maximum aggregate size of fine sand mortar is less than 2.36 mm. For the convenience of molding, its size is enlarged to: the D of the corresponding mold metal cylinder is 5 mm, h is 5 mm, and x is 10 mm, which can all meet the requirement of ≥1.5 times the maximum aggregate size;

[0069] When the maximum aggregate size is coarse sand mortar greater than 2.36 mm, the maximum aggregate size of coarse sand mortar is greater than 2.36 mm. Design the D of the corresponding mold metal cylinder to be h is x is which can all meet the requirement of ≥1.5 times the maximum aggregate size.

[0070] The wall thickness δ of the metal cylinder is 0.5 mm.

[0071] Both Standard DL / T 5126 - 2001 and JG / T 337 - 2011 require the test accuracy to be 1 mm. Among them, JG / T 337 - 2011 requires that the chloride ion penetration depth ≤7 mm. Design the test depth to be n (n≥7 mm),

[0072] That is, the calculation formula for the slope k of the upper surface of the bottom mold is required to be:

[0073] The calculation formula for the maximum height H1 is: H1 = n + h + k×(D + a),

[0074] a is the horizontal distance at the shortest height from the bottom metal cylinder to the bottom mold; the horizontal distance at the shortest height from the bottom metal cylinder to the bottom mold is the same as the horizontal distance at the longest height from the top metal cylinder to the bottom mold; is the maximum aggregate size of the mortar to be measured;

[0075] The calculation formula for the shortest height H2 of the bottom mold is: H2 = h + 1 - k×a,

[0076] The calculation formula for the length L of the bottom mold is L = (n - 1)×x + 2×a + 2×δ + D.

[0077] The specific design is as follows:

[0078] For the fine sand mortar mold, a = 5mm, k = 0.1, H1 = n + 6mm, H2 = 5.5mm, L = 10n + 6.

[0079] Coarse sand mortar mold

[0080] The curing temperature in step S2 is 20 - 30°C, the humidity is 40 - 70%, and the curing age is 28d.

[0081] The wax sealing method in step S3 includes the following steps:

[0082] A1: The mass ratio of rosin to paraffin wax is 1:2 - 3, and it is heated and melted in a metal tray and mixed evenly;

[0083] A2: Immerse the four sides of the demolded mortar into the mixed liquid obtained in step A1 for 1 - 2mm and keep it for 1 - 5s;

[0084] A3: Immerse the bottom end of the upper inclined surface of the demolded mortar into the mixed liquid obtained in step A1 for 1 - 5mm, keep it for 1 - 5s and then take it out, and the wax sealing is completed.

[0085] In step S4, the corrosion solution is placed in a water tank, and a water-absorbing sponge 9 is put in. Wait until the sponge 9 absorbs the corrosion emulsion to saturation, and the liquid level of the corrosion solution in the water tank is not higher than the upper surface of the sponge 9. Then place the specimen on the sponge 9 so that the bottom surface of the specimen contacts the corrosion solution through the contact surface with the sponge 9. The soaking time in step S5 is at least 28d; the number of metal cylinder 3 components is at least 1; when the number of metal cylinder components is one, the ion penetration depth of the mortar or concrete at one time can be measured; when the number of metal cylinder components is multiple, the ion penetration depth of the mortar or concrete at one time can be measured; the soaking time is in gradient; the ion penetration depth of the mortar or concrete at different times can be measured.

[0086] The test in step S5 includes the following steps: Take out the mortar in the cylinder through the metal pull ring 7, spray 0.1% fluorescent yellow indicator and 0.1N silver nitrate solution on its bottom surface. If white precipitate appears, it has penetrated to this depth. Another point can be taken for continuous testing until no white precipitate appears. The vertical distance from the bottom of the metal cylinder 3 at the last point where white precipitate appears to the lower bottom surface is the penetration depth.

[0087] This device takes out a metal cylinder 3 through the metal pull ring 7 and conducts a color reaction on the bottom surface of the mortar. If white precipitate appears, it has penetrated to this depth. Another point can be taken for continuous testing until no white precipitate appears. The height from the bottom of the metal cylinder 3 at the last point where white precipitate appears to the lower bottom surface is the penetration depth. For chloride ions, the color development is carried out by first spraying 0.1N silver nitrate solution and then spraying 0.1% fluorescent yellow indicator. For SO4 2- , the cross-section can be polished by 1 mm powder for XRD scanning, and whether there are sulfate characteristic spectral lines can be judged through the XRD spectrogram.

[0088] Example 1:

[0089] Single metal cylinder 3 component:

[0090] Mix ratio of mortar to be tested: 250 g of P.O 42.5 cement, 750 g of medium sand (maximum particle size less than 2.36 mm), 0.3 g of cellulose ether with 40000 MPa·s, and 170 g of water added. Stir with a planetary mortar mixer and inject into the mold for molding after stirring.

[0091] Immediately after molding, place the metal cylinder 3 with a pull ring 7 on the inclined plane. The horizontal distance from the metal cylinder at the bottom of the mold to the shortest horizontal distance at the lower end of the bottom mold is 5 mm. The slope k of the upper surface of the bottom mold is 0.1, the maximum height H1 of the bottom mold is 21 mm, the shortest height H2 of the bottom mold is 5.5 mm, and the horizontal length of the bottom mold is L = 156 mm.

[0092] The molded specimen is cured under the conditions of temperature (23 ± 2) °C and relative humidity (55 ± 5)%. After 28 days, the specimen is taken out of the outer mold.

[0093] Seal the side surface of the specimen that has reached the curing period with a mixture of rosin and paraffin, and seal the wax 8 at the lower end of the upper inclined plane. The bottom surface and the upper inclined plane are not sealed with wax 8.

[0094] Corrode with 2.5% NaCl solution. During the experiment, place a water-absorbing sponge 9 in the corrosion solution. After the sponge 9 is completely soaked, place the specimen on the sponge 9 to ensure that the bottom surface of the specimen is always in contact with the corrosion solution.

[0095] After soaking for 14 days, take Figure 2At the leftmost point, the mortar in the metal cylinder 3 is taken out through the metal pull ring 7, and a 0.1% fluorescein yellow indicator and a 0.1N silver nitrate solution are sprayed on its bottom surface, showing a white precipitate. The distance from this point to the bottom surface is 1 mm. Then, continue to take the second point for testing, and still a white precipitate is shown. The distance from this point to the bottom surface is 2 mm, and so on until no white precipitate is shown. When testing the 9th cylinder, no white precipitate is shown anymore. The height of this point from the bottom surface is 9 mm, so the penetration depth is 8 mm.

[0096] Example 2:

[0097] Multiple metal cylinder 3 components:

[0098] Mix ratio of mortar to be tested: 250 g of P.O 42.5 cement, 750 g of medium sand (maximum particle size less than 2.36 mm), 0.3 g of cellulose ether with 40000 MPa·s, and 170 g of water added. Stir with a planetary mortar mixer and inject into the mold for molding after stirring.

[0099] Immediately after molding, arrange the metal cylinder 3 with a pull ring 7 on the inclined plane. The horizontal distance from the metal cylinder at the bottom of the mold to the shortest horizontal distance at the lowest part of the bottom mold is 5 mm. The slope k of the upper surface of the bottom mold is 0.1, the maximum height H1 of the bottom mold is 21 mm, the shortest height H2 of the bottom mold is 5.5 mm, and the length L of the bottom mold is 156 mm.

[0100] The molded specimens are cured under the conditions of temperature (23±2)°C and relative humidity (55±5)%. After 28 d, take the specimens out of the outer mold.

[0101] Seal the side surfaces of the specimens cured until the due date with a mixed solution of rosin and paraffin wax, and seal the wax 8 at the lower end of the upper inclined plane. Do not seal the wax 8 on the bottom surface and the upper inclined plane.

[0102] Corrode with a 2.5% NaCl solution. During the experiment, put a water-absorbing sponge 9 into the corrosion solution. After the sponge 9 is completely soaked, place the specimen on the sponge 9 to ensure that the bottom surface of the specimen is always in contact with the corrosion solution.

[0103] After soaking for 14 d, take Figure 3 At the leftmost point, the mortar in the cylinder is taken out through the metal pull ring 7, and a 0.1% fluorescein yellow indicator and a 0.1N silver nitrate solution are sprayed on its bottom surface, showing a white precipitate. The distance from this point to the bottom surface is 1 mm. Then, continue to take the second point for testing, and still a white precipitate is shown. The distance from this point to the bottom surface is 2 mm, and so on until no white precipitate is shown. When testing the 9th cylinder, no white precipitate is shown anymore. The height of this point from the bottom surface is 9 mm, so the penetration depth is 8 mm.

[0104] After soaking for 16 d, take Figure 3At the leftmost point of the other row, the mortar in the cylinder is taken out through the metal pull ring 7, and a 0.1% fluorescent yellow indicator and 0.1N silver nitrate solution are sprayed on its bottom surface, showing a white precipitate. The distance from this point to the bottom surface is 1 mm. Continue to take the second point for testing, and still a white precipitate is shown. The distance from this point to the bottom surface is 2 mm, and so on until no white precipitate is shown. When testing the 10th metal cylinder 3, no white precipitate is shown anymore. The height of this point from the bottom surface is 10 mm, so the penetration depth is 9 mm.

[0105] Comparative Example 1:

[0106] Conventional test method for chloride ion penetration depth:

[0107] Color development method: Reference standard: DL / T 5126-2001 Test procedures for polymer modified cement mortar Test method:

[0108] 1. Molding and curing of specimens: Prepare specimens according to "Mixing method of mortar" in Section 5.1 and "Molding and curing method of mortar specimens" in Section 6.1 of this specification. Three specimens are taken as a group.

[0109] 2. Three days before the end of curing, coat the casting surface and bottom surface of the specimens with a mixture of rosin and paraffin for sealing, and then immerse the specimens in a 2.5% sodium chloride solution at (20±2)°C. The amount of sodium chloride solution should be preferably 5 cm higher than the upper surface of the specimens, and keep the liquid level unchanged. The distance between specimens and from specimens to the bottom of the tank should be kept about 10 mm.

[0110] 3. After the specimens are immersed in the sodium chloride solution for 28 d, take them out, split the specimens into two halves in the middle of the surface coated with the mixture of rosin and paraffin, brush off the remaining powder on the fracture surface, and spray a 0.1% fluorescent yellow indicator and 0.1N silver nitrate solution on it. The area showing fluorescence is the chloride ion penetration area. Take three equally divided points at the junction of the fluorescent area and the non-discolored area, measure the distance from them to the two non-waxed side surfaces, accurate to 1 mm, and the average value of the six points is used as the chloride ion penetration depth value (L.) of one specimen, as shown in the figure.

[0111] The fracture surface is uneven, and due to the existence of aggregates in the test blocks, the boundary of the chloride ion penetration area after color development is not obvious, the error of penetration depth test is large, the specimens can only be tested for one penetration age, and cannot be reused for continuous testing of different penetration ages. Actual test pictures are as Figure 6 and Figure 5 shown.

[0112] Comparative Example 2:

[0113] Except for the coated surface and its opposite surface, the other four surfaces of the specimens are sealed with solvent-free epoxy paint. If there are pinholes in the epoxy coating, they should be sealed.

[0114] a) Apply coating to 3 test specimens. At the same time, prepare 3 blank test specimens without applying the permeable coating.

[0115] b) After the test specimens are dried in an oven at 50 °C for 48 h, take them out and cool them to room temperature in an environment with a temperature of (20 ± 2) °C and a relative humidity of (60 ± 5)%. Place a glass rod with a diameter of 10 mm at the bottom of a flat-bottomed container, place the coated surface of the test specimen face down on the glass rod, and pour in a NaCl solution with a temperature of (20 ± 2) °C and a concentration of 35%. The liquid level should be 1 - 2 mm higher than the coated surface of the test specimen; take out the specimen after 24 h and dry it in an oven at 50 °C for 24 h.

[0116] d) Grind the concrete block into powder layer by layer at a unit of 1 mm from the coated surface and collect it. Place the powder sample in an oven at (105 ± 5) °C for 2 h, take it out, put it in a desiccator to cool to room temperature, weigh 5 - 20 g of the sample with an analytical balance with a precision of 0.001 g and pour it into a conical flask; conduct the test according to the method for measuring the chloride ion content in the powder.

[0117] e) Repeat the above operations for the powder ground at each 1 mm depth. A distribution curve with the depth as the abscissa and the chloride ion content as the ordinate can be obtained. Then, the chloride ion penetration depth is based on the turning point between the descending stage and the final flat stage of the content distribution curve, accurate to 1 mm.

[0118] f) The arithmetic mean of the measured values of the 3 test specimens is used as the chloride ion penetration depth of this group of test specimens.

[0119] Difficulties in testing:

[0120] ① In step d, grinding into powder layer by layer at a unit of 1 mm requires high-precision operating instruments. The high grinding precision makes the test difficult and has a high risk factor; ② In actual testing, the powder ground out cannot be completely cleaned, which will cause interlayer contamination and low test accuracy; ③ The operation is carried out layer by layer, with a large workload, and the test specimen can only be tested for one penetration age period and cannot be reused for continuous testing of different penetration age periods.

[0121] The above is only a preferred embodiment of the present invention, and it is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A test model for the ion penetration depth of mortar or concrete, characterized in that: It includes a bottom mold and a limiting top mold. The upper part of the bottom mold is inclined, and the limiting top mold is installed on the bottom mold. A number of rows of metal cylinder assemblies are inserted into the limiting top mold. The metal cylinder assembly includes a number of evenly distributed metal cylinders. The metal cylinder is in the shape of a cylinder obliquely cut with the axis, and the inclination angle of the oblique section of the metal cylinder is the same as that of the limiting top mold.

2. The ion penetration depth test model for mortar or concrete according to claim 1, wherein: Positioning grooves are provided at both ends of the bottom mold, and positioning blocks matching the positioning grooves are provided at both ends of the limiting top mold; handles are provided at both ends of the limiting top mold. Pulling rings are provided above the metal cylinders.

3. A model for testing the ion penetration depth of mortar or concrete according to claim 1, characterized in that: The number of the metal cylinder assemblies is at least 1.

4. A method for using a test model for the ion penetration depth of mortar or concrete according to any one of claims 1 to 3, characterized in that: It includes the following steps: S1: Select the size of the test model according to the maximum aggregate size of the mortar to be tested. Add water to stir the mortar or concrete to be tested, and after stirring is completed, inject it into the model. Install the limiting top mold and the metal cylinders on the bottom mold in sequence. S2: After forming under certain temperature and humidity conditions, cure for a period of time, and take out the formed mortar from the bottom mold. S3: Wax the mortar after demolding in step S2 to obtain a specimen. S4: Put a piece of absorbent sponge into the corrosion solution. After the sponge is completely soaked, place the specimen obtained in step S3 on the sponge. S5: After soaking in the corrosion solution for a period of time, take the leftmost metal cylinder and conduct tests in sequence to judge the penetration depth.

5. The usage method of a test model for the ion penetration depth of mortar or concrete according to claim 4, characterized in that: In the step S1, the size of the test model is selected. When the maximum aggregate size of mortar or concrete is fine sand mortar less than 2.36 mm, when the designed test depth is n, the inner diameter D of the metal cylinder of the corresponding mold is 5 mm, the shortest height h of the metal cylinder is 5 mm, the horizontal spacing x of the cylinders is 10 mm, the horizontal distance a from the bottom metal cylinder to the shortest height of the bottom mold is 5 mm, the slope ratio k is 0.1, the maximum height H1 of the bottom mold is (n + 6) mm, the shortest height H2 of the bottom mold is 5.5 mm, and the total length L of the mold is (10n + 6) mm; When the maximum aggregate size is greater than 2.36 mm for coarse sand mortar, when the designed test depth is n, the inner diameter D of the metal cylinder is The shortest height h of the metal cylinder is The horizontal spacing x of the cylinders is The horizontal distance a from the bottom metal cylinder to the shortest height of the bottom die is The slope ratio k of the slope is The maximum height H1 of the bottom die is The shortest height H2 of the bottom die is The total length L of the mold is The wall thickness δ of the metal cylinder is 0.5 mm.

6. According to the method for using a test model for testing the ion penetration depth of mortar or concrete according to claim 4, it is characterized in that: The calculation formula for the slope k of the upper surface of the bottom mold is: The calculation formula for the maximum height H1 of the bottom mold is: H1 = n + h + k×(D + a). The calculation formula for the shortest height H2 of the bottom mold is: H2 = h + 1 - k×a. The calculation formula for the length L of the bottom mold is L = (n - 1)×x + 2×a + 2×δ + D. is the maximum aggregate size of the mortar to be tested, in mm; a is the horizontal distance from the bottommost metal cylinder to the shortest height of the bottom mold; the horizontal distance from the bottommost metal cylinder to the shortest height of the bottom mold is the same as the horizontal distance from the topmost metal cylinder to the longest height of the bottom mold, and the unit is mm. δ is the wall thickness of the metal cylinder, and the unit is mm. D is the inner diameter of the metal cylinder, and the unit is mm. n is the designed test depth, and the unit is mm.

7. A method for using a test model for the ion penetration depth of mortar or concrete, according to claim 4, characterized in that: The curing temperature in step S2 is 20 - 30 °C, the humidity is 40 - 70%, and the curing age is 28 d.

8. A method for using a test model for the ion penetration depth of mortar or concrete, according to claim 4, characterized in that: The waxing method in step S3 includes the following steps: A1: The mass ratio of rosin to paraffin is 1:2 - 3, and heat and melt them evenly in a metal tray. A2: Immerse the four sides of the demolded mortar into the mixed liquid obtained in step A1 by 1 - 2 mm and keep it for 1 - 5 s. A3: Immerse the bottom end of the upper inclined plane of the demolded mortar into the mixed liquid obtained in step A1 by 1 - 5 mm, keep it for 1 - 5 s and then take it out, and the waxing is completed.

9. A method for using a test model for the ion penetration depth of mortar or concrete, according to claim 4, characterized in that: The number of the metal cylinder assemblies is at least 1. When the number of the metal cylinder assemblies is one, the ion penetration depth of the mortar or concrete at one time can be measured. When the number of the metal cylinder assemblies is multiple, the ion penetration depths of the mortar or concrete at multiple times can be measured; the soaking time is in gradient; the ion penetration depths of the mortar or concrete at different times can be measured.

10. A method for using a test model for the ion penetration depth of mortar or concrete, according to claim 4, characterized in that: The test in the step S5 includes the following steps: take out the mortar in the cylinder through the metal pull ring, spray 0.1% fluorescein yellow indicator and 0.1N silver nitrate solution on its bottom surface. If white precipitate appears, it has penetrated to this depth. Then, the second point can be taken for continuous testing until no white precipitate appears. The vertical distance from the bottom of the metal cylinder at the last point where white precipitate appears to the lower bottom surface is the penetration depth.

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