A method for evaluating the performance of anti-icing coating on concrete of water delivery channels

Abstract

The present invention discloses a method for evaluating the performance of an anti-icing coating on concrete of a water conveyance channel. The present invention evaluates the performance of an anti-icing coating on concrete of a water conveyance channel through deicing efficiency and coating durability, wherein the deicing efficiency of the coating is reflected by the pull-out strength between the coating and ice, an ice pull-out strength test is performed using an "8"-shaped specimen to measure the ice pull-out strength, and a cyclic test is performed to reflect the coating durability. The anti-icing coating performance evaluation method of the present invention can fully reflect the performance of the anti-icing coating on concrete of a water conveyance channel, and provide a basis for solving the problem of water conveyance in the water conveyance channel during the ice period in winter, ensuring safe operation during the ice period, and improving the water supply capacity during the ice period.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic concrete, and in particular to a method for evaluating the performance of an anti-icing coating on concrete of a water conveyance channel. Background Art

[0002] Northeast, Northwest and North my country are in seasonal frozen ground areas, and frost damage to buildings is very common, especially channel concrete. At present, researchers have conducted in-depth research on the problem of frost heave damage to channels and have achieved a lot of research results. This problem has also been well solved. For some areas prone to ice disasters, the anti-icing technology of concrete has attracted widespread attention from researchers around the world. There are four main types of anti-icing measures in anti-icing technology: solution anti-icing, mechanical deicing, thermal anti-icing and coating anti-icing. Among them, anti-icing coatings mainly achieve the purpose of anti-icing through the special surface properties and microphase morphology of the material. This type of material needs to have both anti-icing and ice-repelling properties, and reduce or even eliminate ice and snow accumulation by extending the freezing time and reducing the adhesion of ice. There are three main reasons for delaying the ice condensation time: 1. The surface of the anti-icing coating is generally a hydrophobic surface, and the contact area between the surface water droplets and the substrate is very small, which can inhibit the formation of ice with fewer nucleation sites; 2. According to the classical thermodynamic nucleation theory, the nucleation free energy barrier ΔG required for ice nucleation formation and growth is positively correlated with the static water contact angle, that is, the larger the contact angle, the higher the ΔG required for nucleation, and the more difficult it is for water droplets to nucleate; 3. The micro-nano rough structure on the coating surface forms an air layer between the substrate and the water droplets, which has a heat insulation effect to a certain extent and reduces heat transfer, reducing the freezing rate of water droplets. The anti-icing coating can reduce the adhesion strength of ice mainly because the super-hydrophobic surface has excellent waterproof properties, so that water does not penetrate into the concrete, but only condenses on the surface, resulting in less adhesion between the ice layer and the concrete. In principle, coating anti-icing should be said to be an ideal anti-icing method, because it belongs to active protection, low energy consumption, environmental friendliness and a wide range of applications.

[0003] In actual application, the performance of anti-icing coating directly determines the winter anti-icing effect of water channels. However, the current research is more about concrete anti-icing coating technology, and there are fewer methods for testing and evaluating the performance of anti-icing coatings on water channel concrete. This is because the complexity of the interaction between ice and coating makes it difficult to establish a universal standard. The combination and destruction of the ice-coating interface depends on the characteristic parameters of the interface, the shape of the specimen, and the way the load is applied. The surface coating modification of water channel concrete realizes passive anti-icing of the main channel material. The current performance evaluation of anti-icing coatings is based on the laboratory characterization of hydrophobic surfaces, that is, measuring the contact angle of the coating. A few will conduct icing tests on the coating, which is not targeted enough for the main body of the water channel and cannot fully reflect the coating's improvement in the deicing efficiency of the channel concrete. Summary of the invention

[0004] In view of the above background technology, in order to solve the problems of water delivery and long-term use of water conveyance channels during the ice period in winter, ensure safe operation during the ice period, and improve the water supply capacity and long-term applicability during the ice period, the present invention designs a performance evaluation method for anti-icing coating of concrete for water conveyance channels, which fully reflects the performance of anti-icing coating of channel concrete. Specifically, the performance of anti-icing coating is mainly evaluated based on deicing efficiency and anti-icing durability of coating.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A method for evaluating the performance of an anti-icing coating on a water channel concrete comprises:

[0007] (1) Preparation of test specimens: a group of "8"-shaped concrete specimens were formed, and after curing the "8"-shaped concrete specimens for 14 days, the specimens were cut along the transverse center line to obtain two groups of half "8"-shaped specimens. The cut cross-sections were then cleaned and coated with anti-icing coatings. After the coating was cured, half "8"-shaped concrete specimens were obtained. The half "8"-shaped concrete specimens were placed in an "8"-shaped test mold that matched the specimens, and the other half was filled with tap water to conduct an icing test, that is, the molds were removed after curing for 10 hours at the typical temperature of the winter ice period in the water transfer channel, and two groups of "8"-shaped concrete specimens to be tested were obtained;

[0008] (2) Ice pull-out strength test of concrete test pieces: Use a tensile testing machine to test the bonding strength of the two groups of "8"-shaped concrete test pieces after demolding in step (1). At the same time, a group without anti-icing coating is set up for comparison. The maximum and minimum values ​​in the test piece group are removed, and the average value of the remaining values ​​is taken as the pull-out strength between the anti-icing coating and ice;

[0009] (3) Icing-deicing cycle test: Take a group of "8"-shaped concrete test pieces in step (2) and repeat the ice pull-out strength test in step (2). Record the pull-out strength of each test. After 25 cycles of testing, draw an ice pull-out strength development curve to reflect the attenuation of the anti-icing coating.

[0010] The cyclic test in step (3) specifically comprises preparing a concrete test piece through the icing test in step (1), then testing the ice pull-out strength of the anti-icing coating of the test piece through the ice pull-out strength test in step (2), and finally placing the test piece after the pull-out strength test at room temperature for natural ice melting and de-icing. After de-icing is completed, the icing test in step (1) is repeated again to prepare the test piece. The icing test preparation of the test piece - ice pull-out strength test - ice melting and de-icing is one test cycle. The icing cycle test simulates the icing and de-icing process through the icing-ice pull-out test to study the influence of this process on the coating performance and evaluate the coating durability.

[0011] (4) Evaluation of anti-icing coating performance: The de-icing efficiency of the coating is reflected by the pull-out strength between the anti-icing coating and ice in step (2). The lower the pull-out strength, the higher the de-icing efficiency of the coating. The durability of the anti-icing coating is reflected by the attenuation of the anti-icing coating in step (3).

[0012] Furthermore, the number of concrete specimens in a group in step (1) of the present invention is at least 4.

[0013] Furthermore, the cross section of the semi-figure-8 test piece in step (1) of the present invention needs to be cut open and cleaned with acetone for degreasing, and a coarse sandpaper brush is used to remove particles and powder and then dried.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] At present, the method of evaluating the anti-icing performance of the coating by measuring the contact angle is inaccurate. When the coating reaches the hydrophobic level (contact angle>90°), the anti-icing performance of the coating is not simply positively correlated with the contact angle. The evaluation method of the present invention determines the deicing efficiency and durability of the coating through experiments to evaluate the performance of the anti-icing coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The development of ice binding force of anti-icing coating during icing cycle. DETAILED DESCRIPTION

[0017] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form.

[0018] Example

[0019] A method for evaluating the performance of an anti-icing coating on a water channel concrete comprises:

[0020] (1) Preparation of test specimens: a group of "8"-shaped concrete specimens were formed, and after curing the "8"-shaped concrete specimens for 14 days, the specimens were cut along the transverse center line to obtain two groups of half "8"-shaped specimens. The cut cross-sections were then cleaned and coated with anti-icing coatings. After the coating was cured, half "8"-shaped concrete specimens were obtained. The half "8"-shaped concrete specimens were placed in an "8"-shaped test mold that matched the specimens, and the other half was filled with tap water to conduct an icing test, that is, the molds were removed after curing for 10 hours at the typical temperature of the winter ice period in the water transfer channel, and two groups of "8"-shaped concrete specimens to be tested were obtained;

[0021] (2) Ice pull-out strength test of concrete test pieces: Use a tensile testing machine to test the bonding strength of the two groups of "8"-shaped concrete test pieces after demolding in step (1). At the same time, a group without anti-icing coating is set up for comparison. The maximum and minimum values ​​in the test piece group are removed, and the average value of the remaining values ​​is taken as the pull-out strength between the anti-icing coating and ice;

[0022] (3) Icing-deicing cycle test: Take a group of "8"-shaped concrete test pieces in step (2) and repeat the ice pull-out strength test in step (2). Record the pull-out strength of each test. After 25 cycles of testing, draw an ice pull-out strength development curve to reflect the attenuation of the anti-icing coating.

[0023] The cyclic test in step (3) specifically comprises preparing a concrete test piece through the icing test in step (1), then testing the ice pull-out strength of the anti-icing coating of the test piece through the ice pull-out strength test in step (2), and finally placing the test piece after the pull-out strength test at room temperature for natural ice melting and de-icing. After de-icing is completed, the icing test preparation of the test piece in step (1) is repeated again. The icing test preparation of the test piece - ice pull-out strength test - ice melting and de-icing constitutes one test cycle.

[0024] (4) Evaluation of anti-icing coating performance: The de-icing efficiency of the coating is reflected by the pull-out strength between the anti-icing coating and ice in step (2). The lower the pull-out strength, the higher the de-icing efficiency of the coating. The durability of the anti-icing coating is reflected by the attenuation of the anti-icing coating in step (3).

[0025] Furthermore, the number of concrete specimens in a group in step (1) of the present invention is at least 4.

[0026] Furthermore, the cross section of the semi-figure-8 test piece in step (1) of the present invention needs to be cut open and cleaned with acetone for degreasing, and a coarse sandpaper brush is used to remove particles and powder and then dried.

[0027] The ice pull-out strength test results of the anti-icing coating on concrete specimens are shown in Table 1, the results of the comparison of coating contact angle and deicing efficiency parameters are shown in Table 2, and the results of the coating icing / deicing cycle test are shown in Table 3 and Figure 1 shown.

[0028] Table 1 Ice pull-out strength test results of different anti-icing coatings and blank group

[0029]

[0030]

[0031] Table 2 Comparison of coating contact angle, icing difficulty and deicing efficiency parameters

[0032] Material Contact angle / ° Ice pull-out strength / kPa Control group 20.75 976.20 PU 84.04 504.26 PFS 140.01 236.58 PTFE 86.43 880.18

[0033] Table 3 Coating icing / deicing cycle test

[0034]

[0035]

[0036] From the test results in Tables 1 and 2, it can be seen that the contact angle and deicing efficiency are not a simple linear relationship. The performance of the anti-icing coating of the water channel concrete needs to be evaluated through targeted tests, especially the ice pull-out strength can fully reflect the performance of the anti-icing coating of the water channel concrete; Tables 3 and Figure 1 The change in ice pull-out strength of the anti-icing coating during the icing / de-icing cycle test can reflect the stability and durability of the coating during service. The coating stability and durability are important indicators in engineering practice, and they are measured and evaluated through ice pull-out strength test cycles.

Claims

1. A method for evaluating the performance of anti-icing coating on water channel concrete, characterized in that: include: (1) Preparation of test specimens: a group of "8"-shaped concrete specimens were formed, and after curing the "8"-shaped concrete specimens for 14 days, the specimens were cut along the transverse center line to obtain two groups of half "8"-shaped specimens. The cut cross-sections were then cleaned and coated with anti-icing coatings. After the coating was cured, half "8"-shaped concrete specimens were obtained. The half "8"-shaped concrete specimens were placed in an "8"-shaped test mold that matched the specimens, and the other half was filled with tap water to conduct an icing test, that is, after curing for 10 hours at the typical temperature of the winter ice period in the water transfer channel, the molds were removed to obtain two groups of "8"-shaped concrete specimens to be tested; (2) Ice pull-out strength test of concrete test pieces: Use a tensile testing machine to test the bonding strength of the two groups of "8"-shaped concrete test pieces after demolding in step (1). At the same time, a group without anti-icing coating is set up for comparison. The maximum and minimum values ​​in the test piece group are removed, and the average value of the remaining values ​​is taken as the pull-out strength between the anti-icing coating and ice; (3) Icing-deicing cycle test: Take a group of "8"-shaped concrete test pieces in step (2) and repeat the ice pull-out strength test in step (2). Record the pull-out strength of each test. After 25 cycles of testing, draw an ice pull-out strength development curve to reflect the attenuation of the anti-icing coating. The cyclic test in step (3) specifically comprises preparing a concrete test piece through the icing test in step (1), then testing the ice pull-out strength of the anti-icing coating of the test piece through the ice pull-out strength test in step (2), and finally placing the test piece after the pull-out strength test at room temperature for natural ice melting and de-icing. After de-icing is completed, the icing test preparation of the test piece in step (1) is repeated again. The icing test preparation of the test piece - ice pull-out strength test - ice melting and de-icing constitutes one test cycle. (4) Evaluation of anti-icing coating performance: The de-icing efficiency of the coating is reflected by the pull-out strength between the anti-icing coating and ice in step (2). The lower the pull-out strength, the higher the de-icing efficiency of the coating. The durability of the anti-icing coating is reflected by the attenuation of the anti-icing coating in step (3).

2. A method for evaluating the performance of an anti-icing coating on a water channel concrete according to claim 1, characterized in that: The number of concrete specimens in a group described in step (1) is at least 4.

3. The method for evaluating the performance of an anti-icing coating on a water channel concrete according to claim 1, characterized in that: The cross section of the semi-8-shaped specimen in step (1) is cut open and cleaned by using acetone to remove grease, and a coarse sandpaper brush is used to remove particles and powder and the specimen is dried.

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