Anti-corrosion admixture for sprayed concrete as well as preparation method and application of anti-corrosion admixture

Abstract

The invention belongs to the technical field of building materials, and particularly discloses an anti-corrosion admixture for sprayed concrete and a preparation method of the anti-corrosion admixture. The anti-corrosion admixture is obtained by modifying the dense component and the adsorption component, then compounding with the hydrophobic component and the surface active component and uniformly dispersing in water. And moreover, the dense component and the adsorption component are taken from various domestic wastes, so that the cost of an anti-corrosion technology is reduced, the wastes are recycled, and the method is green and environment-friendly. The anti-corrosion admixture can be applied to sprayed concrete, calcium ions can be treated through physical adsorption and chemical precipitation, the hydrophobicity and compactness of the concrete can be enhanced, the problem of sprayed concrete corrosion is solved from inside to outside, the anti-corrosion performance of the sprayed concrete is remarkably improved, and the sprayed concrete is stable for a long time.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials. Specifically, it relates to an anti-corrosion additive for shotcrete, its preparation method, and its application in shotcrete. Background Art

[0002] Shotcrete is often used for pouring thin-walled structures such as tunnel linings, walls, ceilings, etc., or linings of other structures and protective layers for steel structures. Therefore, the concrete structure is exposed to environmental water for a long time, and there is an ion concentration difference between the concrete pore solution and the environmental water, resulting in the continuous diffusion and loss of calcium ions, etc. into the environmental water, and causing the dissolution of C-S-H gel, the decrease of concrete alkalinity, and the decline of material properties, resulting in corrosion. It can be said that corrosion is one of the main diseases of shotcrete.

[0003] In existing research reports on improving the anti-corrosion performance of shotcrete, it is mainly improved by enhancing the compactness and hydrophobicity of the concrete structure to reduce the internal water transmission rate of the concrete; that is, by restricting the transmission of environmental water inside the concrete to improve the anti-corrosion performance of shotcrete. To enhance the compactness, it is mainly by adding admixtures or active filling materials to shotcrete to reduce the porosity, but the effect is limited. And the hydrophobic modification of concrete is mainly divided into surface hydrophobicity and overall hydrophobicity; the surface hydrophobicity of concrete will be affected by factors such as cracking and spalling, and the amount of hydrophobic agent required for overall hydrophobicity is large, the cost is high, and it often causes a significant decrease in the strength of concrete.

[0004] Currently, there are many studies on concrete anti-corrosion technology, but there are certain problems in all of them. For example, an anti-corrosion additive for tunnel lining concrete is composed of a waterproof component, a waterproof auxiliary, a calcium-fixing component, a calcium-fixing auxiliary, and water. However, the way of fixing calcium ions in this technology is mainly chemical combination, the action mechanism is single, the aging time is short, and the cost is high. Another example is a waterproof material, cement, and concrete. The waterproof material involved therein needs to introduce nano-silica with a high cost, and the main action mechanism is to increase the compactness and hydrophobicity of the concrete, and it fails to treat the calcium ions dissolved from the hydration products, and the long-term stability of its waterproof material has not been verified.

[0005] In addition to the above research on reducing the porosity by internal admixture, there are also reports on achieving hydrophobic effects by external brushing. For example, an anti-calcium corrosion cement-based material for concrete, its preparation method, and application mainly include cement, mineral powder, silica fume, fine aggregate, aluminum sulfate, sodium silicate, urea, and a water reducer. Brushing on the concrete surface can reduce the calcium ion dissolution amount, but the effect of applying this cement-based material on the surface of shotcrete has not been verified, and it is easily affected by the surface humidity, spalling, and cracking of the concrete.

[0006] In summary, in view of the current research status of the anti-corrosion technology of shotcrete, it is urgent to study an anti-corrosion technology of shotcrete with low cost, environmental friendliness, good effect and strong long-term stability. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the present invention provides an anti-corrosion admixture for shotcrete with low cost, environmental friendliness, good effect and strong long-term stability. The anti-corrosion admixture is prepared by compounding multiple components and modifying some of the components, so that each component plays multiple roles, thereby significantly improving the anti-corrosion performance of the shotcrete applied with it.

[0008] In order to achieve the above-mentioned invention purpose, the present invention adopts the following technical scheme:

[0009] An anti-corrosion admixture for shotcrete, comprising the following components mixed evenly by mass percentage:

[0010]

[0011] Specifically, the modified dense component is obtained by treating the dense component with an alkali solution to remove the surface hydrophobic impurities and then drying it.

[0012] In the above modification method, after the dense component is treated with an alkali solution, the hydrophobic impurities on the particle surface are reacted and dissolved, so that the adhesion with the cement paste can be improved when it is applied to shotcrete.

[0013] Furthermore, the dense component can be at least one of arthropod exoskeleton powder, glass powder, and rubber powder.

[0014] The above alkali solution can be any conventional alkali solution, preferably non-calcium alkali solutions such as sodium hydroxide and potassium hydroxide.

[0015] The above-mentioned modified dense component, on the one hand, enhances the compactness of the concrete through physical filling, which can improve the mechanical properties of the concrete; on the other hand, after being modified, its adhesion strength with the concrete also increases, thereby significantly improving the anti-medium penetration and calcium dissolution performance of the concrete. Among them, after the glass powder is modified, the silicate and meta-aluminate formed on the surface can also react with calcium ions in the concrete pore solution to form calcium silicate and calcium meta-aluminate with lower solubility, further improving the anti-corrosion performance of the concrete.

[0016] Specifically, the modified adsorption component is obtained by treating the adsorption component with an alkali solution to remove the surface hydrophobic impurities, then adsorbing the calcium precipitation solution, and then drying it.

[0017] In the above modification method, first, after the adsorption component is treated with an alkali solution, the hydrophobic impurities on the particle surface are dissolved by the reaction, so that the physical adsorption effect on calcium ions can be enhanced when applied to shotcrete; second, the adsorption component treated with the alkali solution is immersed in a calcium precipitation solution to first adsorb a calcium precipitant, further ensuring the precipitation of calcium ions when applied to shotcrete. Thus, it is ensured that the modified adsorption component has the dual effects of physical adsorption and chemical binding.

[0018] Furthermore, the adsorption component can be at least one of eggshell powder, cinder powder, and coffee residue powder.

[0019] The above alkali solution can be any conventional alkali solution, as long as it can dissolve and remove the hydrophobic impurities on the surface of the adsorption component.

[0020] Furthermore, the calcium precipitation solution can be a solution that is easy to precipitate calcium ions, such as an oxalate solution, a carbonate solution, a bicarbonate solution, a phosphate solution, etc., and is not particularly limited here.

[0021] For the above modified adsorption component, each substance before modification has a porous structure and a large specific surface area, and can effectively solidify the dissolved calcium ions by physical adsorption. Moreover, after being modified, it has the dual effects of physical adsorption and chemical binding, significantly improving the ability to solidify calcium ions, thereby enhancing the anti-corrosion performance of shotcrete.

[0022] Specifically, the hydrophobic component is selected from at least one of silanes, siloxanes, long-chain fatty acids, and methyl silanolates.

[0023] When this anti-corrosion admixture is applied to shotcrete, silanes, siloxanes, and long-chain fatty acids can form a hydrophobic adsorption layer on the surface of cement particles, refine the pore structure of the hardened paste, improve the compactness and hydrophobicity of the concrete, and make the concrete have good impermeability; while methyl silanolate generates methyl silanol under the action of water and carbon dioxide, and methyl silanol further condenses and undergoes a chemical reaction with the hydration products to form a network-like organosilicon resin film with a waterproof effect inside the concrete, thereby enhancing the impermeability and durability of the concrete.

[0024] Preferably, the hydrophobic component can be at least one of cetyltrimethoxysilane, hexamethyldisiloxane, palmitic acid, docosahexaenoic acid, and sodium methyl silanolate.

[0025] Specifically, the surface active component is selected from at least one of cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, sodium methylene bisnaphthalenesulfonate, and sodium dodecyl sulfate.

[0026] On the one hand, the surface active component can optimize the adsorption of the adsorption component to the calcium precipitation solution, and on the other hand, it can also improve the dispersibility between solid particles in the anti-corrosion additive.

[0027] The present invention also provides a preparation method of the above anti-corrosion additive for shotcrete, comprising the following steps:

[0028] Modification of the dense component: The dense component is treated with an alkali solution and then dried to obtain a modified dense component;

[0029] Modification of the adsorption component: The adsorption component is treated with an alkali solution, impregnated in a calcium precipitation solution for adsorption, and then dried to obtain a modified adsorption component;

[0030] Obtaining the anti-corrosion additive: The modified dense component, the modified adsorption component, the hydrophobic component, and the surface active component are uniformly dispersed in water to obtain a suspension, which is the product.

[0031] Preferably, the hydrophobic component and the surface active component can be first dispersed uniformly in a part of water at a slightly elevated temperature (generally 50°C to 60°C is sufficient) to obtain a first dispersion. Then, the modified dense component and the modified adsorption component are dispersed uniformly in the remaining part of the water to obtain a second dispersion. Finally, the first dispersion and the second dispersion are mixed uniformly. The above step-by-step mixing method is more likely to obtain a uniformly dispersed anti-corrosion additive.

[0032] Another object of the present invention is also to provide the application of the above anti-corrosion additive. It can be added to shotcrete by equally mass substituting the mixing water according to a dosage of 5% to 10% of the dosage of the cementitious material.

[0033] The present invention modifies the dense component and the adsorption component, and then compound them with the hydrophobic component and the surface active component and uniformly disperse them in water to obtain the anti-corrosion additive. After being applied to shotcrete, it can not only treat calcium ions through multiple processes of physical adsorption and chemical precipitation, but also enhance the hydrophobicity and density of the concrete, solving the corrosion problem of shotcrete from both the "inside" and "outside" directions, significantly improving the anti-corrosion performance of shotcrete, and maintaining long-term stability. Moreover, the dense component and the adsorption component are taken from various domestic wastes, which not only reduces the cost of the anti-corrosion technology, but also realizes the recycling of waste, being green and environmentally friendly. Specific embodiments

[0034] The components of the anti-corrosion additive provided by the present invention will be described below through specific examples. However, those skilled in the art will understand that the following examples are only specific examples of the anti-corrosion additive of the present invention and are not used to limit all of them. On the contrary, these examples are provided to explain the principles of the present invention and its practical applications, so that other technicians in the art can understand various embodiments of the present invention and various modifications suitable for specific intended applications.

[0035] The following Table 1 shows the compositions of the anti-corrosion additives provided in Examples 1 to 10, based on the mass percentage of each component in the anti-corrosion additive.

[0036] Table 1 Compositions of the anti-corrosion additives in Examples 1 to 10

[0037]

[0038] Specifically, the above anti-corrosion additives are prepared by the following method.

[0039] Example 1

[0040] First, soak the shrimp shell and crab shell powder in a 10 wt% sodium hydroxide solution for about 6 h. The hydrophobic impurities on the surface of the shrimp shell and crab shell powder are removed. After draining and passing through a 140 μm sieve, modified shrimp shell and crab shell powder is obtained.

[0041] Then, soak the eggshell powder in a 10 wt% sodium hydroxide solution for about 6 h. The hydrophobic impurities on the surface of the eggshell powder are removed. After drying, grinding and passing through a 140 μm sieve, it is then added to a saturated sodium oxalate solution and left standing for 24 h and then drained to obtain modified eggshell powder.

[0042] In the third step, mix cetyltrimethoxysilane, cetyltrimethylammonium bromide with half of the water, and heat in a water bath for about 0.5 h, controlling the heating temperature at 50 °C to make a mixed solution A.

[0043] In the fourth step, mix the modified shrimp shell and crab shell powder and the modified eggshell powder with the other half of the water, stir at a speed of about 2000 r / min for 0.5 h to mix evenly and make a mixed solution B.

[0044] Finally, mix the mixed solution A and the mixed solution B and disperse them fully to make the anti-corrosion additive.

[0045] Example 2

[0046] First, soak the glass powder in a 10 wt% sodium hydroxide solution for about 6 h. The hydrophobic impurities on the surface of the glass powder are removed. After draining and passing through a 140 μm sieve, modified glass powder is obtained.

[0047] Then, the coal slag powder was soaked in 10wt% sodium hydroxide solution for about 6 hours to remove hydrophobic impurities on the surface of the coal slag powder. After drying and grinding, it was passed through a 140μm sieve and then added to a saturated sodium oxalate solution and allowed to stand for 24 hours before draining to obtain modified coal slag powder.

[0048] The third step is to mix hexamethyldisiloxane, sodium dodecylbenzene sulfonate and half of the water, and heat in a water bath for about 0.5 h, controlling the heating temperature to 60° C. to prepare a mixed solution A.

[0049] In the fourth step, the modified glass powder and the modified coal slag powder are mixed with the other half of the water, stirred at a speed of about 2000 r / min for 0.5 h, and mixed evenly to form a mixed solution B.

[0050] Finally, the mixed solution A and the mixed solution B are mixed and fully dispersed to prepare an anti-corrosion admixture.

[0051] Example 3

[0052] First, the waste rubber powder is washed and soaked in a 10 wt % sodium hydroxide solution for about 6 hours, and the hydrophobic impurities on the surface of the waste rubber powder are removed. After being drained and sieved through a 140 μm sieve, the modified rubber powder is obtained.

[0053] Then, the coffee grounds were soaked in a 10 wt % sodium hydroxide solution for about 6 hours to remove hydrophobic impurities on the surface of the coffee grounds. After drying and grinding, the grounds were sieved with a 140 μm sieve and then added to a saturated potassium oxalate solution and allowed to stand for 24 hours before being drained to obtain modified coffee grounds.

[0054] The third step is to mix stearic acid, sodium methylene dinaphthalene sulfonate and half of the water, and heat in a water bath for about 0.5 h, controlling the heating temperature to 60° C. to prepare a mixed solution A.

[0055] In the fourth step, the modified rubber powder and the modified coffee grounds powder are mixed with the other half of the water, stirred at a speed of about 2000 r / min for 0.5 h, and mixed evenly to prepare a mixed solution B.

[0056] Finally, the mixed solution A and the mixed solution B are mixed and fully dispersed to prepare an anti-corrosion admixture.

[0057] Example 4

[0058] First, the waste glass powder is washed and soaked in a 10 wt % sodium hydroxide solution for about 6 hours, and the hydrophobic impurities on the surface of the waste glass powder are removed. After being drained and sieved with a 140 μm sieve, modified glass powder is obtained.

[0059] Then, soak the eggshell powder in a 10 wt% sodium hydroxide solution for about 6 h. The hydrophobic impurities on the surface of the eggshell powder are removed. After drying and grinding, it is sieved through a 140-μm sieve, and then added to a saturated sodium oxalate solution and left standing for 24 h before draining to obtain the modified eggshell powder.

[0060] In the third step, mix palmitic acid, sodium dodecylbenzenesulfonate with half of the water, and heat in a water bath for about 0.5 h, controlling the heating temperature at 60 °C to make the mixed solution A.

[0061] In the fourth step, mix the modified glass powder and the modified eggshell powder with the other half of the water, and stir at a speed of about 2000 r / min for 0.5 h to mix evenly and make the mixed solution B.

[0062] Finally, mix the mixed solution A and the mixed solution B and disperse them fully to make the anti-corrosion additive.

[0063] Example 5

[0064] First, clean and soak the waste glass powder in a 10 wt% sodium hydroxide solution for about 6 h. The hydrophobic impurities on the surface of the waste glass powder are removed. After draining and sieving through a 140-μm sieve, the modified glass powder is obtained.

[0065] Then, soak the coffee residue powder in a 10 wt% sodium hydroxide solution for about 6 h. The hydrophobic impurities on the surface of the coffee residue powder are removed. After drying and grinding, it is sieved through a 140-μm sieve, and then added to a saturated sodium oxalate solution and left standing for 24 h before draining to obtain the modified coffee residue powder.

[0066] In the third step, mix palmitic acid, sodium dodecylbenzenesulfonate with half of the water, and heat in a water bath for about 0.5 h, controlling the heating temperature at 60 °C to make the mixed solution A.

[0067] In the fourth step, mix the modified glass powder and the modified coffee residue powder with the other half of the water, and stir at a speed of about 2000 r / min for 0.5 h to mix evenly and make the mixed solution B.

[0068] Finally, mix the mixed solution A and the mixed solution B and disperse them fully to make the anti-corrosion additive.

[0069] Example 6

[0070] First, clean and soak the waste glass powder in a 10 wt% sodium hydroxide solution for about 6 h. The hydrophobic impurities on the surface of the waste glass powder are removed. After draining and sieving through a 140-μm sieve, the modified glass powder is obtained.

[0071] Then, the coal slag powder was soaked in 10wt% sodium hydroxide solution for about 6 hours to remove hydrophobic impurities on the surface of the coal slag powder. After drying and grinding, it was passed through a 140μm sieve and then added to a saturated potassium oxalate solution and allowed to stand for 24 hours before draining to obtain modified coal slag powder.

[0072] In the third step, sodium methylsiliconate, hexadecyltrimethylammonium bromide and half of the water are mixed, and heated in a water bath for about 0.5 h, with the heating temperature controlled at 60° C. to prepare a mixed solution A.

[0073] In the fourth step, the modified glass powder and the modified coal slag powder are mixed with the other half of the water, stirred at a speed of about 2000 r / min for 0.5 h, and mixed evenly to form a mixed solution B.

[0074] Finally, the mixed solution A and the mixed solution B are mixed and fully dispersed to prepare an anti-corrosion admixture.

[0075] Example 7

[0076] Firstly, the waste glass powder is washed and soaked in a saturated calcium hydroxide solution for about 6 hours, and the hydrophobic impurities on the surface of the waste glass powder are removed. After being drained and sieved with a 140 μm sieve, the modified glass powder is obtained.

[0077] Then, the eggshell powder was soaked in a saturated calcium hydroxide solution for about 6 hours to remove hydrophobic impurities on the surface of the eggshell powder. After drying and grinding, it was passed through a 140 μm sieve and then added to a saturated potassium oxalate solution and allowed to stand for 24 hours before draining to obtain modified eggshell powder.

[0078] In the third step, hexadecyltrimethoxysilane, sodium dodecylbenzenesulfonate and half of the water are mixed, and heated in a water bath for about 0.5 h, with the heating temperature controlled at 60° C. to prepare a mixed solution A.

[0079] In the fourth step, the modified glass powder and the modified eggshell powder are mixed with the other half of the water, stirred at a speed of about 2000 r / min for 0.5 h, and mixed evenly to form a mixed solution B.

[0080] Finally, the mixed solution A and the mixed solution B are mixed and fully dispersed to prepare an anti-corrosion admixture.

[0081] Example 8

[0082] Firstly, the shrimp shell and crab shell powder were cleaned and soaked in a saturated calcium hydroxide solution for about 6 hours, and the hydrophobic impurities on the surface of the shrimp shell and crab shell powder were removed. After being drained and passed through a 140 μm sieve, the modified shrimp shell and crab shell powder were obtained.

[0083] Then, the coffee grounds were soaked in a saturated calcium hydroxide solution for about 6 hours to remove hydrophobic impurities on the surface of the coffee grounds. After drying and grinding, the grounds were sieved with a 140 μm sieve and then added to a saturated sodium carbonate solution and allowed to stand for 24 hours before being drained to obtain modified coffee grounds.

[0084] The third step is to mix stearic acid, hexadecyltrimethylammonium bromide and half of the water, and heat in a water bath for about 0.5 h, controlling the heating temperature to 60° C. to prepare a mixed solution A.

[0085] In the fourth step, the modified shrimp shell and crab shell powder and the modified coffee grounds powder are mixed with the other half of the water, stirred at a speed of about 2000 r / min for 0.5 h, and mixed evenly to prepare a mixed solution B.

[0086] Finally, the mixed solution A and the mixed solution B are mixed and fully dispersed to prepare an anti-corrosion admixture.

[0087] Example 9

[0088] First, the waste rubber powder was washed and soaked in a 10 wt % potassium hydroxide solution for about 6 hours, and the hydrophobic impurities on the surface of the waste rubber powder were removed. After being drained and sieved through a 140 μm sieve, modified rubber powder was obtained.

[0089] Then, the eggshell powder was soaked in a 10wt% potassium hydroxide solution for about 6 hours to remove hydrophobic impurities on the surface of the eggshell powder. After drying and grinding, it was passed through a 140μm sieve and then added to a saturated sodium bicarbonate solution and allowed to stand for 24 hours before draining to obtain modified eggshell powder.

[0090] In the third step, hexadecyltrimethoxysilane, hexadecyltrimethylammonium bromide and half of the water are mixed, and heated in a water bath for about 0.5 h, with the heating temperature controlled at 60° C. to prepare a mixed solution A.

[0091] In the fourth step, the modified rubber powder and the modified eggshell powder are mixed with the other half of the water, stirred at a speed of about 2000 r / min for 0.5 h, and mixed evenly to form a mixed solution B.

[0092] Finally, the mixed solution A and the mixed solution B are mixed and fully dispersed to prepare an anti-corrosion admixture.

[0093] Example 10

[0094] Firstly, the waste shrimp shell and crab shell powder are cleaned and soaked in 10wt% potassium hydroxide solution for about 6 hours, and the hydrophobic impurities on the surface of the waste shrimp shell and crab shell powder are removed. After being drained and sieved through a 140μm sieve, the modified shrimp shell and crab shell powder are obtained.

[0095] Then, the coffee grounds were soaked in a 10 wt % potassium hydroxide solution for about 6 hours to remove hydrophobic impurities on the surface of the coffee grounds. After drying and grinding, the grounds were sieved with a 140 μm sieve and then added to a saturated sodium phosphate solution and allowed to stand for 24 hours before being drained to obtain modified coffee grounds.

[0096] In the third step, hexamethyldisiloxane, hexadecyltrimethylammonium bromide and half of the water are mixed, and heated in a water bath for about 0.5 h, with the heating temperature controlled at 60° C. to prepare a mixed solution A.

[0097] In the fourth step, the modified shrimp shell and crab shell powder and the modified coffee grounds powder are mixed with the other half of the water, stirred at a speed of about 2000 r / min for 0.5 h, and mixed evenly to prepare a mixed solution B.

[0098] Finally, the mixed solution A and the mixed solution B are mixed and fully dispersed to prepare an anti-corrosion admixture.

[0099] In order to verify the necessity of the components in the above-mentioned anti-corrosion admixture of the present invention and the modification method thereof, the following comparative experiments were carried out.

[0100] Comparative Example 1

[0101] The similarities between this comparative example and Example 2 are not described here, and only the differences from Example 2 are described. The difference between this comparative example and Example 2 is that when the adsorption component coal slag powder is modified, only alkali solution is used for soaking, and it is not soaked in calcium precipitation solution after soaking, and the comparative modified coal slag powder is obtained; the rest is referred to Example 2 to obtain the comparative anti-corrosion admixture.

[0102] Comparative Example 2

[0103] The similarities between this comparative example and Example 2 are not described here, and only the differences from Example 2 are described. The difference between this comparative example and Example 2 is that: no hydrophobic component is used; the rest is as described in Example 2 to obtain a comparative anti-corrosion admixture.

[0104] Comparative Example 3

[0105] The similarities between this comparative example and Example 2 are not described here, and only the differences from Example 2 are described. The difference between this comparative example and Example 2 is that: no modified densifying component is used; the rest is as described in Example 2 to obtain a comparative anti-corrosion admixture.

[0106] Comparative Example 4

[0107] The similarities between this comparative example and Example 2 will not be elaborated here, and only the differences from Example 2 will be described. The difference between this comparative example and Example 2 is that: the adsorbent component, coal cinder powder, was directly immersed in the calcium precipitation solution without being soaked in the alkali solution, and the corresponding comparative modified coal cinder powder was obtained; the rest was referred to as described in Example 2 to obtain the comparative anti-corrosion additive.

[0108] Comparative Example 5

[0109] The similarities between this comparative example and Example 2 will not be elaborated here, and only the differences from Example 2 will be described. The difference between this comparative example and Example 2 is that: the dense component, glass powder, was not soaked in the alkali solution; the rest was referred to as described in Example 2 to obtain the comparative anti-corrosion additive.

[0110] Comparative Example 6

[0111] The similarities between this comparative example and Example 2 will not be elaborated here, and only the differences from Example 2 will be described. The difference between this comparative example and Example 2 is that: the mass ratio of the hydrophobic component is 5%, the mass ratio of the modified dense component is 5%, and the mass ratio of the modified adsorbent component is 5%; the rest was referred to as described in Example 2 to obtain the comparative anti-corrosion additive.

[0112] Comparative Example 7

[0113] The similarities between this comparative example and Example 2 will not be elaborated here, and only the differences from Example 2 will be described. The difference between this comparative example and Example 2 is that: the mass ratio of the hydrophobic component is 40%; the rest was referred to as described in Example 2 to obtain the comparative anti-corrosion additive.

[0114] Comparative Example 8

[0115] The similarities between this comparative example and Example 2 will not be elaborated here, and only the differences from Example 2 will be described. The difference between this comparative example and Example 2 is that: the mass ratio of the modified dense component is 40%; the rest was referred to as described in Example 2 to obtain the comparative anti-corrosion additive.

[0116] Comparative Example 9

[0117] The similarities between this comparative example and Example 2 will not be elaborated here, and only the differences from Example 2 will be described. The difference between this comparative example and Example 2 is that: the mass ratio of the modified adsorbent component is 40%; the rest was referred to as described in Example 2 to obtain the comparative anti-corrosion additive.

[0118] Comparative Example 10

[0119] The similarities between this comparative example and Example 2 will not be elaborated here, and only the differences from Example 2 will be described. The difference between this comparative example and Example 2 lies in that the mass proportion of the surface active component is 2%; the rest refers to that described in Example 2, and a comparative anti-corrosion additive is obtained.

[0120] The above anti-corrosion additive of the present invention can be incorporated into shotcrete for utilization. Generally, it can be incorporated into shotcrete at an incorporation amount of 5% - 10% of the amount of cementitious materials. Since the anti-corrosion additive is a liquid additive, when incorporated into shotcrete, the same mass of mixing water needs to be deducted.

[0121] The following Application Examples 1 - 10 respectively correspond to the above Examples 1 - 10, and shotcrete is provided.

[0122] The specific composition of each shotcrete is as follows:

[0123] The cement used is P·O 42.5 cement produced by Anhui Conch Co., Ltd., and the dosage is 500 kg / m 3 . The fine aggregate is river sand with a fineness modulus of 2.6, and the dosage is 840 kg / m 3 ; the coarse aggregate is basalt with a particle size of 5.0 mm - 10.0 mm, and the dosage is 800 kg / m 3 . The accelerating agent is an alkali-free accelerating agent, and the dosage is 25 kg / m 3 . The water-reducing agent is a polycarboxylate water-reducing agent with a solid content of 11%, and the dosage is 1.5% of the amount of cement. The water dosage is 185 kg / m 3 . The dosage of the anti-corrosion additive is 5% of the amount of cement, and it equivalently replaces the mixing water.

[0124] In order to test the anti-corrosion performance of the above shotcrete, it is first cured.

[0125] Specifically, after the concrete is mixed, cube specimens with dimensions of 100 mm × 100 mm × 100 mm are formed, cured with the mold at room temperature for 1 d, then demolded, and cured under standard conditions until 28 d.

[0126] Then comes the anti-corrosion performance test.

[0127] Specifically, to ensure the one-dimensional transport law of calcium ions, the four sides of each shotcrete specimen were coated with epoxy resin before the test. After the epoxy resin cured, the shotcrete specimens were immersed in a 6 mol / L ammonium chloride solution. After immersion to the specified ages (14 d, 28 d, 56 d), the compressive strength and standard-cured strength of the shotcrete specimens were tested respectively, and the strength loss rate Δσ of the specimens was calculated using Equation (1). The test procedure referred to "Standard Test Method for Physical and Mechanical Properties of Concrete" (GB / T 50081-2019). Meanwhile, the calcium ion content in the immersion solution was tested, and the calcium dissolution rate Γ of the specimens was calculated using Equation (2). Finally, to ensure the stability of the ammonium chloride solution components, the solution was replaced every 14 days.

[0128]

[0129] Where: σ 溶蚀 is the compressive strength of the shotcrete after erosion at different ages, and σ 标养 is the compressive strength of the specimen after standard curing for the same time.

[0130]

[0131] Where: C t is the calcium ion content in the immersion solution after erosion at different ages, and C0 is the total initial calcium ion amount inside the shotcrete specimen.

[0132] Meanwhile, according to the above method, the comparative anti-corrosion additives provided in each of the above comparative examples were also applied to the shotcrete respectively to obtain comparative shotcrete, designated as Application Comparative Example 1 to Application Comparative Example 10.

[0133] The anti-corrosion performance parameters of the shotcrete provided in each of the above Application Examples 1 to 10 and the comparative shotcrete provided in each of the Application Comparative Examples 1 to 10 are shown in Table 2 below. Table 2 Anti-corrosion performance parameters of the shotcrete provided in Application Examples 1 - 10 and Application Comparative Examples 1 - 10

[0134]

[0135]

[0136] As can be seen from the corrosion resistance test results of the shotcrete in Table 2, compared with the blank group, the corrosion resistance technology corresponding to each application example significantly improved the corrosion resistance of the shotcrete. Among them, the effect of Application Example 2 is the best. After soaking in 6mol / L ammonium chloride solution for 56 days, the strength loss rate of the specimen is only 5.1%, and the calcium dissolution rate is 3.1%. After 56 days of corrosion of the shotcrete provided by the other application examples, the strength loss is not more than 15.6%, and the calcium dissolution rate is not more than 9.3%, which is much lower than that of the blank group. This shows that the anti-corrosion effect of the invention technology is significant and the action time is long.

[0137] Comparing Application Example 1 and Application Example 4, it can be found that when the dense component in the anti-corrosion admixture is glass powder, even with less dosage, it shows less strength loss and less calcium dissolution in the corresponding shotcrete, indicating that using glass powder as the dense component has better effects. This is because after the glass powder is modified, silicate and meta-aluminate formed on the surface can also react with calcium ions in the concrete pore solution to form calcium silicate and calcium meta-aluminate with lower solubility, thereby further improving the corrosion resistance of the concrete.

[0138] At the same time, comparing Application Example 3 and Application Example 5 also shows that using glass powder as the dense component has better corrosion resistance of the concrete.

[0139] Comparing Application Example 7 with Application Example 1, it is found that when the alkaline solution in which the dense component in the anti-corrosion admixture is soaked changes from sodium hydroxide to calcium hydroxide, it shows higher strength loss and higher calcium dissolution rate in the corresponding shotcrete. This shows that calcium silicate and calcium meta-aluminate formed on the surface of the glass powder after being treated with saturated calcium hydroxide solution no longer have the effect of adsorbing calcium ions, and only play the role of denseness and anti-medium penetration performance of the dense component.

[0140] Compared with Application Example 2, the strength loss rate and calcium dissolution rate of the comparative shotcrete specimens provided by Application Comparative Examples 1 to 3 are higher. Specifically, on the basis of Application Example 2, the anti-corrosion admixture in Application Comparative Example 1 did not use oxalate to treat the coal cinder powder, so this modified coal cinder powder has no ability to chemically combine calcium ions and can only physically adsorb calcium ions. This shows that the modification method of the adsorption component plays a key role in the anti-corrosion effect of the anti-corrosion admixture. In addition, Application Comparative Example 2 and Application Comparative Example 3 removed the hydrophobic component hexamethyldisiloxane and the dense component modified glass powder respectively on the basis of Application Example 2, and both showed performance deterioration; thus, it can be seen that the anti-corrosion effect of using the dense component and the adsorption component in compound, or the hydrophobic component and the adsorption component in compound is lower than that of the three-component compounding method. There is a synergistic enhancement effect between the hydrophobic component, the dense component and the adsorption component, which can significantly improve the corrosion resistance of the shotcrete.

[0141] Compared with Application Example 2, the strength loss rate and calcium dissolution rate of the comparative shotcrete specimens provided by Application Comparative Example 4 and Application Comparative Example 5 are both higher.

[0142] Specifically, on the basis of Application Example 2, in Application Comparative Example 4, the slag powder was not treated with an alkali solution. As a result, the hydrophobic impurities on the surface of the modified slag powder were not removed, and the adsorption rate of the slag powder to the calcium precipitation solution decreased, resulting in a weakened ability of the modified slag powder to chemically solidify calcium ions. In addition, in Application Comparative Example 5, the glass powder was not treated with an alkali solution. Therefore, the hydrophobic impurities on the surface of the unmodified glass powder led to a decrease in the bonding strength with the cement paste, resulting in an increased strength loss and an increased calcium dissolution rate of the corresponding shotcrete.

[0143] Compared with Application Example 2, the strength loss rate and calcium dissolution rate of the comparative shotcrete provided by Application Comparative Example 6 to Application Comparative Example 10 are both higher.

[0144] Specifically, on the basis of Application Example 2, in Application Comparative Example 6, the contents of the hydrophobic component, modified dense component, and modified adsorption component in the anti-corrosion additive are all 5%, which is lower than the aforementioned defined range. This shows that when the components in the anti-corrosion additive are lower than the defined range, the anti-corrosion effect of the anti-corrosion additive is significantly weakened.

[0145] On the basis of Application Example 2, the content of the hydrophobic component in the corresponding anti-corrosion additive of Application Comparative Example 7 is 40%, exceeding the defined range; this indicates that too much hydrophobic component in the anti-corrosion additive will reduce the anti-corrosion performance of the corresponding shotcrete.

[0146] On the basis of Application Example 2, the content of the modified dense component in Application Comparative Example 8 is 40%, exceeding the defined range; this is mainly because too much modified dense component in the anti-corrosion additive will exacerbate its agglomeration, resulting in a reduced effect of the modified dense component in refining the pore structure of the concrete.

[0147] On the basis of Application Example 2, the content of the modified adsorption component in Application Comparative Example 9 is 40%, exceeding the defined range; this is mainly because too much modified adsorption component in the anti-corrosion additive will cause agglomeration, thereby reducing the effect of the modified adsorption component in adsorbing calcium ions in the concrete.

[0148] On the basis of Application Example 2, the surface active component of the corresponding anti-corrosion additive in Application Comparative Example 10 is 2%, exceeding the defined range; this is mainly because adding an anti-corrosion additive containing an excessive amount of surface active component during the mixing process of the shotcrete will introduce a large number of air bubbles in the concrete mixture, and a large number of pores will appear inside the hardened shotcrete, thereby exacerbating the calcium dissolution of the shotcrete specimens under corrosion conditions.

[0149] While the invention has been shown and described with reference to particular embodiments, those skilled in the art will understand that various changes in form and detail may be made herein without departing from the spirit and scope of the invention as defined by the claims and their equivalents.

Claims

1. An anti-corrosion additive for shotcrete, characterized in that, Comprising the following components uniformly mixed by mass percentage: Among them, the modified dense component is obtained by treating the dense component with a first alkaline solution to remove surface hydrophobic impurities and then drying; The modified adsorption component is obtained by first treating the adsorption component with a second alkaline solution to remove surface hydrophobic impurities, then adsorbing a calcium precipitation solution, and then drying.

2. The anti-corrosion additive according to claim 1, characterized in that, The dense component is selected from at least one of arthropod exoskeleton powder, glass powder, and rubber powder.

3. The anti-corrosion additive according to claim 2, wherein The first alkaline solution is a non-calcium alkaline solution.

4. The anti-corrosion additive according to any one of claims 1 to 3, characterized in that The adsorption component is selected from at least one of eggshell powder, cinder powder, and coffee residue powder.

5. The anti-corrosion additive according to claim 4, characterized in that, The calcium precipitation solution is selected from any one of oxalate solution, carbonate solution, bicarbonate solution, and phosphate solution.

6. The anti-corrosion additive according to claim 4, characterized in that, The hydrophobic component is selected from at least one of silanes, siloxanes, long-chain fatty acids, and methyl silicate.

7. The anti-corrosion additive according to claim 6, characterized in that, The hydrophobic component is selected from at least one of cetyltrimethoxysilane, hexamethyldisiloxane, palmitic acid, docosahexaenoic acid, and sodium methyl silanolate.

8. The anti-corrosion additive according to claim 4, wherein The surface active component is selected from at least one of cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, sodium methylene bisnaphthalenesulfonate, and sodium dodecyl sulfate.

9. The preparation method of the anti-corrosion additive according to any one of claims 1 to 8, characterized in that, Including: Modification step of the dense component: Treat the dense component with a first alkaline solution and then dry to obtain the modified dense component; Modification step of the adsorption component: Treat the adsorption component with a second alkaline solution, immerse it in a calcium precipitation solution for adsorption, and then dry to obtain the modified adsorption component; Obtaining step of the anti-corrosion additive: Uniformly disperse the modified dense component, the modified adsorption component, the hydrophobic component, and the surface active component in water to obtain a suspension, that is, obtained.

10. The application of the anti-corrosion additive according to any one of claims 1 to 8, characterized in that, Mix the anti-corrosion additive into the shotcrete at a dosage of 5% - 10% of the amount of the binder in the shotcrete and replace the mixing water in the shotcrete with an equal mass, that's all.

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